Question: In this experiment, which were part of an experimental group?

Choices:
- the unpruned tomato plants
- the pruned tomato plants

The passage below describes an experiment.

Lester worked in a restaurant that had a vegetable garden. Part of his job was to care for the tomato plants. He had heard that pruning, or trimming, tomato plants can help tomatoes grow. He wondered if pruning would affect how well his tomato plants grew.
Lester chose 24 tomato plants that were similar in size. He pruned an equal number of branches from each of the first 12 plants. He left the other 12 plants unpruned. Then, each week, Lester weighed the tomatoes that he picked from each group of plants.
Figure: a tomato plant.

natural science

Identify control and experimental groups

Experiments have variables, or parts that change. You can design an experiment to investigate whether changing a variable between different groups has a specific outcome.
For example, imagine you want to find out whether adding fertilizer to soil affects the height of pea plants. You could investigate this question with the following experiment:
You grow one group of pea plants in soil with fertilizer and measure the height of the plants. This group shows you what happens when fertilizer is added to soil. Since fertilizer is the variable whose effect you are investigating, this group is an experimental group.
You grow another group of pea plants in soil without fertilizer and measure the height of the plants. Since this group shows you what happens when fertilizer is not added to the soil, it is a control group.
By comparing the results from the experimental group to the results from the control group, you can conclude whether adding fertilizer to the soil affects pea plant height.

Solution:
In this experiment, Lester investigated whether pruning tomato plants affects the weight of the tomatoes. So, the pruned tomato plants were part of an experimental group.
The unpruned tomato plants were not pruned. So, they were not part of an experimental group.


Question: Which of these states is farthest north?

Choices:
- Delaware
- West Virginia
- Iowa
- Alabama

social science

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west.
A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction.
The north arrow points to the North Pole. On most maps, north is at the top of the map.

Solution: To find the answer, look at the compass rose. Look at which way the north arrow is pointing. Iowa is farthest north.


Question: Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

Choices:
- The magnetic force is weaker in Pair 2.
- The strength of the magnetic force is the same in both pairs.
- The magnetic force is weaker in Pair 1.

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

natural science

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart.
These pulls and pushes between magnets are called magnetic forces. The stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.

Solution:
Distance affects the strength of the magnetic force. But the distance between the magnets in Pair 1 and in Pair 2 is the same.
So, the strength of the magnetic force is the same in both pairs.


Question: What is the capital of North Dakota?

Choices:
- Kansas City
- Bismarck
- Fargo
- Davenport

social science

Solution: Bismarck is the capital of North Dakota.


Question: Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

Choices:
- The strength of the magnetic force is the same in both pairs.
- The magnetic force is weaker in Pair 1.
- The magnetic force is weaker in Pair 2.

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

natural science

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart.
These pulls and pushes between magnets are called magnetic forces. The stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.


Question: Which country is highlighted?

Choices:
- Tonga
- New Zealand
- Tuvalu
- Kiribati

social science

Identify and select countries of Oceania

Solution: This country is Tonga.


Question: What is the capital of Mississippi?

Choices:
- Charleston
- Portland
- Jackson
- Biloxi

social science

Identify state capitals of the Southeast

Solution: Jackson is the capital of Mississippi.


Question: Does Chelonoidis nigra have cells that have a nucleus?

Choices:
- no
- yes

This organism is Chelonoidis nigra. It is a member of the animal kingdom.
Chelonoidis nigra is commonly called a Galápagos giant tortoise. These large tortoises live on the Galápagos Islands. When Spanish sailors arrived at these islands in the 1530s, about 200,000 Galápagos giant tortoises lived on the islands. The Spanish sailors named the islands after a Spanish word for tortoise, galápago.

natural science

Describe, classify, and compare kingdoms

In the past, scientists classified living organisms into two groups: plants and animals. Over the past 300 years, scientists have discovered many more types of organisms. Today, many scientists classify organisms into six broad groups, called kingdoms.
Organisms in each kingdom have specific traits. The table below shows some traits used to describe each kingdom.
 | Bacteria | Archaea | Protists | Fungi | Animals | Plants
How many cells do they have? | one | one | one or many | one or many | many | many
Do their cells have a nucleus? | no | no | yes | yes | yes | yes
Can their cells make food? | some species can | some species can | some species can | no | no | yes

Solution: Chelonoidis nigra is an animal. Animal cells have a nucleus.


Question: What is the direction of this push?

Choices:
- toward the boy's thumb
- away from the boy's thumb

A boy plays with marbles. He pushes one of the marbles with his thumb.

natural science

One object can make another object move with a push or a pull.
The direction of a push is away from the object that is pushing.
The direction of a pull is toward the object that is pulling.

Solution: The boy pushes his marble away from his thumb. The direction of the push is away from the boy's thumb.


Question: What is the name of the colony shown?

Choices:
- Massachusetts
- Ohio
- Indiana
- New Hampshire

social science

Solution:
The colony is Massachusetts.
The Massachusetts Colony included land that would later become the state of Maine. Maine was never its own colony.


Question: Is hematite a mineral or a rock?

Choices:
- rock
- mineral

Hematite has the following properties:
metallic luster
not made by living things
fixed crystal structure
found in nature
solid
pure substance

natural science

Minerals are the building blocks of rocks. A rock can be made of one or more minerals.
Minerals and rocks have the following properties:
Property | Mineral | Rock
It is a solid. | Yes | Yes
It is formed in nature. | Yes | Yes
It is not made by organisms. | Yes | Yes
It is a pure substance. | Yes | No
It has a fixed crystal structure. | Yes | No
You can use these properties to tell whether a substance is a mineral, a rock, or neither.
Look closely at the last three properties:
Minerals and rocks are not made by organisms.
Organisms make their own body parts. For example, snails and clams make their shells. Because they are made by organisms, body parts cannot be  minerals or rocks.
Humans are organisms too. So, substances that humans make by hand or in factories are not minerals or rocks.
A mineral is a pure substance, but a rock is not.
A pure substance is made of only one type of matter.  Minerals are pure substances, but rocks are not. Instead, all rocks are mixtures.
A mineral has a fixed crystal structure, but a rock does not.
The crystal structure of a substance tells you how the atoms or molecules in the substance are arranged. Different types of minerals have different crystal structures, but all minerals have a fixed crystal structure. This means that the atoms and molecules in different pieces of the same type of mineral are always arranged the same way.
However, rocks do not have a fixed crystal structure. So, the arrangement of atoms or molecules in different pieces of the same type of rock may be different!

Solution: Hematite has all the properties of a mineral. So, hematite is a mineral.


Question: What is the expected ratio of offspring with mutated antennae to offspring with normal antennae? Choose the most likely ratio.

Choices:
- 1:3
- 0:4
- 3:1
- 2:2
- 4:0

This passage describes the antenna type trait in fruit flies:
Most fruit flies have a pair of antennae on their head. But, some flies appear to have an extra pair of legs on their head instead! These flies have a mutation, or change, in a gene that affects body development. This mutation makes the cells in the fly's head form mutated antennae that are like legs.
In a group of fruit flies, some individuals have mutated antennae and others have normal antennae. In this group, the gene for the antenna type trait has two alleles. The allele for mutated antennae (A) is dominant over the allele for normal antennae (a).
This Punnett square shows a cross between two fruit flies.

natural science

Use Punnett squares to calculate ratios of offspring types

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
A Punnett square shows what types of offspring a cross can produce. The expected ratio of offspring types compares how often the cross produces each type of offspring, on average. To write this ratio, count the number of boxes in the Punnett square representing each type.
For example, consider the Punnett square below.
 | F | f
F | FF | Ff
f | Ff | ff
There is 1 box with the genotype FF and 2 boxes with the genotype Ff. So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.

Solution:
To determine how many boxes in the Punnett square represent offspring with mutated antennae or normal antennae, consider whether each phenotype is the dominant or recessive allele's version of the antenna type trait. The question tells you that the A allele, which is for mutated antennae, is dominant over the a allele, which is for normal antennae.
Mutated antennae is the dominant allele's version of the antenna type trait. A fruit fly with the dominant version of the antenna type trait must have at least one dominant allele for the antenna type gene. So, offspring with mutated antennae must have the genotype AA or Aa.
There are 3 boxes in the Punnett square with the genotype AA or Aa. These boxes are highlighted below.
Normal antennae is the recessive allele's version of the antenna type trait. A fruit fly with the recessive version of the antenna type trait must have only recessive alleles for the antenna type gene. So, offspring with normal antennae must have the genotype aa.
There is 1 box in the Punnett square with the genotype aa. This box is highlighted below.
So, the expected ratio of offspring with mutated antennae to offspring with normal antennae is 3:1. This means that, on average, this cross will produce 3 offspring with mutated antennae for every 1 offspring with normal antennae.


Question: Which statement describes the Mount Rainier National Park ecosystem?

Choices:
- It has many evergreen trees.
- It has soil that is frozen year-round.

Figure: Mount Rainier National Park.
Mount Rainier National Park is a taiga ecosystem in Washington State. The park is named after a volcano called Mount Rainier, which is covered in glaciers.

natural science

An environment includes all of the biotic, or living, and abiotic, or nonliving, things in an area. An ecosystem is created by the relationships that form among the biotic and abiotic parts of an environment.
There are many different types of terrestrial, or land-based, ecosystems. Here are some ways in which terrestrial ecosystems can differ from each other:
the pattern of weather, or climate
the type of soil
the organisms that live there

Solution: A taiga is a type of ecosystem. Taigas have the following features: long, cold winters and short, cool summers, many evergreen trees, and soil that is poor in nutrients. So, the following statements describe the Mount Rainier National Park ecosystem: long, cold winters and short, cool summers, many evergreen trees, and soil that is poor in nutrients. It has soil that is poor in nutrients. It has many evergreen trees. The following statement does not describe Mount Rainier National Park: long, cold winters and short, cool summers, many evergreen trees, and soil that is poor in nutrients. It has soil that is frozen year-round.


Question: Does this passage describe the weather or the climate?

Choices:
- climate
- weather

Figure: Houston.
Houston is a city near the coast of Texas. A record 42 inches of rain fell near Houston during the last week of July in 1979.
Hint: Weather is what the atmosphere is like at a certain place and time. Climate is the pattern of weather in a certain place.

natural science

The atmosphere is the layer of air that surrounds Earth. Both weather and climate tell you about the atmosphere.
Weather is what the atmosphere is like at a certain place and time. Weather can change quickly. For example, the temperature outside your house might get higher throughout the day.
Climate is the pattern of weather in a certain place. For example, summer temperatures in New York are usually higher than winter temperatures.

Solution:
Read the passage carefully.
Houston is a city near the coast of Texas. A record 42 inches of rain fell near Houston during the last week of July in 1979.
The underlined part of the passage tells you about the amount of rain that fell during a single week in 1979. This passage describes the atmosphere at a certain place and time. So, this passage describes the weather.


Question: Look at the models of molecules below. Select the elementary substance.

Choices:
- bromine
- hydrazine
- trichlorofluoromethane

natural science

Identify elementary substances and compounds using models

There are more than 100 different chemical elements, or types of atoms. Chemical elements make up all of the substances around you.
A substance may be composed of one chemical element or multiple chemical elements. Substances that are composed of only one chemical element are elementary substances. Substances that are composed of multiple chemical elements bonded together are compounds.
Every chemical element is represented by its own atomic symbol. An atomic symbol may consist of one capital letter, or it may consist of a capital letter followed by a lowercase letter. For example, the atomic symbol for the chemical element boron is B, and the atomic symbol for the chemical element chlorine is Cl.
Scientists use different types of models to represent substances whose atoms are bonded in different ways. One type of model is a ball-and-stick model. The ball-and-stick model below represents a molecule of the compound boron trichloride.
In a ball-and-stick model, the balls represent atoms, and the sticks represent bonds. Notice that the balls in the model above are not all the same color. Each color represents a different chemical element. The legend shows the color and the atomic symbol for each chemical element in the substance.


Question: Compare the average kinetic energies of the particles in each sample. Which sample has the higher temperature?

Choices:
- neither; the samples have the same temperature
- sample A
- sample B

The diagrams below show two pure samples of gas in identical closed, rigid containers. Each colored ball represents one gas particle. Both samples have the same number of particles.

natural science

Identify how particle motion affects temperature and pressure

The temperature of a substance depends on the average kinetic energy of the particles in the substance. The higher the average kinetic energy of the particles, the higher the temperature of the substance.
The kinetic energy of a particle is determined by its mass and speed. For a pure substance, the greater the mass of each particle in the substance and the higher the average speed of the particles, the higher their average kinetic energy.

Solution:
Each particle in sample B has more mass than each particle in sample A. The particles in sample B also have a higher average speed than the particles in sample A. So, the particles in sample B have a higher average kinetic energy than the particles in sample A.
Because the particles in sample B have the higher average kinetic energy, sample B must have the higher temperature.


Question: What is the capital of South Dakota?

Choices:
- Springfield
- Pierre
- Rapid City
- Frankfort

social science

Solution: Pierre is the capital of South Dakota.


Question: Which animal's legs are also adapted for wading?

Choices:
- African sacred ibis
- kookaburra

Shoebills live near marshes and lakes in Africa. They eat fish, frogs, and small reptiles that live in shallow water. Shoebills hunt their prey by walking through water, or wading.
The 's legs are adapted for wading. They are lightweight and keep the bird's body above the water.
Figure: shoebill.

natural science

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors.
Arms, legs, flippers, and wings are different types of limbs. The type of limbs an animal has is an example of an adaptation. Animals' limbs can be adapted in different ways. For example, long legs might help an animal run fast. Flippers might help an animal swim. Wings might help an animal fly.

Solution:
Look at the picture of the shoebill.
Long legs help the shoebill keep its body above the surface of the water while wading. Thin legs are easier to move through the water.
Now look at each animal. Figure out which animal has a similar adaptation.
The African sacred ibis has long, thin legs. Its legs are adapted for wading.
The kookaburra has short legs. Its legs are not adapted for wading. The kookaburra uses its legs to walk and perch.


Question: Which solution has a higher concentration of pink particles?

Choices:
- neither; their concentrations are the same
- Solution A
- Solution B

The diagram below is a model of two solutions. Each pink ball represents one particle of solute.

natural science

A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent.
The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent.
concentration = particles of solute / volume of solvent

Solution:
In Solution A and Solution B, the pink particles represent the solute. To figure out which solution has a higher concentration of pink particles, look at both the number of pink particles and the volume of the solvent in each container.
Use the concentration formula to find the number of pink particles per milliliter.
Solution B has more pink particles per milliliter. So, Solution B has a higher concentration of pink particles.


Question: Select the organism in the same species as the purple heron.

Choices:
- Caprimulgus europaeus
- Ardea purpurea
- Ardea herodias

This organism is a purple heron. Its scientific name is Ardea purpurea.

natural science

Use scientific names to classify organisms

Scientists use scientific names to identify organisms. Scientific names are made of two words.
The first word in an organism's scientific name tells you the organism's genus. A genus is a group of organisms that share many traits.
A genus is made up of one or more species. A species is a group of very similar organisms. The second word in an organism's scientific name tells you its species within its genus.
Together, the two parts of an organism's scientific name identify its species. For example Ursus maritimus and Ursus americanus are two species of bears. They are part of the same genus, Ursus. But they are different species within the genus. Ursus maritimus has the species name maritimus. Ursus americanus has the species name americanus.
Both bears have small round ears and sharp claws. But Ursus maritimus has white fur and Ursus americanus has black fur.

Solution:
A purple heron's scientific name is Ardea purpurea.
Ardea purpurea is in the same genus as Ardea herodias, but they are not in the same species.
Organisms in the same species have the same scientific names. Ardea purpurea and Ardea herodias are different species within the same genus.
Caprimulgus europaeus does not have the same scientific name as a purple heron. So, Ardea purpurea and Caprimulgus europaeus are not in the same species.
Ardea purpurea has the same scientific name as a purple heron. So, these organisms are in the same species.


Question: Which property do these three objects have in common?

Choices:
- transparent
- sour
- opaque

natural science

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it.
Different objects can have properties in common. You can use these properties to put objects into groups.

Solution:
Look at each object.
For each object, decide if it has that property.
A lemon has a sour taste. The glass bowl and the water are not sour.
You can see clearly through a transparent object. All three objects are transparent.
An opaque object does not let light through. None of the objects are opaque.
The property that all three objects have in common is transparent.


Question: Will these magnets attract or repel each other?

Choices:
- repel
- attract

Two magnets are placed as shown.

Hint: Magnets that attract pull together. Magnets that repel push apart.

natural science

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart.
Whether a magnet attracts or repels other magnets depends on the positions of its poles, or ends. Every magnet has two poles, called north and south.
Here are some examples of magnets. The north pole of each magnet is marked N, and the south pole is marked S.
If different poles are closest to each other, the magnets attract. The magnets in the pair below attract.
If the same poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

Solution:
Will these magnets attract or repel? To find out, look at which poles are closest to each other.
The south pole of one magnet is closest to the north pole of the other magnet. Poles that are different attract. So, these magnets will attract each other.


Question:
Complete the statement.
Potassium bromide is ().

Choices:
- an elementary substance
- a compound

The model below represents potassium bromide. In some countries, potassium bromide can be used as medicine to treat seizures.

natural science

Classify elementary substances and compounds using models

There are more than 100 different chemical elements, or types of atoms. Chemical elements make up all of the substances around you.
A substance may be composed of one chemical element or multiple chemical elements. Substances that are composed of only one chemical element are elementary substances. Substances that are composed of multiple chemical elements bonded together are compounds.
Every chemical element is represented by its own atomic symbol. An atomic symbol may consist of one capital letter, or it may consist of a capital letter followed by a lowercase letter. For example, the atomic symbol for the chemical element fluorine is F, and the atomic symbol for the chemical element beryllium is Be.
Scientists use different types of models to represent substances whose atoms are bonded in different ways. One type of model is a space-filling model. The space-filling model below represents the compound potassium chloride.
In a space-filling model, the balls represent atoms that are bonded together. Notice that the balls in the model above are not all the same color. Each color represents a different chemical element. The legend shows the color and the atomic symbol for each chemical element in the substance.

Solution:
Use the model to determine whether potassium bromide is an elementary substance or a compound.
Step 1: Interpret the model.
.
Use the legend to determine the chemical element represented by each color. The colors and atomic symbols from the legend are shown in the table below. The table also includes the names of the chemical elements represented in the model.
You can see from the model that potassium bromide is composed of potassium atoms and bromine atoms bonded together.
Step 2: Determine whether the substance is an elementary substance or a compound.
You know from Step 1 that potassium bromide is composed of two chemical elements: potassium and bromine. Since potassium bromide is composed of multiple chemical elements bonded together, potassium bromide is a compound.


Question: Compare the average kinetic energies of the particles in each sample. Which sample has the higher temperature?

Choices:
- sample B
- neither; the samples have the same temperature
- sample A

The diagrams below show two pure samples of gas in identical closed, rigid containers. Each colored ball represents one gas particle. Both samples have the same number of particles.

natural science

Identify how particle motion affects temperature and pressure

The temperature of a substance depends on the average kinetic energy of the particles in the substance. The higher the average kinetic energy of the particles, the higher the temperature of the substance.
The kinetic energy of a particle is determined by its mass and speed. For a pure substance, the greater the mass of each particle in the substance and the higher the average speed of the particles, the higher their average kinetic energy.

Solution:
Each particle in the two samples has the same mass, but the particles in sample A have a higher average speed than the particles in sample B. So, the particles in sample A have a higher average kinetic energy than the particles in sample B.
Because the particles in sample A have the higher average kinetic energy, sample A must have the higher temperature.


Question: Which of the following could Kaylee's test show?

Choices:
- whether different types of bacteria would need different nutrients to produce insulin
- whether she added enough nutrients to help the bacteria produce 20% more insulin
- whether producing more insulin would help the bacteria grow faster

People can use the engineering-design process to develop solutions to problems. One step in the process is testing if a potential solution meets the requirements of the design.
The passage below describes how the engineering-design process was used to test a solution to a problem. Read the passage. Then answer the question below.

People with diabetes sometimes take a medicine made from insulin. Insulin can be made by a special type of bacteria. Kaylee was a bioengineer who wanted to increase the amount of insulin that the bacteria produced by 20%. She read that giving the bacteria more nutrients could affect the amount of insulin they produced. So, Kaylee gave extra nutrients to some of the bacteria. Then, she measured how much insulin those bacteria produced compared to bacteria that did not get extra nutrients.
Figure: studying bacteria in a laboratory.

natural science

Evaluate tests of engineering-design solutions

People can use the engineering-design process to develop solutions to problems. One step in the process is testing if a potential solution meets the requirements of the design. How can you determine what a test can show? You need to figure out what was tested and what was measured.
Imagine an engineer needs to design a bridge for a windy location. She wants to make sure the bridge will not move too much in high wind. So, she builds a smaller prototype, or model, of a bridge. Then, she exposes the prototype to high winds and measures how much the bridge moves.
First, identify what was tested. A test can examine one design, or it may compare multiple prototypes to each other. In the test described above, the engineer tested a prototype of a bridge in high wind.
Then, identify what the test measured. One of the criteria for the bridge was that it not move too much in high winds. The test measured how much the prototype bridge moved.
Tests can show how well one or more designs meet the criteria. The test described above can show whether the bridge would move too much in high winds.


Question: Identify the question that Percy's experiment can best answer.

Choices:
- Can pennies hold more drops of water mixed with dish soap or water mixed with hand soap?
- Can pennies hold more drops of pure water or water mixed with hand soap?

The passage below describes an experiment. Read the passage and then follow the instructions below.

Percy used a dropper to put equal-sized drops of pure water, one at a time, onto a penny. The drops stayed together and formed a dome on the penny's surface. Percy recorded the number of drops he could add before the water spilled over the edge of the penny. Then, he rinsed and dried the penny, and repeated the test using water mixed with hand soap. He repeated these trials on nine additional pennies. Percy compared the average number of pure water drops to the average number of water drops mixed with hand soap that he could add to a penny before the water spilled over.
Figure: a dome of water on the surface of a penny.

natural science

Experiments can be designed to answer specific questions. How can you identify the questions that a certain experiment can answer? In order to do this, you need to figure out what was tested and what was measured during the experiment.
Imagine an experiment with two groups of daffodil plants. One group of plants was grown in sandy soil, and the other was grown in clay soil. Then, the height of each plant was measured.
First, identify the part of the experiment that was tested. The part of an experiment that is tested usually involves the part of the experimental setup that is different or changed. In the experiment described above, each group of plants was grown in a different type of soil. So, the effect of growing plants in different soil types was tested.
Then, identify the part of the experiment that was measured. The part of the experiment that is measured may include measurements and calculations. In the experiment described above, the heights of the plants in each group were measured.
Experiments can answer questions about how the part of the experiment that is tested affects the part that is measured. So, the experiment described above can answer questions about how soil type affects plant height.
Examples of questions that this experiment can answer include:
Does soil type affect the height of daffodil plants?
Do daffodil plants in sandy soil grow taller than daffodil plants in clay soil?
Are daffodil plants grown in sandy soil shorter than daffodil plants grown in clay soil?


Question: Which better describes the tide pool ecosystems in Tongue Point Marine Life Sanctuary?

Choices:
- It has no sunlight. It also has daily flooding and draining of seawater.
- It has daily flooding and draining of seawater. It also has many different types of organisms.

Figure: Tongue Point Marine Life Sanctuary.
Tongue Point Marine Life Sanctuary is in western Washington State. The park is on the coast of the Pacific Ocean. It has many tide pool ecosystems.

natural science

An ecosystem is formed when living and nonliving things interact in an environment. There are many types of ecosystems. Here are some ways in which ecosystems can differ from each other:
the pattern of weather, or climate
the type of soil or water
the organisms that live there

Solution: A tide pool is a type of ecosystem. Tide pool ecosystems have the following features: daily flooding and draining of seawater, water that is rich in nutrients, and many different types of organisms. So, the tide pool ecosystems in Tongue Point Marine Life Sanctuary have daily flooding and draining of seawater. They also have many different types of organisms.


Question: Identify the question that Zach's experiment can best answer.

Choices:
- Can pennies hold more drops of water mixed with dish soap or water mixed with hand soap?
- Can pennies hold more drops of pure water or water mixed with hand soap?

The passage below describes an experiment. Read the passage and then follow the instructions below.

Zach used a dropper to put equal-sized drops of pure water, one at a time, onto a penny. The drops stayed together and formed a dome on the penny's surface. Zach recorded the number of drops he could add before the water spilled over the edge of the penny. Then, he rinsed and dried the penny, and repeated the test using water mixed with hand soap. He repeated these trials on nine additional pennies. Zach compared the average number of pure water drops to the average number of water drops mixed with hand soap that he could add to a penny before the water spilled over.
Figure: a dome of water on the surface of a penny.

natural science

Experiments can be designed to answer specific questions. How can you identify the questions that a certain experiment can answer? In order to do this, you need to figure out what was tested and what was measured during the experiment.
Imagine an experiment with two groups of daffodil plants. One group of plants was grown in sandy soil, and the other was grown in clay soil. Then, the height of each plant was measured.
First, identify the part of the experiment that was tested. The part of an experiment that is tested usually involves the part of the experimental setup that is different or changed. In the experiment described above, each group of plants was grown in a different type of soil. So, the effect of growing plants in different soil types was tested.
Then, identify the part of the experiment that was measured. The part of the experiment that is measured may include measurements and calculations. In the experiment described above, the heights of the plants in each group were measured.
Experiments can answer questions about how the part of the experiment that is tested affects the part that is measured. So, the experiment described above can answer questions about how soil type affects plant height.
Examples of questions that this experiment can answer include:
Does soil type affect the height of daffodil plants?
Do daffodil plants in sandy soil grow taller than daffodil plants in clay soil?
Are daffodil plants grown in sandy soil shorter than daffodil plants grown in clay soil?


Question: What is the capital of Tennessee?

Choices:
- Knoxville
- Austin
- Biloxi
- Nashville

social science

Identify state capitals of the Southeast

Solution: Nashville is the capital of Tennessee.


Question: Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

Choices:
- The magnetic force is stronger in Pair 2.
- The magnetic force is stronger in Pair 1.
- The strength of the magnetic force is the same in both pairs.

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

natural science

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart.
These pulls and pushes between magnets are called magnetic forces. The stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.
You can change the strength of a magnetic force between two magnets by changing the distance between them. The magnetic force is stronger when the magnets are closer together.

Solution:
Distance affects the strength of the magnetic force. When magnets are closer together, the magnetic force between them is stronger.
The magnets in Pair 2 are closer together than the magnets in Pair 1. So, the magnetic force is stronger in Pair 2 than in Pair 1.


Question:
Complete the statement.
Chloroform is ().

Choices:
- a compound
- an elementary substance

The model below represents a molecule of chloroform. Chloroform was once used for pain relief. It is no longer used because it can be dangerous to humans.

natural science

Classify elementary substances and compounds using models

All substances are made of one or more chemical elements, or types of atoms. Substances that are made of only one chemical element are elementary substances. Substances that are made of two or more chemical elements bonded together are compounds.
Every chemical element is represented by its own symbol. For some elements, the symbol is one capital letter. For other elements, the symbol is one capital letter and one lowercase letter. For example, the symbol for the chemical element boron is B, and the symbol for the chemical element chlorine is Cl.
Scientists can use models to represent molecules. A ball-and-stick model of a molecule is shown below. This model represents a molecule of the compound boron trichloride.
In a ball-and-stick model, the balls represent atoms, and the sticks represent chemical bonds. Notice how each ball is labeled with a symbol for a chemical element. The ball represents one atom of that element.

Solution:
Count the number of chemical elements represented in the model. Then, decide if chloroform is an elementary substance or a compound.
In this model, each ball is labeled with C for carbon, H for hydrogen, or Cl for chlorine. So, the model shows you that chloroform is made of three chemical elements bonded together.
Substances made of two or more chemical elements bonded together are compounds. So, chloroform is a compound.


Question: Is hornblende a mineral or a rock?

Choices:
- rock
- mineral

Hornblende has the following properties:
found in nature
pure substance
dull luster
fixed crystal structure
solid
not made by organisms

natural science

Minerals are the building blocks of rocks. A rock can be made of one or more minerals.
Minerals and rocks have the following properties:
Property | Mineral | Rock
It is a solid. | Yes | Yes
It is formed in nature. | Yes | Yes
It is not made by organisms. | Yes | Yes
It is a pure substance. | Yes | No
It has a fixed crystal structure. | Yes | No
You can use these properties to tell whether a substance is a mineral, a rock, or neither.
Look closely at the last three properties:
Minerals and rocks are not made by organisms.
Organisms make their own body parts. For example, snails and clams make their shells. Because they are made by organisms, body parts cannot be  minerals or rocks.
Humans are organisms too. So, substances that humans make by hand or in factories are not minerals or rocks.
A mineral is a pure substance, but a rock is not.
A pure substance is made of only one type of matter.  Minerals are pure substances, but rocks are not. Instead, all rocks are mixtures.
A mineral has a fixed crystal structure, but a rock does not.
The crystal structure of a substance tells you how the atoms or molecules in the substance are arranged. Different types of minerals have different crystal structures, but all minerals have a fixed crystal structure. This means that the atoms and molecules in different pieces of the same type of mineral are always arranged the same way.
However, rocks do not have a fixed crystal structure. So, the arrangement of atoms or molecules in different pieces of the same type of rock may be different!

Solution: Hornblende has all the properties of a mineral. So, hornblende is a mineral.


Question:
Is the following statement about our solar system true or false?
The volume of Neptune is less than 75% of the volume of Uranus.

Choices:
- false
- true

Use the data to answer the question below.

natural science

Analyze data to compare properties of planets

A planet's volume tells you the size of the planet.
The primary composition of a planet is what the planet is made mainly of. In our solar system, planets are made mainly of rock, gas, or ice.

Solution:
To determine if this statement is true, calculate the value of 75% of the volume of Uranus by multiplying its volume by 0.75.
Then compare the result to the volume of Neptune. The volume of Neptune is 62,530 billion km^3, which is more than 51,248 billion km^3. So, the volume of Neptune is more than 75% of the volume of Uranus.


Question: Identify the question that Mike's experiment can best answer.

Choices:
- Do more bacteria grow in liquid with cinnamon than in liquid without cinnamon?
- Does temperature affect how much bacteria can grow in liquid?

The passage below describes an experiment. Read the passage and then follow the instructions below.

Mike mixed bacteria into a nutrient-rich liquid where the bacteria could grow. He poured four ounces of the mixture into each of ten glass flasks. In five of the ten flasks, he also added one teaspoon of cinnamon. He allowed the bacteria in the flasks to grow overnight in a 37°C room. Then, Mike used a microscope to count the number of bacteria in a small sample from each flask. He compared the amount of bacteria in the liquid with cinnamon to the amount of bacteria in the liquid without cinnamon.
Figure: flasks of liquid for growing bacteria.

natural science

Experiments can be designed to answer specific questions. How can you identify the questions that a certain experiment can answer? In order to do this, you need to figure out what was tested and what was measured during the experiment.
Imagine an experiment with two groups of daffodil plants. One group of plants was grown in sandy soil, and the other was grown in clay soil. Then, the height of each plant was measured.
First, identify the part of the experiment that was tested. The part of an experiment that is tested usually involves the part of the experimental setup that is different or changed. In the experiment described above, each group of plants was grown in a different type of soil. So, the effect of growing plants in different soil types was tested.
Then, identify the part of the experiment that was measured. The part of the experiment that is measured may include measurements and calculations. In the experiment described above, the heights of the plants in each group were measured.
Experiments can answer questions about how the part of the experiment that is tested affects the part that is measured. So, the experiment described above can answer questions about how soil type affects plant height.
Examples of questions that this experiment can answer include:
Does soil type affect the height of daffodil plants?
Do daffodil plants in sandy soil grow taller than daffodil plants in clay soil?
Are daffodil plants grown in sandy soil shorter than daffodil plants grown in clay soil?


Question: What is the capital of Utah?

Choices:
- Salt Lake City
- Nashville
- Boston
- Salem

social science

Solution: Salt Lake City is the capital of Utah.


Question: Which animal is also adapted to use its neck to appear large and scary to a predator?

Choices:
- Madagascar day gecko
- Mozambique spitting cobra

Bearded dragons are lizards. Their predators include owls, eagles, and snakes. The  uses its neck to appear large and scary to a predator.
Figure: bearded dragon.

natural science

Animal adaptations: beaks, mouths, and necks

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors.
The shape of an animal's neck is one example of an adaptation. Animals' necks can be adapted in different ways. For example, a large frilled neck might help an animal appear dangerous to its predators. A long neck might help an animal get food from tall trees.

Solution:
Look at the picture of the bearded dragon.
When frightened, the bearded dragon can spread out its hood to appear larger and more dangerous. If a predator is nearby, the hood can help scare it away.
Now look at each animal. Figure out which animal has a similar adaptation.
The Mozambique spitting cobra has a hood around its neck. It uses its neck to appear larger and more dangerous to a predator.
The Madagascar day gecko has a short neck. Its neck is not adapted to help it appear larger and more dangerous to a predator.


Question: What is the capital of Colorado?

Choices:
- Boulder
- Colorado Springs
- Dallas
- Denver

social science

Solution: Denver is the capital of Colorado.


Question: Which property do these three objects have in common?

Choices:
- shiny
- rough
- fragile

natural science

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it.
Different objects can have properties in common. You can use these properties to put objects into groups.

Solution:
Look at each object.
For each object, decide if it has that property.
A shiny object reflects a lot of light. You can usually see your reflection in a shiny object. All three objects are shiny.
A fragile object will break into pieces if you drop it. The car bumper and the gold ring are not fragile.
A rough object feels scratchy when you touch it. The car bumper and the gold ring are not rough.
The property that all three objects have in common is shiny.


Question: Select the true statement.

Choices:
- Animals need food, but plants don't.
- Chemical energy can be used for cell growth.

Plants, animals, and all other organisms need energy from food to live and grow.

How do organisms get energy from food? Inside an organism's cells, food molecules are broken down and rearranged through chemical reactions. The reactions release chemical energy that the cells can use to power growth and other important cell processes. These processes allow the entire organism to live and grow.
Figure: a bear getting food.

natural science

Solution:
Chemical energy can be used for cell growth.
Cells can use chemical energy to power many important cell processes, including growth.
Animals need food, but plants don't.
All organisms need energy from food. Some organisms, including most plants, make their own food.
Molecules from food can provide energy.
In cells, food molecules are broken down and rearranged. These changes release chemical energy.


Question: Identify the question that Tanvi's experiment can best answer.

Choices:
- Are eggs more likely to float in fresh water or salty water?
- Does the amount of water in a glass affect whether eggs sink or float in the water?

The passage below describes an experiment. Read the passage and then follow the instructions below.

Tanvi poured four ounces of water into each of six glasses. Tanvi dissolved one tablespoon of salt in each of three glasses, and did not add salt to the other three. Then, Tanvi placed an egg in one glass and observed if the egg floated. She removed the egg and dried it. She repeated the process with the other five glasses, recording each time if the egg floated. Tanvi repeated this test with two more eggs and counted the number of times the eggs floated in fresh water compared to salty water.
Figure: an egg floating in a glass of salty water.

natural science

Experiments can be designed to answer specific questions. How can you identify the questions that a certain experiment can answer? In order to do this, you need to figure out what was tested and what was measured during the experiment.
Imagine an experiment with two groups of daffodil plants. One group of plants was grown in sandy soil, and the other was grown in clay soil. Then, the height of each plant was measured.
First, identify the part of the experiment that was tested. The part of an experiment that is tested usually involves the part of the experimental setup that is different or changed. In the experiment described above, each group of plants was grown in a different type of soil. So, the effect of growing plants in different soil types was tested.
Then, identify the part of the experiment that was measured. The part of the experiment that is measured may include measurements and calculations. In the experiment described above, the heights of the plants in each group were measured.
Experiments can answer questions about how the part of the experiment that is tested affects the part that is measured. So, the experiment described above can answer questions about how soil type affects plant height.
Examples of questions that this experiment can answer include:
Does soil type affect the height of daffodil plants?
Do daffodil plants in sandy soil grow taller than daffodil plants in clay soil?
Are daffodil plants grown in sandy soil shorter than daffodil plants grown in clay soil?


Question: Which part of the pineapple tree do we usually eat?

Choices:
- the leaves
- the root
- the fruit

People use pineapple trees for food. We usually eat the part of this plant that contains the seeds. It grows from a pollinated flower.

natural science

Classify fruits and vegetables as plant parts

The fruits and vegetables we eat are parts of plants! Plants are made up of different structures. The different structures carry out important functions.
The roots take in water and nutrients from the soil. They also hold the plant in place in the soil.
The stem supports the plant. It carries food, water, and nutrients through the plant.
The leaves are where most of the plant's photosynthesis happens. Photosynthesis is the process plants use to turn water, sunlight, and carbon dioxide into food.
After they are pollinated, the flowers make seeds and fruit.
The fruit contain the seeds. Each fruit grows from a pollinated flower.
The seeds can grow into a new plant. Germination is when a seed begins to grow.

Solution: The part of the pineapple tree we usually eat is the fruit. It contains the seeds.


Question: Which solution has a higher concentration of purple particles?

Choices:
- Solution B
- neither; their concentrations are the same
- Solution A

The diagram below is a model of two solutions. Each purple ball represents one particle of solute.

natural science

A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent.
The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent.
concentration = particles of solute / volume of solvent

Solution:
In Solution A and Solution B, the purple particles represent the solute. To figure out which solution has a higher concentration of purple particles, look at both the number of purple particles and the volume of the solvent in each container.
Use the concentration formula to find the number of purple particles per milliliter.
Solution A and Solution B have the same number of purple particles per milliliter. So, their concentrations are the same.


Question: Which statement describes the Peary Land ecosystem?

Choices:
- It has warm summers and cool winters.
- It has many evergreen trees.
- It has mostly small plants.

Figure: Peary Land.
Peary Land is a tundra ecosystem in northern Greenland. It is part of Northeast Greenland National Park. That park is one of the largest national parks in the world, covering about 375,000 square miles.

natural science

An environment includes all of the biotic, or living, and abiotic, or nonliving, things in an area. An ecosystem is created by the relationships that form among the biotic and abiotic parts of an environment.
There are many different types of terrestrial, or land-based, ecosystems. Here are some ways in which terrestrial ecosystems can differ from each other:
the pattern of weather, or climate
the type of soil
the organisms that live there

Solution: A tundra is a type of ecosystem. Tundras have the following features: long, cold winters and short, cold summers, soil that is frozen year-round, and mostly small plants. So, the following statement describes the Peary Land ecosystem: long, cold winters and short, cold summers, soil that is frozen year-round, and mostly small plants. It has mostly small plants. The following statements do not describe Peary Land: long, cold winters and short, cold summers, soil that is frozen year-round, and mostly small plants. It has warm summers and cool winters. It has many evergreen trees.


Question: Which ocean is highlighted?

Choices:
- the Atlantic Ocean
- the Indian Ocean
- the Southern Ocean
- the Arctic Ocean

social science

Oceans are huge bodies of salt water. The world has five oceans. All of the oceans are connected, making one world ocean.

Solution: This is the Atlantic Ocean.


Question: Which of these states is farthest east?

Choices:
- New York
- Ohio
- Colorado
- Mississippi

social science

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west.
A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction.
The north arrow points to the North Pole. On most maps, north is at the top of the map.

Solution: To find the answer, look at the compass rose. Look at which way the east arrow is pointing. New York is farthest east.


Question: What is the expected ratio of offspring with dumbo ears to offspring with normal ears? Choose the most likely ratio.

Choices:
- 3:1
- 0:4
- 2:2
- 4:0
- 1:3

This passage describes the ear type trait in rats:
Some rats have dumbo ears, which are larger and rounder than normal ears. Dumbo ears are also set on the sides of the rat's head instead of on the top. The word dumbo comes from the name of a cartoon elephant whose ears had a similar appearance.
In a group of rats, some individuals have normal ears and others have dumbo ears. In this group, the gene for the ear type trait has two alleles. The allele for normal ears (E) is dominant over the allele for dumbo ears (e).
This Punnett square shows a cross between two rats.

natural science

Use Punnett squares to calculate ratios of offspring types

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
A Punnett square shows what types of offspring a cross can produce. The expected ratio of offspring types compares how often the cross produces each type of offspring, on average. To write this ratio, count the number of boxes in the Punnett square representing each type.
For example, consider the Punnett square below.
 | F | f
F | FF | Ff
f | Ff | ff
There is 1 box with the genotype FF and 2 boxes with the genotype Ff. So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.

Solution:
To determine how many boxes in the Punnett square represent offspring with dumbo ears or normal ears, consider whether each phenotype is the dominant or recessive allele's version of the ear type trait. The question tells you that the E allele, which is for normal ears, is dominant over the e allele, which is for dumbo ears.
Dumbo ears is the recessive allele's version of the ear type trait. A rat with the recessive version of the ear type trait must have only recessive alleles for the ear type gene. So, offspring with dumbo ears must have the genotype ee.
There are 0 boxes in the Punnett square with the genotype ee.
Normal ears is the dominant allele's version of the ear type trait. A rat with the dominant version of the ear type trait must have at least one dominant allele for the ear type gene. So, offspring with normal ears must have the genotype EE or Ee.
All 4 boxes in the Punnett square have the genotype EE or Ee.
So, the expected ratio of offspring with dumbo ears to offspring with normal ears is 0:4. This means that, based on the Punnett square, this cross will never produce offspring with dumbo ears. Instead, this cross is expected to always produce offspring with normal ears.


Question: Which is this organism's scientific name?

Choices:
- European nightjar
- Caprimulgus europaeus

This organism is Caprimulgus europaeus. It is also called a European nightjar.

natural science

An organism's common name is the name that people normally call the organism. Common names often contain words you know.
An organism's scientific name is the name scientists use to identify the organism. Scientific names often contain words that are not used in everyday English.
Scientific names are written in italics, but common names are usually not. The first word of the scientific name is capitalized, and the second word is not. For example, the common name of the animal below is giant panda. Its scientific name is Ailuropoda melanoleuca.

Solution:
Caprimulgus europaeus is written in italics. The first word is capitalized, and the second word is not.
So, Caprimulgus europaeus is the scientific name.


Question: Which material are these marbles made of?

Choices:
- glass
- cardboard

natural science

A material is a type of matter. Wood, glass, metal, and plastic are common materials.

Solution:
Look at the picture of the marbles.
The marbles are made of glass.
How are marbles made? First, glass is heated until it gets very soft. Next, the soft glass is rolled into balls. The glass balls slowly cool and form marbles.


Question: Which of these states is farthest west?

Choices:
- Delaware
- Florida
- Rhode Island
- Maine

social science

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west.
A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction.
The north arrow points to the North Pole. On most maps, north is at the top of the map.

Solution: To find the answer, look at the compass rose. Look at which way the west arrow is pointing. Florida is farthest west.


Question: Which animal's neck is also adapted for reaching high branches?

Choices:
- bison
- giraffe

Gerenuk eat leaves and twigs. The 's neck is adapted for reaching branches that are high above the ground.
Figure: gerenuk.

natural science

Animal adaptations: beaks, mouths, and necks

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors.
The shape of an animal's neck is one example of an adaptation. Animals' necks can be adapted in different ways. For example, a large frilled neck might help an animal appear dangerous to its predators. A long neck might help an animal get food from tall trees.

Solution:
Look at the picture of the gerenuk.
Now look at each animal. Figure out which animal has a similar adaptation.
The giraffe has a long neck. Its neck is adapted for reaching high branches.
The bison has a short neck. Its neck is not adapted for reaching high branches. The bison eats mostly grass.


Question: What is the capital of Utah?

Choices:
- Richmond
- Provo
- Phoenix
- Salt Lake City

social science

Solution: Salt Lake City is the capital of Utah.


Question: Which ocean is highlighted?

Choices:
- the Pacific Ocean
- the Arctic Ocean
- the Indian Ocean
- the Atlantic Ocean

social science

Oceans are huge bodies of salt water. The world has five oceans. All of the oceans are connected, making one world ocean.

Solution: This is the Pacific Ocean.


Question: Which property matches this object?

Choices:
- transparent
- bouncy

natural science

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it.

Solution:
Look at the object.
Think about each property.
A bouncy object will bounce back from the floor if you drop it. The glass bottle is not bouncy.
You can see clearly through a transparent object. The glass bottle is transparent.


Question:
Complete the text to describe the diagram.
Solute particles moved in both directions across the permeable membrane. But more solute particles moved across the membrane (). When there was an equal concentration on both sides, the particles reached equilibrium.

Choices:
- to the right than to the left
- to the left than to the right

The diagram below shows a solution with one solute. Each solute particle is represented by a yellow ball. The solution fills a closed container that is divided in half by a membrane. The membrane, represented by a dotted line, is permeable to the solute particles.
The diagram shows how the solution can change over time during the process of diffusion.

natural science

In a solution, solute particles move and spread throughout the solvent. The diagram below shows how a solution can change over time. Solute particles move from the area where they are at a higher concentration to the area where they are at a lower concentration. This movement happens through the process of diffusion.
As a result of diffusion, the concentration of solute particles becomes equal throughout the solution. When this happens, the solute particles reach equilibrium. At equilibrium, the solute particles do not stop moving. But their concentration throughout the solution stays the same.
Membranes, or thin boundaries, can divide solutions into parts. A membrane is permeable to a solute when particles of the solute can pass through gaps in the membrane. In this case, solute particles can move freely across the membrane from one side to the other.
So, for the solute particles to reach equilibrium, more particles will move across a permeable membrane from the side with a higher concentration of solute particles to the side with a lower concentration. At equilibrium, the concentration on both sides of the membrane is equal.

Solution:
Look at the diagram again. It shows you how the solution changed during the process of diffusion.
Before the solute particles reached equilibrium, there were 6 solute particles on the left side of the membrane and 2 solute particles on the right side of the membrane.
When the solute particles reached equilibrium, there were 4 solute particles on each side of the membrane. There were 2 more solute particles on the right side of the membrane than before.
So, for the solute particles to reach equilibrium, more solute particles must have moved across the membrane to the right than to the left.


Question: Which solution has a higher concentration of yellow particles?

Choices:
- neither; their concentrations are the same
- Solution A
- Solution B

The diagram below is a model of two solutions. Each yellow ball represents one particle of solute.

natural science

A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent.
The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent.
concentration = particles of solute / volume of solvent

Solution:
In Solution A and Solution B, the yellow particles represent the solute. To figure out which solution has a higher concentration of yellow particles, look at both the number of yellow particles and the volume of the solvent in each container.
Use the concentration formula to find the number of yellow particles per milliliter.
Solution B has more yellow particles per milliliter. So, Solution B has a higher concentration of yellow particles.


Question: What can Neil and Darnell trade to each get what they want?

Choices:
- Darnell can trade his almonds for Neil's tomatoes.
- Darnell can trade his broccoli for Neil's oranges.
- Neil can trade his tomatoes for Darnell's sandwich.
- Neil can trade his tomatoes for Darnell's broccoli.

Trade happens when people agree to exchange goods and services. People give up something to get something else. Sometimes people barter, or directly exchange one good or service for another.
Neil and Darnell open their lunch boxes in the school cafeteria. Both of them could be happier with their lunches. Neil wanted broccoli in his lunch and Darnell was hoping for tomatoes. Look at the images of their lunches. Then answer the question below.

social science

Solution:
Neil wanted broccoli in his lunch and Darnell was hoping for tomatoes. Look at the labeled part of the images.
Neil has tomatoes. Darnell has broccoli. They can trade tomatoes for broccoli to both be happier. Trading other things would not help either person get more items they want.


Question: What is the capital of Washington?

Choices:
- Olympia
- Salt Lake City
- Nampa
- Springfield

social science

Solution: Olympia is the capital of Washington.


Question: Which country is highlighted?

Choices:
- Papua New Guinea
- New Zealand
- Australia
- Nauru

social science

Identify and select countries of Oceania

Solution: This country is New Zealand.


Question: Will these magnets attract or repel each other?

Choices:
- repel
- attract

natural science

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart.
Whether a magnet attracts or repels other magnets depends on the positions of its poles, or ends. Every magnet has two poles: north and south.
Here are some examples of magnets. The north pole of each magnet is labeled N, and the south pole is labeled S.
If opposite poles are closest to each other, the magnets attract. The magnets in the pair below attract.
If the same, or like, poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

Solution:
To predict if these magnets will attract or repel, look at which poles are closest to each other.
The south pole of one magnet is closest to the south pole of the other magnet. Like poles repel. So, these magnets will repel each other.


Question: Which of these states is farthest north?

Choices:
- Georgia
- Kentucky
- New Mexico
- Arkansas

social science

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west.
A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction.
The north arrow points to the North Pole. On most maps, north is at the top of the map.

Solution: To find the answer, look at the compass rose. Look at which way the north arrow is pointing. Kentucky is farthest north.


Question: What can Jennifer and Melissa trade to each get what they want?

Choices:
- Jennifer can trade her tomatoes for Melissa's carrots.
- Melissa can trade her broccoli for Jennifer's oranges.
- Melissa can trade her almonds for Jennifer's tomatoes.
- Jennifer can trade her tomatoes for Melissa's broccoli.

Trade happens when people agree to exchange goods and services. People give up something to get something else. Sometimes people barter, or directly exchange one good or service for another.
Jennifer and Melissa open their lunch boxes in the school cafeteria. Neither Jennifer nor Melissa got everything that they wanted. The table below shows which items they each wanted:

Look at the images of their lunches. Then answer the question below.
Jennifer's lunch Melissa's lunch

social science

Solution:
Look at the table and images.
Jennifer wants broccoli. Melissa wants tomatoes. They can trade tomatoes for broccoli to both get what they want. Trading other things would not help both people get more items they want.


Question: Can Rhizophora mangle cells make their own food?

Choices:
- no
- yes

This organism is Rhizophora mangle. It is a member of the plant kingdom.
Rhizophora mangle is commonly called a red mangrove. Red mangrove trees grow in or near water. They have strong roots that help prop, or hold, them up. These roots are also aerial, which means that they can grow above the ground. So, the red mangrove roots are called aerial prop roots.

natural science

Describe, classify, and compare kingdoms

In the past, scientists classified living organisms into two groups: plants and animals. Over the past 300 years, scientists have discovered many more types of organisms. Today, many scientists classify organisms into six broad groups, called kingdoms.
Organisms in each kingdom have specific traits. The table below shows some traits used to describe each kingdom.
 | Bacteria | Archaea | Protists | Fungi | Animals | Plants
How many cells do they have? | one | one | one or many | one or many | many | many
Do their cells have a nucleus? | no | no | yes | yes | yes | yes
Can their cells make food? | some species can | some species can | some species can | no | no | yes

Solution: Rhizophora mangle is a plant. Plant cells can make their own food. Plant cells make food using photosynthesis.


Question: Which property do these four objects have in common?

Choices:
- smooth
- translucent
- transparent

natural science

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it.
Different objects can have properties in common. You can use these properties to put objects into groups. Grouping objects by their properties is called classification.

Solution:
Look at each object.
For each object, decide if it has that property.
A translucent object lets light through. But you cannot see clearly through a translucent object. The rubber ball and the silver ring are not translucent.
You can see clearly through a transparent object. The magnifying glass is transparent, but the rubber ball and the silver ring are not.
A smooth object is not scratchy or rough. All four objects are smooth.
The property that all four objects have in common is smooth.


Question: Which statement describes the Tibetan Plateau ecosystem?

Choices:
- It has warm summers and cool winters.
- It has soil that is frozen year-round.

Figure: Tibetan Plateau.
The Tibetan Plateau is a tundra ecosystem located in Tibet, western China, and northern India. The plateau is over 14,800 feet high and is surrounded by many mountain ranges.

natural science

An environment includes all of the biotic, or living, and abiotic, or nonliving, things in an area. An ecosystem is created by the relationships that form among the biotic and abiotic parts of an environment.
There are many different types of terrestrial, or land-based, ecosystems. Here are some ways in which terrestrial ecosystems can differ from each other:
the pattern of weather, or climate
the type of soil
the organisms that live there

Solution: A tundra is a type of ecosystem. Tundras have the following features: long, cold winters and short, cold summers, soil that is frozen year-round, and mostly small plants. So, the following statements describe the Tibetan Plateau ecosystem: long, cold winters and short, cold summers, soil that is frozen year-round, and mostly small plants. It has soil that is frozen year-round. It has mostly small plants. The following statement does not describe the Tibetan Plateau: long, cold winters and short, cold summers, soil that is frozen year-round, and mostly small plants. It has warm summers and cool winters.


Question: Which of the following best describes a community in the Great Sand Dunes?

Choices:
- the grasses and the prairie sunflowers
- the Ord's kangaroo rats
- the grasses, the water, and the sand dunes

Read the passage. Then answer the question below.

The tallest sand dunes in North America are in Colorado. In this desert region, the top few inches of sand are usually dry, but the lower layers remain moist year-round.
Ord's kangaroo rats spend their entire lives in these dunes. They collect seeds from grasses and prairie sunflowers, and then bury the seeds in the moist layers of sand. Later, the rats come back to eat their buried seeds. The seeds absorb enough moisture from the sand that the kangaroo rats never need to drink water!
Figure: Great Sand Dunes National Park and Preserve in Colorado.

natural science

Describe populations, communities, and ecosystems

In an environment, organisms interact with each other and with their nonliving surroundings. To help describe these interactions, ecologists use specific terms for different types of groups.
A single organism is an individual. Individuals of the same species that live in the same place are part of a population.
Multiple populations of different species that live in the same place are part of a community.
Together, communities of living organisms and the nonliving parts of their environment make up an ecosystem.


Question: Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

Choices:
- The magnetic force is stronger in Pair 2.
- The magnetic force is stronger in Pair 1.
- The strength of the magnetic force is the same in both pairs.

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material.

natural science

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart.
These pulls and pushes between magnets are called magnetic forces. The stronger the magnetic force between two magnets, the more strongly the magnets attract or repel each other.
You can change the strength of a magnetic force between two magnets by changing the distance between them. The magnetic force is stronger when the magnets are closer together.

Solution:
Distance affects the strength of the magnetic force. When magnets are closer together, the magnetic force between them is stronger.
The magnets in Pair 1 are closer together than the magnets in Pair 2. So, the magnetic force is stronger in Pair 1 than in Pair 2.


Question: Which solution has a higher concentration of yellow particles?

Choices:
- Solution A
- Solution B
- neither; their concentrations are the same

The diagram below is a model of two solutions. Each yellow ball represents one particle of solute.

natural science

A solution is made up of two or more substances that are completely mixed. In a solution, solute particles are mixed into a solvent. The solute cannot be separated from the solvent by a filter. For example, if you stir a spoonful of salt into a cup of water, the salt will mix into the water to make a saltwater solution. In this case, the salt is the solute. The water is the solvent.
The concentration of a solute in a solution is a measure of the ratio of solute to solvent. Concentration can be described in terms of particles of solute per volume of solvent.
concentration = particles of solute / volume of solvent

Solution:
In Solution A and Solution B, the yellow particles represent the solute. To figure out which solution has a higher concentration of yellow particles, look at both the number of yellow particles and the volume of the solvent in each container.
Use the concentration formula to find the number of yellow particles per milliliter.
Solution A has more yellow particles per milliliter. So, Solution A has a higher concentration of yellow particles.


Question: What is the capital of Florida?

Choices:
- Oklahoma City
- Orlando
- Tallahassee
- Tampa

social science

Identify state capitals of the Southeast

Solution: Tallahassee is the capital of Florida.


Question: Which animal is also adapted for climbing trees?

Choices:
- bare-eared squirrel monkey
- chital

Crested black macaques live in the rain forests of Indonesia. They climb trees to find food and shelter. The macaque's hands and feet are adapted for climbing trees.
Figure: crested black macaque.

natural science

An adaptation is an inherited trait that helps an organism survive or reproduce. Adaptations can include both body parts and behaviors.
The shape of an animal's feet is one example of an adaptation. Animals' feet can be adapted in different ways. For example, webbed feet might help an animal swim. Feet with thick fur might help an animal walk on cold, snowy ground.

Solution:
Look at the picture of the crested black macaque.
The crested black macaque has long fingers and toes. It is adapted for climbing trees. The crested black macaque uses its long fingers and toes to hold on to branches while climbing.
Now look at each animal. Figure out which animal has a similar adaptation.
The bare-eared squirrel monkey has long fingers and toes. It is adapted for climbing trees.
The chital has four hoofed feet. It is not adapted for climbing trees. The chital uses its feet to walk and run.


Question: Think about the magnetic force between the magnets in each pair. Which of the following statements is true?

Choices:
- The magnitude of the magnetic force is the same in both pairs.
- The magnitude of the magnetic force is smaller in Pair 2.
- The magnitude of the magnetic force is smaller in Pair 1.

The images below show two pairs of magnets. The magnets in different pairs do not affect each other. All the magnets shown are made of the same material, but some of them are different sizes.

natural science

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart. These pulls and pushes between magnets are called magnetic forces.
The strength of a force is called its magnitude. The greater the magnitude of the magnetic force between two magnets, the more strongly the magnets attract or repel each other.
You can change the magnitude of a magnetic force between two magnets by using magnets of different sizes. The magnitude of the magnetic force is smaller when the magnets are smaller.

Solution:
Magnet sizes affect the magnitude of the magnetic force. Imagine magnets that are the same shape and made of the same material. The smaller the magnets, the smaller the magnitude of the magnetic force between them.
Magnet A is the same size in both pairs. But Magnet B is smaller in Pair 1 than in Pair 2. So, the magnitude of the magnetic force is smaller in Pair 1 than in Pair 2.


Question: During this time, thermal energy was transferred from () to ().

Choices:
- each salmon . . . the surroundings
- the surroundings . . . each salmon

Ryan lit the charcoal in his grill to cook two identical salmon. He put one fish on the left half of the grill and one fish on the right half of the grill. This table shows how the temperature of each salmon changed over 6minutes.

natural science

A change in an object's temperature indicates a change in the object's thermal energy:
An increase in temperature shows that the object's thermal energy increased. So, thermal energy was transferred into the object from its surroundings.
A decrease in temperature shows that the object's thermal energy decreased. So, thermal energy was transferred out of the object to its surroundings.

Solution: The temperature of each salmon increased, which means that the thermal energy of each salmon increased. So, thermal energy was transferred from the surroundings to each salmon.


Question: Which statement is true about the average monthly precipitation in Charlotte?

Choices:
- January is the month with the highest average precipitation.
- Precipitation does not change much from month to month.
- Charlotte has a rainy season and a dry season.

Use the graph to answer the question below.

natural science

Scientists record climate data from places around the world. Precipitation, or rain and snow, is one type of climate data. Scientists collect data over many years. They can use this data to calculate the average precipitation for each month. The average precipitation can be used to describe the climate of a location.
A bar graph can be used to show the average amount of precipitation each month. Months with taller bars have more precipitation on average.

Solution:
To describe the average precipitation trends in Charlotte, look at the graph.
Choice "Jan" is incorrect.
Choice "Charlotte has a rainy season and a dry season." is incorrect.
The average monthly precipitation does not change much throughout the year. Every month has some rain, and there is no dry season. So, Charlotte does not have a rainy season and a dry season.
Choice "January is the month with the highest average precipitation." is incorrect.
Several other months have a slightly higher average precipitation than January.
Choice "Precipitation does not change much from month to month." is incorrect.
The average monthly precipitation changes only slightly throughout the year.


Question: Which of these states is farthest south?

Choices:
- Michigan
- New York
- North Dakota
- California

social science

Maps have four cardinal directions, or main directions. Those directions are north, south, east, and west.
A compass rose is a set of arrows that point to the cardinal directions. A compass rose usually shows only the first letter of each cardinal direction.
The north arrow points to the North Pole. On most maps, north is at the top of the map.

Solution: To find the answer, look at the compass rose. Look at which way the south arrow is pointing. California is farthest south.


Question: Which country is highlighted?

Choices:
- Kiribati
- Solomon Islands
- the Marshall Islands
- the Federated States of Micronesia

social science

Identify and select countries of Oceania

Solution:
This country is the Marshall Islands.
Does the Marshall Islands have any territorial disputes?
The Marshall Islands claims to own Wake Island, which is a disputed territory. In other words, multiple countries or groups claim that the area rightfully belongs to them.
The United States claimed Wake Island in 1899 and has controlled it since then. But the Marshall Islands considers the island part of its territory. It says that its people have traveled to the island to gather food and resources for many years. Today, the island is mainly used by the U.S. Air Force.


Question: Is granite a mineral?

Choices:
- no
- yes

Granite has the following properties:
not made by living things
no fixed crystal structure
naturally occurring
not a pure substance
solid

natural science

Properties are used to identify different substances. Minerals have the following properties:
It is a solid.
It is formed in nature.
It is not made by organisms.
It is a pure substance.
It has a fixed crystal structure.
If a substance has all five of these properties, then it is a mineral.
Look closely at the last three properties:
A mineral is not made by organisms.
Organisms make their own body parts. For example, snails and clams make their shells. Because they are made by organisms, body parts cannot be minerals.
Humans are organisms too. So, substances that humans make by hand or in factories cannot be minerals.
A mineral is a pure substance.
A pure substance is made of only one type of matter. All minerals are pure substances.
A mineral has a fixed crystal structure.
The crystal structure of a substance tells you how the atoms or molecules in the substance are arranged. Different types of minerals have different crystal structures, but all minerals have a fixed crystal structure. This means that the atoms or molecules in different pieces of the same type of mineral are always arranged the same way.

Solution: Granite does not have all the properties of a mineral. So, granite is not a mineral.


Question: Which property do these three objects have in common?

Choices:
- sticky
- bouncy
- stretchy

natural science

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells. Properties can also tell you how an object will behave when something happens to it.
Different objects can have properties in common. You can use these properties to put objects into groups.

Solution:
Look at each object.
For each object, decide if it has that property.
A sticky object can attach or stick to other things. All three objects are sticky.
A stretchy object gets longer when you pull on it. The ice cream sundae and the ice pop are not stretchy.
A bouncy object will bounce back from the floor if you drop it. None of the objects are bouncy.
The property that all three objects have in common is sticky.


Question: What is the capital of Tennessee?

Choices:
- Nashville
- Knoxville
- Memphis
- Indianapolis

social science

Identify state capitals of the Southeast

Solution: Nashville is the capital of Tennessee.


Question: What is the capital of Mississippi?

Choices:
- Harrisburg
- Biloxi
- Jackson
- Rapid City

social science

Identify state capitals of the Southeast

Solution: Jackson is the capital of Mississippi.


Question: What is the capital of Georgia?

Choices:
- Augusta
- Lincoln
- Jackson
- Atlanta

social science

Identify state capitals of the Southeast

Solution: Atlanta is the capital of Georgia.


Question: What is the capital of Maine?

Choices:
- Montpelier
- Providence
- Augusta
- Portland

social science

Identify state capitals of the Northeast

Solution: Augusta is the capital of Maine.


Question: Which property do these two objects have in common?

Choices:
- sticky
- salty

natural science

An object has different properties. A property of an object can tell you how it looks, feels, tastes, or smells.
Different objects can have the same properties. You can use these properties to put objects into groups.

Solution:
Look at each object.
For each object, decide if it has that property.
Potato chips have a salty taste. Both objects are salty.
A sticky object can stick to other things. Neither of the objects are sticky.
The property that both objects have in common is salty.


Question: What is the capital of Indiana?

Choices:
- Indianapolis
- Lansing
- Fort Wayne
- Springfield

social science

Solution: Indianapolis is the capital of Indiana.


Question: Is granite a mineral or a rock?

Choices:
- mineral
- rock

Granite has the following properties:
no fixed crystal structure
not made by organisms
solid
not a pure substance
coarse-grained texture
found in nature

natural science

Minerals are the building blocks of rocks. A rock can be made of one or more minerals.
Minerals and rocks have the following properties:
Property | Mineral | Rock
It is a solid. | Yes | Yes
It is formed in nature. | Yes | Yes
It is not made by organisms. | Yes | Yes
It is a pure substance. | Yes | No
It has a fixed crystal structure. | Yes | No
You can use these properties to tell whether a substance is a mineral, a rock, or neither.
Look closely at the last three properties:
Minerals and rocks are not made by organisms.
Organisms make their own body parts. For example, snails and clams make their shells. Because they are made by organisms, body parts cannot be  minerals or rocks.
Humans are organisms too. So, substances that humans make by hand or in factories are not minerals or rocks.
A mineral is a pure substance, but a rock is not.
A pure substance is made of only one type of matter.  Minerals are pure substances, but rocks are not. Instead, all rocks are mixtures.
A mineral has a fixed crystal structure, but a rock does not.
The crystal structure of a substance tells you how the atoms or molecules in the substance are arranged. Different types of minerals have different crystal structures, but all minerals have a fixed crystal structure. This means that the atoms and molecules in different pieces of the same type of mineral are always arranged the same way.
However, rocks do not have a fixed crystal structure. So, the arrangement of atoms or molecules in different pieces of the same type of rock may be different!

Solution: The properties of granite match the properties of a rock. So, granite is a rock.


Question: What is the capital of West Virginia?

Choices:
- Huntington
- Pierre
- Charleston
- Austin

social science

Identify state capitals of the Southeast

Solution: Charleston is the capital of West Virginia.


Question: Select the organism in the same genus as the pickerel frog.

Choices:
- Lithobates catesbeianus
- Agalychnis callidryas
- Bufo guttatus

This organism is a pickerel frog. Its scientific name is Lithobates palustris.

natural science

Use scientific names to classify organisms

Scientists use scientific names to identify organisms. Scientific names are made of two words.
The first word in an organism's scientific name tells you the organism's genus. A genus is a group of organisms that share many traits.
A genus is made up of one or more species. A species is a group of very similar organisms. The second word in an organism's scientific name tells you its species within its genus.
Together, the two parts of an organism's scientific name identify its species. For example Ursus maritimus and Ursus americanus are two species of bears. They are part of the same genus, Ursus. But they are different species within the genus. Ursus maritimus has the species name maritimus. Ursus americanus has the species name americanus.
Both bears have small round ears and sharp claws. But Ursus maritimus has white fur and Ursus americanus has black fur.

Solution:
A pickerel frog's scientific name is Lithobates palustris. The first word of its scientific name is Lithobates.
Lithobates catesbeianus is in the genus Lithobates. The first word of its scientific name is Lithobates. So, Lithobates catesbeianus and Lithobates palustris are in the same genus.
Agalychnis callidryas is in the genus Agalychnis. The first word of its scientific name is Agalychnis. So, Agalychnis callidryas and Lithobates palustris are not in the same genus.
Bufo guttatus is in the genus Bufo. The first word of its scientific name is Bufo. So, Bufo guttatus and Lithobates palustris are not in the same genus.


Question: What is the capital of Tennessee?

Choices:
- Honolulu
- Nashville
- Little Rock
- Memphis

social science

Identify state capitals of the Southeast

Solution: Nashville is the capital of Tennessee.


Question: Does this passage describe the weather or the climate?

Choices:
- climate
- weather

Figure: Lake Titicaca.
Lake Titicaca is a large, deep lake on the border between Peru and Bolivia. Dry, windy conditions are common each year in June, July, and August.
Hint: Weather is what the atmosphere is like at a certain place and time. Climate is the pattern of weather in a certain place.

natural science

The atmosphere is the layer of air that surrounds Earth. Both weather and climate tell you about the atmosphere.
Weather is what the atmosphere is like at a certain place and time. Weather can change quickly. For example, the temperature outside your house might get higher throughout the day.
Climate is the pattern of weather in a certain place. For example, summer temperatures in New York are usually higher than winter temperatures.

Solution:
Read the passage carefully.
Lake Titicaca is a large, deep lake on the border between Peru and Bolivia. Dry, windy conditions are common each year in June, July, and August.
The underlined part of the passage tells you about the usual wind patterns at Lake Titicaca. This passage does not describe what the weather is like on a particular day. So, this passage describes the climate.


Question: What is the capital of Alabama?

Choices:
- Montgomery
- Birmingham
- Little Rock
- Raleigh

social science

Identify state capitals of the Southeast

Solution: Montgomery is the capital of Alabama.


Question: Which ocean is highlighted?

Choices:
- the Southern Ocean
- the Indian Ocean
- the Atlantic Ocean
- the Pacific Ocean

social science

Oceans are huge bodies of salt water. The world has five oceans. All of the oceans are connected, making one world ocean.

Solution: This is the Pacific Ocean.


Question: What is the capital of Arizona?

Choices:
- Olympia
- Phoenix
- Tucson
- Santa Fe

social science

Solution: Phoenix is the capital of Arizona.


Question: What is the name of the colony shown?

Choices:
- Connecticut
- Georgia
- Indiana
- North Carolina

social science

Solution: The colony is North Carolina.


Question: What is the probability that a fruit fly produced by this cross will have normal wings?

Choices:
- 1/4
- 3/4
- 2/4
- 0/4
- 4/4

This passage describes the wing type trait in fruit flies:
Some scientists breed fruit flies to learn how traits are inherited. These scientists often use flies with vestigial wings, which are shorter and stubbier than normal wings. Fruit flies with vestigial wings cannot fly, so they are easier for scientists to handle and study.
In a group of fruit flies, some individuals have normal wings and others have vestigial wings. In this group, the gene for the wing type trait has two alleles. The allele for vestigial wings (n) is recessive to the allele for normal wings (N).
This Punnett square shows a cross between two fruit flies.

natural science

Use Punnett squares to calculate probabilities of offspring types

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4.


Question: Will these magnets attract or repel each other?

Choices:
- repel
- attract

Two magnets are placed as shown.

Hint: Magnets that attract pull together. Magnets that repel push apart.

natural science

Magnets can pull or push on each other without touching. When magnets attract, they pull together. When magnets repel, they push apart.
Whether a magnet attracts or repels other magnets depends on the positions of its poles, or ends. Every magnet has two poles, called north and south.
Here are some examples of magnets. The north pole of each magnet is marked N, and the south pole is marked S.
If different poles are closest to each other, the magnets attract. The magnets in the pair below attract.
If the same poles are closest to each other, the magnets repel. The magnets in both pairs below repel.

Solution:
Will these magnets attract or repel? To find out, look at which poles are closest to each other.
The south pole of one magnet is closest to the north pole of the other magnet. Poles that are different attract. So, these magnets will attract each other.