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Connecting a magnesium rod to an underground steel pipeline protects the pipeline from corrosion. because magnesium (e° = −2.37 v) is much more easily oxidized than iron (e° = −0.45 v), the mg rod acts as the anode in a what?
voltaic cell
anode cell
stimulation cell
galvanic cell
Connecting a magnesium rod to an underground steel pipeline protects the pipeline from corrosion. Because magnesium (E° = −2.37 V) is much more easily oxidized than iron (E° = −0.45 V), the Mg rod acts as the anode in a galvanic cell. The pipeline is therefore forced to act as the cathode at which oxygen is reduced. The soil between the anode and the cathode acts as a salt bridge that completes the electrical circuit and maintains electrical neutrality. As Mg(s) is oxidized to Mg2+ at the anode, anions in the soil, such as nitrate, diffuse toward the anode to neutralize the positive charge. Simultaneously, cations in the soil, such as H+ or NH4+, diffuse toward the cathode, where they replenish the protons that are consumed as oxygen is reduced. A similar strategy uses many miles of somewhat less reactive zinc wire to protect the Alaska oil pipeline.
Matrix is the term for the fluid-filled interior of what structure, where most of the cell’s atp is made?
enzyme
nucleus
Golgi apparatus
mitochondria
As the Figure below (a) and (b) shows, a mitochondrion has two phospholipids membranes. The smooth outer membrane separates the mitochondrion from the cytosol. The inner membrane has many folds, called cristae . These cristae greatly increase the membrane surface area for integral proteins. Many proteins involved in cellular respiration are embedded in this inner membrane. The greater surface area allows more proteins to be located there, resulting in more cellular respiration reactions, and more ATP synthesis. ATP is produced by the enzyme ATP synthase, which is a membrane protein of the mitochondria inner membrane. The fluid-filled inside of the mitochondrian, called matrix , is where most of the cell’s ATP is made.
Chitin, also found in the exoskeleton of insects, gives structural strength to the cell walls of fungi. the cell wall protects the cell from what?
starvation and predators
fermentation and predators
entrainment and predators
desiccation and predators
Like plant cells, fungal cells are surrounded by a thick cell wall; however, the rigid layers contain the complex polysaccharides chitin and glucan and not cellulose that is used by plants. Chitin, also found in the exoskeleton of insects, gives structural strength to the cell walls of fungi. The cell wall protects the cell from desiccation and predators. Fungi have plasma membranes similar to other eukaryotes, except that the structure is stabilized by ergosterol, a steroid molecule that functions like the cholesterol found in animal cell membranes. Most members of the kingdom Fungi are nonmotile. Flagella are produced only by the gametes in the primitive division Chytridiomycota. Growth and Reproduction The vegetative body of a fungus is called a thallus and can be unicellular or multicellular. Some fungi are dimorphic because they can go from being unicellular to multicellular depending on environmental conditions. Unicellular fungi are generally referred to as yeasts. Saccharomyces cerevisiae (baker’s yeast) and Candida species (the agents of thrush, a common fungal infection) are examples of unicellular fungi. Most fungi are multicellular organisms. They display two distinct morphological stages: vegetative and reproductive. The vegetative stage is characterized by a tangle of slender thread-like structures called hyphae (singular, hypha), whereas the reproductive stage can be more conspicuous. A mass of hyphae is called a mycelium (Figure 13.22). It can grow on a surface, in soil or decaying material, in a liquid, or even in or on living tissue. Although individual hypha must be observed under a microscope, the mycelium of a fungus can be very large with some species truly being “the fungus humongous. ” The giant Armillaria ostoyae (honey mushroom) is considered the largest organism on Earth, spreading across over 2,000 acres of underground soil in eastern Oregon; it is estimated to be at least 2,400 years old.
What is the term for air moving over earth’s surface?
tidal
humidity
spin cycle
wind
Wind is only air moving over Earth’s surface, but it can cause a lot of erosion. Look at Figure below . It will give you an idea of just how much erosion wind can cause. The dust storm in the photo occurred in Arizona. All that dust in the air was picked up and carried by the wind. The wind may carry the dust for hundreds of kilometers before depositing it.
Each of what paired organs is enclosed within a cavity surrounded by the pleura?
heart
bones
ovaries
lungs
Pleura of the Lungs Each lung is enclosed within a cavity that is surrounded by the pleura. The pleura (plural = pleurae) is a serous membrane that surrounds the lung. The right and left pleurae, which enclose the right and left lungs, respectively, are separated by the mediastinum. The pleurae consist of two layers. The visceral pleura is the layer that is superficial to the lungs, and extends into and lines the lung fissures (Figure 22.14). In contrast, the parietal pleura is the outer layer that connects to the thoracic wall, the mediastinum, and the diaphragm. The visceral and parietal pleurae connect to each other at the hilum. The pleural cavity is the space between the visceral and parietal layers.
What are the best-known extinct vertebrates?
trilobites
snakes
trees
dinosaurs
Introduction Vertebrates are among the most recognizable organisms of the animal kingdom. More than 62,000 vertebrate species have been identified. The vertebrate species now living represent only a small portion of the vertebrates that have existed. The best-known extinct vertebrates are the dinosaurs, a unique group of reptiles, which reached sizes not seen before or after in terrestrial animals. They were the dominant terrestrial animals for 150 million years, until they died out in a mass extinction near the end of the Cretaceous period. Although it is not known with certainty what caused their extinction, a great deal is known about the anatomy of the dinosaurs, given the preservation of skeletal elements in the fossil record. Currently, a number of vertebrate species face extinction primarily due to habitat loss and pollution. According to the International Union for the Conservation of Nature, more than 6,000 vertebrate species are classified as threatened. Amphibians and mammals are the classes with the greatest percentage of threatened species, with 29 percent of all amphibians and 21 percent of all mammals classified as threatened. Attempts are being made around the world to prevent the extinction of threatened species. For example, the Biodiversity Action Plan is an international program, ratified by 188 countries, which is designed to protect species and habitats.
Centrioles help organize the chromosomes before cell division so that each daughter cell has the correct number of what?
receptors
ribosomes
cells
chromosomes
Centrioles are organelles involved in cell division. They help organize the chromosomes before cell division so that each daughter cell has the correct number of chromosomes after the cell divides. Centrioles are found only in animal cells and are located near the nucleus (see Figure above ).
What development is less risky for the mother?
mutation
gastrointestinal
atypical
marsupial
Marsupial development is less risky for the mother. However, the embryo is fragile, so it may be less likely to survive than the fetus of a placental mammal.
What does the term decay in chemistry refer to with regards to atoms?
separation of nuclei
pressures in nuclei
destruction of nuclei
changes in nuclei
You probably associate the term decay with images like the one above. But when it comes to atoms, decay has a different meaning. Decay in chemistry refers to changes in the nuclei of certain atoms.
How does increasing the temperature of reactants affect the rate of their reaction?
it decreases it
it patterns it
it is unchanged
it increases it
When the temperature of reactants is higher, the rate of the reaction is faster. At higher temperatures, particles of reactants have more energy, so they move faster. As a result, they are more likely to bump into one another and to collide with greater force. For example, food spoils because of chemical reactions, and these reactions occur faster at higher temperatures (see the bread on the left in the Figure below ). This is why we store foods in the refrigerator or freezer (like the bread on the right in the Figure below ). The lower temperature slows the rate of spoilage.
What type of eclipse happens when a full moon moves through earth's shadow?
planetary
cycle
solar
lunar
Sometimes a full moon moves through Earth's shadow. This is a lunar eclipse ( Figure below ). During a total lunar eclipse, the Moon travels completely in Earth’s umbra. During a partial lunar eclipse, only a portion of the Moon enters Earth’s umbra. When the Moon passes through Earth’s penumbra, it is a penumbral eclipse. Since Earth’s shadow is large, a lunar eclipse lasts for hours. Anyone with a view of the Moon can see a lunar eclipse.
Dynamite is an example of what type of potential energy?
thermal
carbon
mineral
chemical
Dynamite is another example of chemical potential energy. The major component of dynamite is nitroglycerin, a very unstable material. By mixing it with diatomaceous earth, the stability is increased and it is less likely to explode if it receives a physical shock. When ignited, the nitroglycerin explodes rapidly, releasing large amounts of nitrogen and other gases along with a massive amount of heat.
All the atoms of a given element have the same number what?
neutrons and protons
neutrons and electrons
cells and electrons
protons and electrons
All the atoms of a given element have the same number of protons and electrons, but they may vary in their numbers of neutrons. Atoms of the same element that differ in their numbers of neutrons are called isotopes.
What structures located on chromosomes control characteristics of life and are passed from parents to offspring?
cells
eggs
axons
genes
Characteristics of life are controlled by genes, which are passed from parents to offspring, and are located on chromosomes, like the one shown here, that are found in every cell. The gene theory is one of the unifying principles of biology.
The lattice energy is usually the most important energy factor in determining the stability of what?
saline compound
harmonic compound
magnetic compound
ionic compound
The lattice energy is usually the most important energy factor in determining the stability of an ionic compound.
What kind of organisms helps hold soil in place to slow erosion?
animals
flowers
bacteria
plants
People remove a lot of vegetation. They log forests or prepare the land for farming or construction. Even just walking or riding your bike over the same place can kill the grass. But plants help to hold the soil in place ( Figure below ). Without plants to protect it, soil may be carried away by wind or running water. In many areas, soil is eroding faster than it is forming. In these locations, soil is a non-renewable resource.
Water found on the surface of the earth is referred to as what?
runoff
groundwater
reservoir water
surface water
Which planet is named after the roman goddess of love?
Jupiter
Neptune
Mercury
venus
Named after the Roman goddess of love, Venus is the only planet named after a female. Venus is sometimes called Earth’s “sister planet. ” But just how similar is Venus to Earth? Venus is our nearest neighbor. Venus is most like Earth in size.
In astronomy, what are so dense that not even light can escape their gravity?
red holes
black rods
dwarf stars
black holes
If the core remaining after a supernova is more than about 5 times the mass of the Sun, the core collapses to become a black hole . Black holes are so dense that not even light can escape their gravity. For that reason, we can't see black holes. How can we know something exists if radiation can't escape it? We know a black hole is there by the effect that it has on objects around it. Also, some radiation leaks out around its edges. A black hole isn't a hole at all. It is the tremendously dense core of a supermassive star.
What are the simplest organic compounds?
carbohydrates
proteins
enzymes
hydrocarbons
Summary Covalent inorganic compounds are named by a procedure similar to that used for ionic compounds, using prefixes to indicate the numbers of atoms in the molecular formula. The simplest organic compounds are the hydrocarbons, which containonly carbon and hydrogen. Alkanes contain only carbon–hydrogen and carbon–carbon single bonds, alkenes contain at least one carbon–carbon double bond, and alkynes contain one or more carbon–carbon triple bonds. Hydrocarbons can also be cyclic, with the.
Animals are classified according to morphological and developmental characteristics, such as a body plan. with the exception of sponges, the animal body plan is symmetrical. this means that their distribution of body parts is balanced along this?
ulna
skull
radius
axis
Classification Features of Animals Animals are classified according to morphological and developmental characteristics, such as a body plan. With the exception of sponges, the animal body plan is symmetrical. This means that their distribution of body parts is balanced along an axis. Additional characteristics that contribute to animal classification include the number of tissue layers formed during development, the presence or absence of an internal body cavity, and other features of embryological development.
Competition that occurs between members of the same species, which improves the species’ adaptations, is called what?
adaptive behavior
interspecies competition
commensalism
intraspecific competition
Intraspecific competition occurs between members of the same species. It improves the species’ adaptations.
When we were dealing with electrical effects, it was very useful to speak of an electric field that surrounded what?
sunlight charge
liquid charge
stellar charge
electrical charge
When we were dealing with electrical effects, it was very useful to speak of an electric field that surrounded an electric charge. In the same way, we can imagine a magnetic field surrounding a magnetic pole. The force that one magnet exerts on another can be described as the interaction between one magnet and the magnetic field of the other magnet. Magnetic field lines go from the north magnetic pole to the south magnetic pole. We define the magnetic field at any point as a vector (represented by the letter B ) whose direction is from north to south magnetic poles.
Plants require air, water, nutrients, and what in order to live and survive?
entertainment
money
gravity
light
Exothermic reactions, like all chemical reactions, require what to get started?
specific energy
surface energy
membrane energy
activation energy
All chemical reactions, including exothermic reactions, need activation energy to get started.
What broad group of animals are the first true tetrapods, vertebrates with four limbs?
mammals
fish
reptiles
amphibians
Amphibians are the first true tetrapods , or vertebrates with four limbs. Amphibians have less variation in size than fish, ranging in length from 1 centimeter (2.5 inches) to 1.5 meters (about 5 feet). They generally have moist skin without scales. Their skin contains keratin , a tough, fibrous protein found in the skin, scales, feathers, hair, and nails of tetrapod vertebrates, from amphibians to humans. Some forms of keratin are tougher than others. The form in amphibian skin is not very tough, and it allows gases and water to pass through their skin.
In most fungi, the haploid nuclei contributed by each parent do not do what right away?
vaporize
filter
disperse
fuse
What is telomere shortening associated with?
changing
sleeping
reducing
aging
Telomerase is not active in adult somatic cells. Adult somatic cells that undergo cell division continue to have their telomeres shortened. This essentially means that telomere shortening is associated with aging. In 2010, scientists found [1] that telomerase can reverse some age-related conditions in mice, and this may have potential in regenerative medicine. Mariella Jaskelioff, et al. , “Telomerase reactivation reverses tissue degeneration in aged telomerase-deficient mice,” Nature, 469 (2011):102–7.
What gas is released when dead organisms and other organic materials decompose?
nitrous oxide
hydrogen peroxide
carbon monoxide
carbon dioxide
Carbon dioxide is given off when dead organisms and other organic materials decompose.
What type of lens is thicker at the edges than it is in the middle?
glass lens
convex lens
surface lens
concave lens
A concave lens is thicker at the edges than it is in the middle. This causes rays of light to diverge. The light forms a virtual image that is right-side up and smaller than the object.
A collapsing nebula leads to what process?
chemical reaction
nuclear reaction
destructive fusion
nuclear fusion
Stars form from clouds of gas and dust called nebulas. Nebulas collapse until nuclear fusion starts.
Lenses that focus light are called what?
sensing lenses
active lenses
powering lenses
converging lenses
Lenses , made from curved pieces of glass, focus or de-focus light as it passes through. Lenses that focus light are called converging lenses, and these are the ones used to make telescopes and cameras. Lenses that de-focus light are called diverging lenses.
What happens to the pressure when more gas is added to a rigid container?
Higher
occurs
changes
increases
The acceleration of the car is in the same direction as the velocity.
Often represented by an arrow, a vector is a measurement that has both size and what?
reason
pressure
location
direction
When both distance and direction are considered, motion can be represented by a vector. A vector is a measurement that has both size and direction. It may be represented by an arrow. If you are representing motion with an arrow, the length of the arrow represents distance, and the way the arrow points represents direction. The red arrows on the map in the Figure above are vectors for Jordan’s route from his house to the school and from the school to the post office. If you want to learn more about vectors, watch the video at this URL:.
A solenoid wrapped around a bar of iron or other ferromagnetic material forms what?
compress
impoundment
compass
electromagnet
Solenoids are the basis of electromagnets. An electromagnet is a solenoid wrapped around a bar of iron or other ferromagnetic material (see Figure below ). The electromagnetic field of the solenoid magnetizes the iron bar by aligning its magnetic domains. The combined magnetic force of the magnetized iron bar and the wire coil makes an electromagnet very strong. In fact, electromagnets are the strongest magnets made. Some of them are strong enough to lift a train. The maglev train described earlier, in the lesson "Electricity and Magnetism," contains permanent magnets. Strong electromagnets in the track repel the train magnets, causing the train to levitate above the track.
Enzymes can catalyze up to several million reactions per what?
day
minute
hour
second
Enzymes are extremely efficient in speeding up biochemical reactions. They can catalyze up to several million reactions per second. As a result, the difference in rates of biochemical reactions with and without enzymes may be enormous. A typical biochemical reaction might take hours or even days to occur under normal cellular conditions without an enzyme, but less than a second with the enzyme.
Unipolar, bipolar, multipolar, and pseudounipolar are the four basic types of what?
electrons
ions
protons
neurons
While there are many defined neuron cell subtypes, neurons are broadly divided into four basic types: unipolar, bipolar, multipolar, and pseudounipolar. Figure 35.5 illustrates these four basic neuron types. Unipolar neurons have only one structure that extends away from the soma. These neurons are not found in vertebrates but are found in insects where they stimulate muscles or glands. A bipolar neuron has one axon and one dendrite extending from the soma. An example of a bipolar neuron is a retinal bipolar cell, which receives signals from photoreceptor cells that are sensitive to light and transmits these signals to ganglion cells that carry the signal to the brain. Multipolar neurons are the most common type of neuron. Each multipolar neuron contains one axon and multiple dendrites. Multipolar neurons can be found in the central nervous system (brain and spinal cord). An example of a multipolar neuron is a Purkinje cell in the cerebellum, which has many branching dendrites but only one axon. Pseudounipolar cells share characteristics with both unipolar and bipolar cells. A pseudounipolar cell has a single process that extends from the soma, like a unipolar cell, but this process later branches into two distinct structures, like a bipolar cell. Most sensory neurons are pseudounipolar and have an axon that branches into two extensions: one connected to dendrites that receive sensory information and another that transmits this information to the spinal cord.
How many families are known quarks divided into?
four
two
five
three
The known quarks are divided into three families, low energy, medium energy, and high energy.
The nervous system has two main parts, called the central nervous system and the what?
obsolete nervous system
functional nervious system
useful nervous system
peripheral nervous system
The nervous system has two main parts, called the central nervous system and the peripheral nervous system. The peripheral nervous system is described later in this lesson. The central nervous system is shown in Figure below . It includes the brain and spinal cord.
What makes up the dense outer layer of bones?
plasma
adipose tissue
ligaments
compact bone
Compact bone makes up the dense outer layer of bone. It is very hard and strong.
What type of behaviors are rigid and predictable, and usually involve basic life functions?
impulsive behaviors
diverse behaviors
protective behaviors
innate behaviors
Innate behaviors are rigid and predictable. All members of the species perform the behaviors in the same way. Innate behaviors usually involve basic life functions, such as finding food or caring for offspring. Several examples are shown in Figure below . If an animal were to perform such important behaviors incorrectly, it would be less likely to survive or reproduce.
Yeasts, molds, and mushrooms are all different kinds of what?
fossil
pollen
bacteria
fungi
Yeasts, molds, and mushrooms are all different kinds of fungi. There may be as many as 1.5 million species of fungi ( Figure below ). You can easily see bread mold and mushrooms without a microscope, but most fungi you cannot see. Fungi are either too small to be seen without a microscope, or they live where you cannot see them easily—deep in the soil, under decaying logs, or inside plants or animals. Some fungi even live in, or on top of, other fungi.
What is the term for the preserved remains or traces of organisms that lived in the past?
detritis
corals
bones
fossils
Fossils are the preserved remains or traces of organisms that lived in the past. The soft parts of organisms almost always decompose quickly after death. On occasion, the hard parts—mainly bones, teeth, or shells—remain long enough to mineralize and form fossils. An example of a complete fossil skeleton is shown in Figure below . The fossil record is the record of life that unfolded over four billion years and pieced back together through the analysis of fossils.
What process, which is analogous to mitosis, is a series of events that arrange and separate chromosomes and chromatids into daughter cells?
digestion
apoptosis
inhibition
meiosis
CHAPTER SUMMARY 11.1 The Process of Meiosis Sexual reproduction requires that diploid organisms produce haploid cells that can fuse during fertilization to form diploid offspring. As with mitosis, DNA replication occurs prior to meiosis during the S-phase of the cell cycle. Meiosis is a series of events that arrange and separate chromosomes and chromatids into daughter cells. During the interphases of meiosis, each chromosome is duplicated. In meiosis, there are two rounds of nuclear division resulting in four nuclei and usually four daughter cells, each with half the number of chromosomes as the parent cell. The first separates homologs, and the second—like mitosis—separates chromatids into individual chromosomes. During meiosis, variation in the daughter.
All of the elements in group 9 have nine of which electrons?
gradient
shell
ionic
valence
All of the elements in group 9 have nine valence electrons.
The force of attraction between a positively charged metal ion and the valence electrons it shares with other ions of the metal is called?
temporal bond
ionic bond
metallic yield
metallic bond
A metallic bond is the force of attraction between a positively charged metal ion and the valence electrons it shares with other ions of the metal. The electrons move freely around the positive ions, which form a lattice-like structure.
When a car is brought to a stop by friction on level ground, it loses what?
mass energy
residual energy
exhibit energy
kinetic energy
How Nonconservative Forces Affect Mechanical Energy Mechanical energy may not be conserved when nonconservative forces act. For example, when a car is brought to a stop by friction on level ground, it loses kinetic energy, which is dissipated as thermal energy, reducing its mechanical energy. Figure 7.15 compares the effects of conservative and nonconservative forces. We often choose to understand simpler systems such as that described in Figure 7.15(a) first before studying more complicated systems as in Figure 7.15(b).
What system of the body is responsible for transmitting, processing, and responding to most of the sensory information that is created by various stimuli?
attentive system
respiratory system
circulatory system
nervous system
Animals can detect environmental stimuli, such as light, sound, and touch. Stimuli are detected by sensory nerve cells. The information is transmitted and processed by the nervous system. The nervous system, in turn, may direct the body to respond. Animal Eyes at http://www. surenmanvelyan. com/eyes/animal-eyes/ has 26 images of the eyes of various animals.
Do vascular or nonvascular plants lack tracheids?
both do
vascular
neither do
nonvascular
When the earth is between the moon and the sun, what type of moon shows?
crescent moon
waning moon
half moon
a full moon
A full moon occurs when the whole side facing Earth is lit. This happens when Earth is between the Moon and the Sun. About one week later, the Moon enters the quarter-moon phase. Only half of the Moon’s lit surface is visible from Earth, so it appears as a half circle. When the Moon moves between Earth and the Sun, the side facing Earth is completely dark. This is called the new moon phase. Sometimes you can just barely make out the outline of the new moon in the sky. This is because some sunlight reflects off the Earth and hits the Moon. Before and after the quarter-moon phases are the gibbous and crescent phases. During the crescent moon phase, the Moon is less than half lit. It is seen as only a sliver or crescent shape. During the gibbous moon phase, the Moon is more than half lit. It is not full. The Moon undergoes a complete cycle of phases about every 29.5 days.
The stored chemical energy of trees and other plants is called what?
byproduct energy
decomposition energy
biocomposte energy
biomass energy
The stored chemical energy of trees and other plants is called biomass energy. When plant materials are burned, they produce thermal energy that can be used for heating, cooking, or generating electricity. Biomass—especially wood—is an important energy source in countries where most people can’t afford fossil fuels. Some plants can also be used to make ethanol, a fuel that is added to gasoline. Ethanol produces less pollution than gasoline, but large areas of land are needed to grow the plants needed to make it.
What is the star nearest the earth named?
alpha centauri
apollinaris centauri
andromeda centauri
proxima centauri
Astronomers are used to really big numbers. While the moon is only 406,697 km from earth at its maximum distance, the sun is much further away (150 million km). Proxima Centauri, the star nearest the earth, is 39, 900, 000, 000, 000 km away and we have just started on long distances. On the other end of the scale, some biologists deal with very small numbers: a typical fungus could be as small as 30 μmeters (0.000030 meters) in length and a virus might only be 0.03 μmeters (0.00000003 meters) long.
What are the majority of solution properties dependent upon?
acid state of solute
similar state of solute
gas state of solute
chemical state of solute
The properties of a solution are different from those of either the pure solute(s) or solvent. Many solution properties are dependent upon the chemical identity of the solute. Compared to pure water, a solution of hydrogen chloride is more acidic, a solution of ammonia is more basic, a solution of sodium chloride is more dense, and a solution of sucrose is more viscous. There are a few solution properties, however, that depend only upon the total concentration of solute species, regardless of their identities. These colligative properties include vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure. This small set of properties is of central importance to many natural phenomena and technological applications, as will be described in this module.
What must be combined with a halogen to give it a positive oxidation number?
carbon
nitrogen
calcium
oxygen
Halogens (Cl, Br, I) have negative oxidation numbers when they form halide compounds. When combined with oxygen, they have positive numbers. In the chlorate ion (ClO 3 - ), the oxidation number of Cl +5, and the oxidation number of O is -2.
Hormones are often regulated through what?
intensity loops
alternating loops
response loops
feedback loops
Surging hormones will cause adolescents to have what?
bulging muscles
blackouts
growth spurts
mood swings
Adolescents may have mood swings because of surging hormones .
What is the term for the force that a magnet exerts on certain materials?
potential force
positive force
gravitational force
magnetic force
The force that a magnet exerts on certain materials is called magnetic force . Like electric force, magnetic force is exerted over a distance and includes forces of attraction and repulsion. North and south poles of two magnets attract each other, while two north poles or two south poles repel each other.
What cells does the skeletal system make?
brain cells
Osteoclast
Dendritic cells
blood cells
The skeletal system makes blood cells. Most blood cells are produced inside certain types of bones.
When a stream or river slows down, it starts dropping its what?
pollutants
fragments
organisms
sediments
When a stream or river slows down, it starts dropping its sediments. Larger sediments are dropped in steep areas, but smaller sediments can still be carried. Smaller sediments are dropped as the slope becomes less steep.
What process, which is in many ways the opposite of photosynthesis, shows the interdependence of producers and consumers?
osmosis
primarily respiration
decomposition
cellular respiration
Cellular respiration, in many ways the opposite of photosynthesis, shows the interdependence of producers and consumers. Combined, the two equations demonstrate how energy flows and the carbon and oxygen cycle between organisms and environment.
Which membranous organelles in a cell sequence enzyme and electron molecules for efficient cellular respiration?
bacterial
glucose
protons
mitochondria
Mitochondria, shown here as the green ovals in this animal cell, are membranous organelles which sequence enzyme and electron carrier molecules to make cellular respiration highly efficient. Mitochondria have both an inner and outer membrane, with a matrix inside the inner membrane. The inner membrane has many internal folds, increasing the surface area for proteins and molecules involved in cellular respiration.
In a plant, the flower contains what?
bud and stem
bees and blossoms
seed and leaves
pollen and eggs
What forms when one substances dissolves in another?
complex
a transition
concentrate
a solution
A solution forms when one substance dissolves in another. The substance that dissolves is called the solute. The substance that dissolves it is called the solvent.
What are thought to have evolved at least 200 million years ago from gymnosperms like gnetae?
deciduous trees
yeasts
cone-bearing plants
flowering plants
Flowering plants are thought to have evolved at least 200 million years ago from gymnosperms like Gnetae. The earliest known fossils of flowering plants are about 125 million years old. The fossil flowers have male and female reproductive organs but no petals or sepals.
The chemical and/or physical agents that cause mutations are called what?
genes
dioxins
organelles
mutagens
mutation. The chemical and/or physical agents that cause mutations are called mutagens. Diseases that occur due to mutations in critical DNA sequences are referred to as genetic diseases. Viruses are infectious agents composed of a tightly packed central core of nucleic acids enclosed by a protective shell of proteins. Viruses contain either DNA or RNA as their genetic material but not both. Some RNA viruses, calledretroviruses, synthesize DNA in the host cell from their RNA genome. The human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS).
What is the force that opposes motion between two surfaces that are touching?
gravity
tension
vibration
friction
Friction is a force that opposes motion between two surfaces that are touching. Friction occurs because no surface is perfectly smooth. Friction is greater when objects have rougher surfaces or are heavier so they press together with greater force.
Skeletal, cardiac, and smooth are all types of what?
Connective
Nervous
Epithelial
muscle
There are three different types of muscle tissue in the human body: cardiac, smooth, and skeletal muscle tissues. All three types consist mainly of muscle fibers, but the fibers have different arrangements. You can see how each type of muscle tissue looks in Figure below .
The speed of a wave through connected harmonic oscillators depends on the distance between them, the spring constant, and the what?
temperature
density
concentrations
mass
Most wave media act like a series of connected oscillators. For instance, a rope can be thought of as a large number of masses (molecules) connected by springs (intermolecular forces). The speed of a wave through connected harmonic oscillators depends on the distance between them, the spring constant, and the mass. In this way, we can model wave media using the principles of simple harmonic motion.
Traits may also be controlled by multiple alleles or multiple what?
eggs
chromosomes
lesions
genes
Inheritance is more complex for traits in which there is codominance or incomplete dominance. Traits may also be controlled by multiple alleles or multiple genes. Many traits are influenced by the environment as well.
How many atoms does water contain?
9
4
6
3
Water, like carbon, has a special role in living things. It is needed by all known forms of life. Water is a simple molecule, containing just three atoms. Nonetheless, water’s structure gives it unique properties that help explain why it is vital to all living organisms.
What is the only light that people can see?
UV light
spectrum light
infrared light
visible light
Visible light consists of a very narrow range of wavelengths that falls between infrared light and ultraviolet light. It is the only light that people can see. Different wavelengths of visible light appear as different colors.
What is the name of the system that consists of a hierarchy of taxa, from the kingdom to the species?
zoology
Bohr's law
Mendelian system
linnaean system
The Linnaean system is based on similarities in obvious physical traits. It consists of a hierarchy of taxa, from the kingdom to the species.
If the dna from all 46 chromosomes in a human cell nucleus was laid out end to end, it would measure approximately how long?
one meter
three meters
four meters
two meters
Eukaryotic Chromosomal Structure and Compaction If the DNA from all 46 chromosomes in a human cell nucleus was laid out end to end, it would measure approximately two meters; however, its diameter would be only 2 nm. Considering that the size of a typical human cell is about 10 µm (100,000 cells lined up to equal one meter), DNA must be tightly packaged to fit in the cell’s nucleus. At the same time, it must also be readily accessible for the genes to be expressed. During some stages of the cell cycle, the long strands of DNA are condensed into compact chromosomes. There are a number of ways that chromosomes are compacted. In the first level of compaction, short stretches of the DNA double helix wrap around a core of eight histone proteins at regular intervals along the entire length of the chromosome (Figure 10.4). The DNA-histone complex is called chromatin. The beadlike, histone DNA complex is called a nucleosome, and DNA connecting the nucleosomes is called linker DNA. A DNA molecule in this form is about seven times shorter than the double helix without the histones, and the beads are about 10 nm in diameter, in contrast with the 2-nm diameter of a DNA double helix. The next level of compaction occurs as the nucleosomes and the linker DNA between them are coiled into a 30-nm chromatin fiber. This coiling further shortens the chromosome so that it is now about 50 times shorter than the extended form. In the third level of packing, a variety of fibrous proteins is used to pack the chromatin. These fibrous proteins also ensure that each chromosome in a non-dividing cell occupies a particular area of the nucleus that does not overlap with that of any other chromosome (see the top image in Figure 10.3).
What is a mixture of a solute in a solvent called?
transition
link
structure
solution
Imagine you have a cup that has 100ml water, and you add 15g of table sugar to the water. The sugar dissolves and the mixture that is now in the cup is made up of a solute (the sugar) that is dissolved in the solvent (the water). The mixture of a solute in a solvent is called a solution .
Silver is an example of a mineral containing only one kind of what?
chemical
matter
mass
element
All minerals have a definite chemical makeup. A few minerals are made of only one kind of element. Silver is a mineral made only of silver atoms. Diamond and graphite are both made only of the element carbon.
What particles ancient greeks propose that matter consists of ?
ether
ions
molecules
atoms
Summary 2.1 Early Ideas in Atomic Theory The ancient Greeks proposed that matter consists of extremely small particles called atoms. Dalton postulated that each element has a characteristic type of atom that differs in properties from atoms of all other elements, and that atoms of different elements can combine in fixed, small, whole-number ratios to form compounds. Samples of a particular compound all have the same elemental proportions by mass. When two elements form different compounds, a given mass of one element will combine with masses of the other element in a small, whole-number ratio. During any chemical change, atoms are neither created nor destroyed. 2.2 Evolution of Atomic Theory Although no one has actually seen the inside of an atom, experiments have demonstrated much about atomic structure. Thomson’s cathode ray tube showed that atoms contain small, negatively charged particles called electrons. Millikan discovered that there is a fundamental electric charge—the charge of an electron. Rutherford’s gold foil experiment showed that atoms have a small, dense, positively charged nucleus; the positively charged particles within the nucleus are called protons. Chadwick discovered that the nucleus also contains neutral particles called neutrons. Soddy demonstrated that atoms of the same element can differ in mass; these are called isotopes. 2.3 Atomic Structure and Symbolism An atom consists of a small, positively charged nucleus surrounded by electrons. The nucleus contains protons and neutrons; its diameter is about 100,000 times smaller than that of the atom. The mass of one atom is usually expressed in atomic mass units (amu), which is referred to as the atomic mass. An amu is defined as exactly 1 of the mass of 12 a carbon-12 atom and is equal to 1.6605 × 10−24 g. Protons are relatively heavy particles with a charge of 1+ and a mass of 1.0073 amu. Neutrons are relatively heavy particles with no charge and a mass of 1.0087 amu. Electrons are light particles with a charge of 1− and a mass of 0.00055 amu. The number of protons in the nucleus is called the atomic number (Z) and is the property that defines an atom’s elemental identity. The sum of the numbers of protons and neutrons in the nucleus is called the mass number.
Repolarization occurs when the membrane potential begins to move back toward its resting what?
tension
charge
resistance
voltage
As the membrane potential reaches +30 mV, other voltage-gated channels are opening in the membrane. These channels are specific for the potassium ion. A concentration gradient acts on K+, as well. As K+ starts to leave the cell, taking a positive charge with it, the membrane potential begins to move back toward its resting voltage. This is called repolarization, meaning that the membrane voltage moves back toward the -70 mV value of the resting membrane potential. Repolarization returns the membrane potential to the -70 mV value that indicates the resting potential, but it actually overshoots that value. Potassium ions reach equilibrium when the membrane voltage is below -70 mV, so a period of hyperpolarization occurs while the K+ channels are open. Those K+ channels are slightly delayed in closing, accounting for this short overshoot. What has been described here is the action potential, which is presented as a graph of voltage over time in Figure 12.23. It is the electrical signal that nervous tissue generates for communication. The change in the membrane voltage from -70 mV at rest to +30 mV at the end of depolarization is a 100-mV change. That can also be written as a 0.1-V change. To put that value in perspective, think about a battery. An AA battery that you might find in a television remote has a voltage of 1.5 V, or a 9-V battery (the rectangular battery with two posts on one end) is, obviously, 9 V. The change seen in the action potential is one or two orders of magnitude less than the charge in these batteries. In fact, the membrane potential can be described as a battery. A charge is stored across the membrane that can be released under the correct conditions. A battery in your remote has stored a charge that is “released” when you push a button.
Mollusks have a true coelom and a complete what?
tissues system
skeletal system
nerve system
digestive system
Mollusks have a true coelom and complete digestive system. They also have circulatory and excretory systems. They have a heart that pumps blood, and organs that filter out wastes from the blood.
Which organelles, made of protein and ribosomal rna, build cellular proteins in the cytoplasm?
chromosomes
chloroplasts
dna
ribosomes
The nucleus of many cells also contains an organelle called a nucleolus , shown in Figure below . The nucleolus is mainly involved in the assembly of ribosomes. Ribosomes are organelles made of protein and ribosomal RNA (rRNA), and they build cellular proteins in the cytoplasm. The function of the rRNA is to provide a way of decoding the genetic messages within another type of RNA, called mRNA for messenger RNA, into amino acids. After being made in the nucleolus, ribosomes are exported to the cytoplasm where they direct protein synthesis.
What type of matter makes up most of the universe?
gas
carbon
liquid
plasma
Can you guess what this picture shows? The purple and blue "flames" are matter in a particular state. You’re probably familiar with the states of matter most common on Earth — solids, liquids, and gases. But these "flames" are a state of matter called plasma. This plasma ball was made by humans. Plasma also occurs in nature. In fact, plasma makes up most of the matter in the universe.
Most mammals are viviparous, which refers to what reproductive result?
laying eggs
identical twins
spawning
live birth
Most mammals are viviparous. Their young are born live. They are born either as relatively large, well-developed fetuses or as tiny, immature embryos. Mammals that are viviparous are called therian mammals . Only a few mammals lay eggs instead of giving birth to an infant or embryo.
Proteins are polymers of what kind of acids?
acetic
lipids
lactic
amino
Proteins are polymers of amino acids, which act as the monomers.
What is the official name for the study of life?
botany
chemistry
geology
biology
The study of biology is the study of life. Concept Biology Advanced is the CK-12 Foundation's most extensive material describing the study of life. Concept Biology Advanced presents biology as a set of 18 concepts, with each concept centered around a specific category, such as cell biology or plants. Each concept is comprised of a series of lessons, with each lesson focusing on one specific topic. The complete Concept Biology Advanced is comprised of over 550 lessons. This material has been developed to complement the most advanced secondary-level biology course.
What does an invertebrate, like a snail, not have?
a heart
reproductive organs
eyes
backbone
Snails are an example of invertebrates, animals without a backbone.
What is the dinosaur genus that's closest to modern birds?
Rapter
sauropods
diplodocus
deinonychus
Deinonychus is the genus name of an extinct dinosaur that is considered to be one of the closest non-bird relatives of modern birds. It lived about 110 million years ago in what is now North America. Deinonychus was a predatory carnivore with many bird-like features. For example, it had feathers and wings. It also had strong legs with clawed feet, similar to modern raptors. Its respiratory, circulatory, and digestive systems were similar to those of birds as well. The location of fossilized eggs near Deinonychus fossils suggests that it may have brooded its eggs. This would mean that it was endothermic. (Can you explain why?) On the other hand, Deinonychus retained a number of reptile-like traits, such as jaws with teeth and hands with claws at the tips of its wings.
In what type of organisms are daughter cells individuals?
hematopoietic organisms
multicellular organisms
macroscopic organisms
unicellular organisms
6.4 | Prokaryotic Cell Division By the end of this section, you will be able to: • Describe the process of binary fission in prokaryotes • Explain how FtsZ and tubulin proteins are examples of homology Prokaryotes such as bacteria propagate by binary fission. For unicellular organisms, cell division is the only method to produce new individuals. In both prokaryotic and eukaryotic cells, the outcome of cell reproduction is a pair of daughter cells that are genetically identical to the parent cell. In unicellular organisms, daughter cells are individuals. To achieve the outcome of identical daughter cells, some steps are essential. The genomic DNA must be replicated and then allocated into the daughter cells; the cytoplasmic contents must also be divided to give both new cells the machinery to sustain life. In bacterial cells, the genome consists of a single, circular DNA chromosome; therefore, the process of cell division is simplified. Mitosis is unnecessary because there is no nucleus or multiple chromosomes. This type of cell division is called binary fission.
What group was long considered part of the plant kingdom because of obvious similarities; both are immobile, have cell walls, and grow in soil?
bacteria
mosses
coral
fungi
For a long time, scientists considered fungi to be members of the plant kingdom because they have obvious similarities with plants. Both fungi and plants are immobile, have cell walls, and grow in soil. Some fungi, such as lichens, even look like plants (see Figure below ).
What type of waves transmit the energy of an earthquake?
volcanic waves
tectonic waves
sonic waves
seismic waves
An earthquake is sudden ground movement. This movement is caused by the sudden release of the energy stored in rocks. An earthquake happens when so much stress builds up in the rocks that the rocks break. An earthquake’s energy is transmitted by seismic waves. Each year, there are more than 150,000 earthquakes strong enough to be felt by people. An amazing 900,000 are recorded by seismometers.
In our bodies, the chest cavity is a clear example of a system at what?
default
rest
scale
resonance
It is interesting that the widths of the resonance curves shown in Figure 16.27 depend on damping: the less the damping, the narrower the resonance. The message is that if you want a driven oscillator to resonate at a very specific frequency, you need as little damping as possible. Little damping is the case for piano strings and many other musical instruments. Conversely, if you want small-amplitude oscillations, such as in a car’s suspension system, then you want heavy damping. Heavy damping reduces the amplitude, but the tradeoff is that the system responds at more frequencies. These features of driven harmonic oscillators apply to a huge variety of systems. When you tune a radio, for example, you are adjusting its resonant frequency so that it only oscillates to the desired station’s broadcast (driving) frequency. The more selective the radio is in discriminating between stations, the smaller its damping. Magnetic resonance imaging (MRI) is a widely used medical diagnostic tool in which atomic nuclei (mostly hydrogen nuclei) are made to resonate by incoming radio waves (on the order of 100 MHz). A child on a swing is driven by a parent at the swing’s natural frequency to achieve maximum amplitude. In all of these cases, the efficiency of energy transfer from the driving force into the oscillator is best at resonance. Speed bumps and gravel roads prove that even a car’s suspension system is not immune to resonance. In spite of finely engineered shock absorbers, which ordinarily convert mechanical energy to thermal energy almost as fast as it comes in, speed bumps still cause a large-amplitude oscillation. On gravel roads that are corrugated, you may have noticed that if you travel at the “wrong” speed, the bumps are very noticeable whereas at other speeds you may hardly feel the bumps at all. Figure 16.28 shows a photograph of a famous example (the Tacoma Narrows Bridge) of the destructive effects of a driven harmonic oscillation. The Millennium Bridge in London was closed for a short period of time for the same reason while inspections were carried out. In our bodies, the chest cavity is a clear example of a system at resonance. The diaphragm and chest wall drive the oscillations of the chest cavity which result in the lungs inflating and deflating. The system is critically damped and the muscular diaphragm oscillates at the resonant value for the system, making it highly efficient.
How do prokaryotic cells divide?
multiple fission
Fusion
function fission
binary fission
Prokaryotic cells grow to a certain size. Then they divide by binary fission. This is a type of asexual reproduction. It produces genetically identical offspring. Genetic transfer increases genetic variation in prokaryotes.
What is the term for a series of biochemical reactions by which an organism converts a given reactant to a specific end product?
hydrogen pathway
internal pathway
direct pathway
metabolic pathway
A metabolic pathway is a series of biochemical reactions by which an organism converts a given reactant to a specific end product. As you will learn in Section 20.5 "Stage II of Carbohydrate Catabolism" through Section 20.7 "Stage II of Protein Catabolism", there are specific metabolic pathways—which are different for carbohydrates, triglycerides, and proteins—that break down the products of stage I of catabolism (monosaccharides, fatty acids, and amino acids) to produce a common end product, acetyl-coenzyme A (acetyl-CoA) in stage II of catabolism. Acetyl-CoA is shown in Figure 20.10 "The Structure of Acetyl-Coenzyme A (AcetylCoA)". The acetyl unit, derived (as we will see) from the breakdown of carbohydrates, lipids, and proteins, is attached to coenzyme A, making the acetyl unit more reactive. Acetyl-CoA is used in a myriad of biochemical pathways. For example, it may be used as the starting material for the biosynthesis of lipids (such as triglycerides, phospholipids, or cholesterol and other steroids). Most importantly for energy generation, it may enter the citric acid cycle and be oxidized to produce energy, if energy is needed and oxygen is available. The various fates or uses of acetyl-CoA are summarized in Figure 20.11 "Cell Chemistry". Figure 20.10 The Structure of Acetyl-Coenzyme A (Acetyl-CoA).
Exemplified by sea stars and sand dollars, echinoderms have a calcareous structure developed by pigment cells and made of ossicles, which is called what?
thorax
hydrostatic skeleton
exoskeleton
endoskeleton
Phylum Echinodermata Echinodermata are so named owing to their spiny skin (from the Greek “echinos” meaning “spiny” and “dermos” meaning “skin”), and this phylum is a collection of about 7,000 described living species. Echinodermata are exclusively marine organisms. Sea stars (Figure 28.44), sea cucumbers, sea urchins, sand dollars, and brittle stars are all examples of echinoderms. To date, no freshwater or terrestrial echinoderms are known. Morphology and Anatomy Adult echinoderms exhibit pentaradial symmetry and have a calcareous endoskeleton made of ossicles, although the early larval stages of all echinoderms have bilateral symmetry. The endoskeleton is developed by epidermal cells and may possess pigment cells, giving vivid colors to these animals, as well as cells laden with toxins. Gonads are present in each arm. In echinoderms like sea stars, every arm bears two rows of tube feet on the oral side. These tube feet help in attachment to the substratum. These animals possess a true coelom that is modified into a unique circulatory system called a water vascular system. An interesting feature of these animals is their power to regenerate, even when over 75 percent of their body mass is lost.
What phase does the nuclear envelope begin to break down?
interphase
nitrogenase i
pasiphaë i
prophase i
Prophase I: The nuclear envelope begins to break down, and the chromosomes condense. Centrioles start moving to opposite poles of the cell, and a spindle begins to form. Importantly, homologous chromosomes pair up, which is unique to prophase I. In prophase of mitosis and meiosis II, homologous chromosomes do not form pairs in this way. During prophase I, crossing-over occurs (see below).
What are formed when cells from the male and female parts of the plant combine?
atoms.
varieties
trees
seeds
What is another name for anther pollen sacs?
Gametangia
ganglia
Megasporangia
microsporangia
What is released to lubricate the vagina to facilitate intercourse?
semen
urine
blood
vaginal secretions
The vagina is a muscular tube that serves several purposes. It allows menstrual flow to leave the body. It is the receptacle for the penis during intercourse and the vessel for the delivery of offspring. It is lined by stratified squamous epithelial cells to protect the underlying tissue. Sexual Response during Intercourse The sexual response in humans is both psychological and physiological. Both sexes experience sexual arousal through psychological and physical stimulation. There are four phases of the sexual response. During phase one, called excitement, vasodilation leads to vasocongestion in erectile tissues in both men and women. The nipples, clitoris, labia, and penis engorge with blood and become enlarged. Vaginal secretions are released to lubricate the vagina to facilitate intercourse. During the second phase, called the plateau, stimulation continues, the outer third of the vaginal wall enlarges with blood, and breathing and heart rate increase. During phase three, or orgasm, rhythmic, involuntary contractions of muscles occur in both sexes. In the male, the reproductive accessory glands and tubules constrict placing semen in the urethra, then the urethra contracts expelling the semen through the penis. In women, the uterus and vaginal muscles contract in waves that may last slightly less than a second each. During phase four, or resolution, the processes described in the first three phases reverse themselves and return to their normal state. Men experience a refractory period in which they cannot maintain an erection or ejaculate for a period of time ranging from minutes to hours.
Cnidarians are an example of organisms that possess a simple type of what system, used for sensing touch?
bacterial system
circulatory system
lymphatic system
nervous system
Cnidarians have a simple nervous system. It consists of a net of nerves that can sense touch. You can see a sketch of the nerve net in a hydra in Figure below . Some cnidarians also have other sensory structures. For example, jellyfish have light-sensing structures and gravity-sensing structures.
What can we learn about a wave by finding the product of the wavelength and frequency?
type
decibels
volume
speed
The speed of a wave is a product of its wavelength and frequency. Because all electromagnetic waves travel at the same speed through space, a wave with a shorter wavelength must have a higher frequency, and vice versa. This relationship is represented by the equation:.
Where are liverworts most often found?
in deserts
in the ocean
on mountains
along stream beds
Liverworts have two distinct appearances: they can either be leafy like mosses or flattened and ribbon-like. Liverworts get their name from the type with the flattened bodies, which can resemble a liver ( Figure below ). Liverworts can often be found along stream beds.
What does a continuous string of earthquakes indicate about a volcano?
it is heating up
extinction is close
it is cooling down
eruption is close
Earthquakes may take place every day near a volcano. But before an eruption, the number and size of earthquakes increases. This is the result of magma pushing upward into the magma chamber. This motion causes stresses on neighboring rock to build up. Eventually the ground shakes. A continuous string of earthquakes may indicate that a volcano is about to erupt. Scientists use seismographs to record the length and strength of each earthquake.