Answer the following question given this paragraph: When current keeps reversing direction, it is called alternating current (AC) . You can see how it works in the two diagrams below. The current that comes from a power plant and supplies electricity to homes and businesses is alternating current. The current changes direction 60 times per second. It happens so quickly that the light bulb doesn't have a chance to stop glowing when the reversals occur. Q: What is it called when currents keep reversing direction? Choices: - circle current - emitting current - stream current - alternating current A:
alternating current
Answer the following question given this paragraph: 16 Gregor Mendel and biological inheritance Charles Darwin1 , for all he contributed to the science of biology, never knew about the mechanism by which living things inherit traits from previous generations, or how new traits arise. As any schoolchild can tell you, this mechanism of interitance has since been found to be DNA2 , or deoxyribonucleic acid. DNA allows for stable inheritance of traits: the code in each strand of DNA is replicated precisely through the pairing of basic units along each strand. The error rate in this replication is amazingly low; not even one base pair in a million matches out of sequence. However, when even one base pair is added to a new strain of DNA in an order differently than in the parent chain, it can be the basis of a mutation. These changes in DNA sequences are the microscopic origin of changes in traits of all studied living things. Even the smallest difference in a strand of DNA can result in a change in traits that can cost the life of the organism. Mutations can produce proteins with a new or altered function. In humans, the example of Sickle cell anemia3 is commonly given as its origin is a difference of only one base pair in a section of DNA that encodes red blood cells. Individual sequences of DNA that encode for specific proteins are called genes and are the units of heredity. Each one has a set nucleotide4 , and together all of the genes (and some sequence of DNA that apparently do not code for any biologically important functions) together make up the entire chromosome5. Q: What mechanism is used by living organisms to pass along genes? Choices: - protein - digestion - chlorophyll - dna A:
dna
Q: Answer the following question given this paragraph: the radicle is also growing and producing the primary root. As it grows downward to form the tap root, lateral roots branch off to all sides, producing the typical dicot tap root system. In monocot seeds (Figure 32.21), the testa and tegmen of the seed coat are fused. As the seed germinates, the primary root emerges, protected by the root-tip covering: the coleorhiza. Next, the primary shoot emerges, protected by the coleoptile: the covering of the shoot tip. Upon exposure to light (i. when the plumule has exited the soil and the protective coleoptile is no longer needed), elongation of the coleoptile ceases and the leaves expand and unfold. At the other end of the embryonic axis, the primary root soon dies, while other, adventitious roots (roots that do not arise from the usual place i. the root) emerge from the base of the stem. This gives the monocot a fibrous root system. Q: What is root that does not arise from a usual place? Choices: - momentous - monomers - hypochlorous - adventitious A:
A: adventitious
Question: Answer the following question given this paragraph: Microevolution is the process by which organisms change in small ways over time. Q: What is the process by which organisms change in small ways over time? Choices: - spontaneous mutation - natural selection - adaptation - microevolution A:
Answer: microevolution
*Question*
Answer the following question given this paragraph: The space shuttleand any other rocket-based systemuses chemical reactions to propel itself into space and maneuver itself when it gets into orbit. The rockets that lift the orbiter are of two different types. The three main engines are powered by reacting liquid hydrogen with liquid oxygen to generate water. Then there are the two solid rocket boosters, which use a solid fuel mixture that contains mainly ammonium perchlorate and powdered aluminum. The chemical reaction between these substances produces aluminum oxide, water, nitrogen gas, and hydrogen chloride. Although the solid rocket boosters each have a significantly lower mass than the liquid oxygen and liquid hydrogen tanks, they provide over 80% of the lift needed to put the shuttle into orbitall because of chemical reactions. Q: What do rocket-based systems use to propel itself into space? Choices: - water reactions - hydrogen reactions - nuclear reactions - chemical reactions A:
**Answer**
chemical reactions
*Question*
Answer the following question given this paragraph: Water Stabilizes Temperature The hydrogen bonds in water allow it to absorb and release heat energy more slowly than many other substances. Temperature is a measure of the motion (kinetic energy) of molecules. As the motion increases, energy is higher and thus temperature is higher. Water absorbs a great deal of energy before its temperature rises. Increased energy disrupts the hydrogen bonds between water molecules. Because these bonds can be created and disrupted rapidly, water absorbs an increase in energy and temperature changes only minimally. This means that water moderates temperature changes within organisms and in their environments. As energy input continues, the balance between hydrogen-bond formation and destruction swings toward the destruction side. More bonds are broken than are formed. This process results in the release of individual water molecules at the surface of the liquid (such as a body of water, the leaves of a plant, or the skin of an organism) in a process called evaporation. Evaporation of sweat, which is 90 percent water, allows for cooling of an organism, because breaking hydrogen bonds requires an input of energy and takes heat away from the body. Conversely, as molecular motion decreases and temperatures drop, less energy is present to break the hydrogen bonds between water molecules. These bonds remain intact and begin to form a rigid, lattice-like structure (e. , ice) (Figure 2.9a). When frozen, ice is less dense than liquid water (the molecules are farther apart). This means that ice floats on the surface of a body of water (Figure 2.9b). In lakes, ponds, and oceans, ice will form on the surface of the water, creating an insulating barrier to protect the animal and plant life beneath from freezing in the water. If this did not happen, plants and animals living in water would freeze in a block of ice and could not move freely, making life in cold temperatures difficult or impossible. Q: Temperature is a measure of the motion (kinetic energy) of what? Choices: - particles - nucleus - electrons - molecules A:
**Answer**
molecules