ap bio

Based on Figure 1, which of the following statements best describes the epinephrine signaling pathway? (A) It involves the opening and closing of ion channels. (B.) In involves enzymes activating other enzymes (C) It involves changes in the expression of target genes (D) It involves protons moving down a concentration gradient.

(B.) In involves enzymes activating other enzymes

Cortisol is a hormone produced in response to stress, including starvation, in humans. Which of the following is most likely an immediate effect of a starvation-induced increase in cortisol secretion? Increased activation of the immune svstem (B)Increased urine production by the kidneys (C) Increased bone and collagen formation (D) Increased mobilization of fatty acids from fat cells

(D) Increased mobilization of fatty acids from fat cells

cientists investigated the effect of oxygen levels on the net rate of carbon fixation in two types of plants. The plants were grown in either well-watered soil (control) or dry soil and then exposed to either 21% or 1% O2 . The net rate of CO2 fixation for both types of plants was measured. Data are shown in Figure 1 and Figure 2 . Which of the following statements about the rate of CO2 fixation in the two types of plants is supported by the data shown in the figures? *At 21% O2 , plant type 2 has a lower rate of CO2 fixation than plant type 1 does in both types of soil. At 1% O2 , plant type 2 has a higher rate of CO2 fixation than plant type 1 does in the dry soil but not in the control soil. The rate of CO2 fixation is the same in both types of plants in the control soil at both oxygen levels. Plant types 1 and 2 have a statistically different rate of CO2 fixation in both soil types at both oxygen levels.

*At 21% O2 , plant type 2 has a lower rate of CO2 fixation than plant type 1 does in both types of soil.

In an experiment, the efficiency of oxygen exchange across the plasma membrane is being assessed in four artificial red blood cells. The table above lists some properties of those artificial cells. Other conditions being equal, which artificial cell is predicted to be the most efficient in exchanging oxygen with the environment by diffusion? *the cuboidal cell the tetrahedral cell the cylindrical cell

*the cuboidal cell

Based on the data in Table 1, which of the following is the earliest time point at which there is a statistical difference in average pH between the control and treatment groups? A 5 minutes B 15 minutes C 20 minutes D 35 minutes

35 minutes

Which of the following is the most plausible explanation for these findings? a. A cell surface protein on cell 4 signals cell 3 to induce formation of the worm's intestine. The plasma membrane of cell 4 interacts with the plasma membrane of the posterior portion of cell 3, causing invaginations that become microvilli. Cell 3 passes an electrical signal to cell 4, which induces differentiation in cell 4. Cell 4 transfers genetic material to cell 3, which directs the development of intestinal cells.

A cell surface protein on cell 4 signals cell 3 to induce formation of the worm's intestine.

Which of the following best explains how higher concentrations of nitrogen and phosphorus contribute to eutrophication? A An increase in the population of algae results in more nitrogen and phosphorus in the water, causing severe eutrophication. B Both bacteria and algae require nitrogen and phosphorus, so the algae must grow faster to compete with bacteria. C Nitrogen and phosphorus stimulate oxidative phosphorylation, which consumes the available oxygen in the water. D Algae require nitrogen and phosphorus to build macromolecules, so higher concentrations of these nutrients can result in algal blooms.

Algae require nitrogen and phosphorus to build macromolecules, so higher concentrations of these nutrients can result in algal blooms.

Based on Table 1, which of the following best explains the difference in water potential between certain solutions and the grapes? A) NaCl and tap water have a lower water potential because these two solutions caused the grape to gain water. B) Grape soda and NaCl have a lower water potential because these two solutions caused the grape to lose water C) Tap water and grape juice have a lower water potential because these two solutions caused the grape o to lose water D) Grape soda and grape juice have a lower water potential because these two solutions caused the grape to gain water

B) Grape soda and NaCl have a lower water potential because these two solutions caused the grape to lose water

Humans produce sweat as a cooling mechanism to maintain a stable internal temperature. Which of the following best explains how the properties of water contribute to this physiological process? AThe high specific heat capacity of water allows the body to absorb a large amount of excess heat energy. BThe high heat of vaporization of water allows the body to remove excess heat through a phase change of water from liquid to gas. CThe high surface tension of water contributes to the physical process by which water leaves the body. DThe high melting temperature of water allows the body to remove excess heat through a phase change of water from solid to liquid.

BThe high heat of vaporization of water allows the body to remove excess heat through a phase change of water from liquid to gas.

Based on Table 1, which of the following percentages is closest to the solute concentration of the grape? A) 0.0% B) 1.3% C) 5.5% D) 10.1%

C) 5.5%

Which of the following questions about genetic diversity could most appropriately be answered by analysis of the model in Figure 1 ? ADoes crossing-over generate more genetic diversity than the fusion of gametes does? BDoes DNADNA methylation prevent independent assortment during metaphase IIII? CHow does the independent assortment of the two sets of homologous chromosomes increase genetic diversity? DDo daughter cells that are not genetically identical to parent cells produce viable zygotes?

CHow does the independent assortment of the two sets of homologous chromosomes increase genetic diversity?

Which of the following is responsible for the cohesive property of water? AHydrogen bonds between the oxygen atoms of two adjacent water molecules BCovalent bonds between the hydrogen atoms of two adjacent water molecules CHydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule DCovalent bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule EHydrogen bonds between water molecules and other types of molecules

CHydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule

igure 1. The average amount of time spent by a particular type of eukaryotic cell in each phase of the cell cycleBased on Figure 1, what percent of the time required to complete a full cycle do the cells typically spend in interphase? A5% B35% C50% D95%

D95%

Which of the following best explains how higher concentrations of nitrogen and phosphorus contribute to eutrophication? AAn increase in the population of algae results in more nitrogen and phosphorus in the water, causing severe eutrophication. BBoth bacteria and algae require nitrogen and phosphorus, so the algae must grow faster to compete with bacteria. CNitrogen and phosphorus stimulate oxidative phosphorylation, which consumes the available oxygen in the water. DAlgae require nitrogen and phosphorus to build macromolecules, so higher concentrations of these nutrients can result in algal blooms.

DAlgae require nitrogen and phosphorus to build macromolecules, so higher concentrations of these nutrients can result in algal blooms.

In flowering plants, plasmodesmata are narrow channels through cell walls that connect the cytoplasms of adjacent cells. An explanation of how plant cells communicate across cell walls will most likely refer to the diffusion through plasmodesmata of which of the following? AMembrane-bound organelles BCondensed, duplicated chromosomes CBranched polysaccharides DSmall, water-soluble molecules

DSmall, water-soluble molecules

Based on your understanding of the ways in which signal transmission mediates cell function, which of the following predictions is most consistent with the information given above? a. In an environment with low fixed nitrogen, treating the Anabaena cells with a calcium-binding compound should prevent heterocyst differentiation. b. A strain that overexpresses the patS gene should develop many more heterocysts in a low fixed nitrogen environment. In an environment with abundant fixed nitrogen, free calcium levels should be high in all cells so that no heterocysts develop d. In environments with abundant fixed nitrogen, loss of the het gene should induce heterocyst development.

In an environment with low fixed nitrogen, treating the Anabaena cells with a calcium-binding compound should prevent heterocyst differentiation.

The sequences for two short fragments of DNA are shown above. Which of the following is one way in which these two segments would differ? *Segment 1 would not code for mRNA because both strands have T, a base not found in RNA. Segment 1 would be more soluble in water than segment 2 because it has more phosphate groups. Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three. Segment 1 must be from a prokaryote because it has predominantly A-T base pairs.

Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three.

Antidiuretic hormone (ADH) is important in maintaining homeostasis in mammals. ADH is released from the hypothalamus in response to high tissue osmolarity. In response to ADH, the collecting duct and distal tubule in the kidney become more permeable to water, which increases water reabsorption into the capillaries. The amount of hormone released is controlled by a negative feedback loop. Based on the model presented, which of the following statements expresses the proper relationship between osmolarity, ADH release, and urine production? a. As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine. b. As tissue osmolarity rises, less ADH is released, causing less water to be excreted as urine. C. As tissue osmolarity rises, more ADH is released, causing more water to be excreted as urine. d. As tissue osmolarity rises, less ADH is released, causing more water to be excreted as urine.

a. As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine.