AP Biology Practice Test 34

Test Information

Question 13 questions

Time 15 minutes

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1. The fluidity of the plasma membrane can vary in response to temperature changes. For bacteria and yeast cells, which of the following would be a viable strategy to maintain homeostasis of the plasma membrane in a temperature-varying environment?

Questions 2-3 refer to the following information.

Questions refer to the following graph that plots the rate of a reaction controlled by a human enzyme as a function of temperature.

2. What best explains the change in the rate of reaction from 10° to 40°C (50° to 104°F)?

3. What best explains the change in the rate of reaction beyond 45°C (106°F)?

Questions 4-5 refer to the following information.

Questions refer to the following figure showing a plasma membrane with two embedded proteins that are involved in the movement of materials across the membrane. Each protein is shown in active and inactive states.

4. The membrane protein II is most likely doing which of the following?

5. The transport of a substance through both protein I and protein II

6. The structure of ATP synthase in the plasma membranes of bacteria is nearly identical to that in the mitochondria and chloroplasts of eukaryotic cells. This similarity best supports which of the following hypotheses?

7. Question below refers to the following diagram of a fragment of a protein. Each amino acid is shown with its R group (side chain) indicated by an R. Amino acids with polar, acidic, or basic side chains are white, while amino acids with nonpolar side chains are shaded.

The arrangement of the shaded amino acids illustrates how

8. Which of the following properties is responsible for holding together the water molecules in a vertical column of water in xylem vessels of a plant?

9. The normal pH of the cytosol is about 7.2. Most enzymes in the lysosome, however, are only active at a pH of 5. This suggests that

10. Question below refers to the following figure that shows portions of a mitochondrion and a chloroplast.

A chemiosmotic gradient is generated in both cellular respiration and photosynthesis. The gradient is generated as electrons pass along an electron transport chain in membranes of mitochondria and chloroplasts. Which of the following correctly describes the origin of these electrons as they enter the electron transport chain and the endpoint when they leave the electron transport chain?

Questions 11-13 refer to the following information.

To investigate the rate of photosynthesis under different environmental conditions, researchers grew two groups of saltbush (Atriplex) plants, one in shade and the other in full sun. Leaves from these plants were then used to determine rates of photosynthesis by measuring CO2 assimilation while the leaves were exposed to various intensities of photosynthetically active radiation (PAR).

11. As demonstrated by light intensities above 800 μmol photons/m2/sec, leaves from the plant grown in the sun reached a higher maximal photosynthetic rate. Which of the following is the best hypothesis that can explain why plants grown in full sunlight reach a higher maximal photosynthetic rate than plants grown in shade?

12. Which of the following is the best hypothesis that can explain the observed differences in CO2 assimilation for leaves grown in shade and sun at light intensities between 100 and 150 μmol photons/m2/sec?

13. At light intensities below 50 μmol photons/m2/sec, which of the following best explains why values of CO2 assimilation are negative?