Unit 3: Cellular Energetics
Biology · Unit 3 · Paper 1

Cellular Energetics unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1Paper 2Paper 3
Each paper is built from this unit’s 40 terms and is the same for everyone, so a teacher can assign “Unit 3, Paper 1” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.
Suggested time 31 min 28 points0/17 attempted
1

Rubisco and photorespiration

2

Products of the light reactions

3

Glycolysis

4

Allosteric regulation

5

Enzyme mechanism

6

Coupled reactions

7

Calvin cycle

8

Light-dependent reactions

9

Effect of temperature on enzymes

10

Enzyme specificity

11

Pyruvate oxidation

12

Anabolic vs catabolic pathways

Short answer 1. Define or explain: Free energy and ΔG

3 pts

Short answer 2. Define or explain: Photosystems II and I

3 pts

Short answer 3. Define or explain: Chemiosmosis

3 pts

Short answer 4. Define or explain: C4 and CAM plants

3 pts

Free response

4 pts

The enzyme rubisco catalyzes the attachment of CO₂ to RuBP in the Calvin cycle, but it can also bind O₂ instead of CO₂, initiating photorespiration. On hot, dry days when stomata close, the ratio of O₂ to CO₂ inside a leaf rises.

(a) Explain why closing the stomata on a hot, dry day raises the ratio of O₂ to CO₂ inside the leaf.

(b) Explain why photorespiration reduces the efficiency of photosynthesis.

(c) Describe how C4 plants reduce photorespiration.

(d) Predict the type of environment in which C4 plants would have the greatest advantage over C3 plants, and justify your prediction.