Question 1

Which of the following best describes photorespiration in plants?

Accepted Answer

When the plant fixes an oxygen to RuBP

Question 2

Why do C4 plants have an advantage over C3 plants in hot, dry environments?

Accepted Answer

C4 plants use PEP carboxylase, which has a higher affinity for CO$$_2$$ and is not affected by O$$_2$$, reducing photorespiration

Question 3

Which enzyme is responsible for the initial fixation of CO$$_2 in C4 $$photosynthesis?

Accepted Answer

PEP carboxylase

Question 4

In C4 plants, what is the first stable product formed after CO$$_2$$ fixation?

Accepted Answer

Oxaloacetate (OAA), a 4-carbon compound

Question 5

Which of the following best explains why C4 photosynthesis is not found in arctic or boreal environments?

Accepted Answer

PEP carboxylase does not function efficiently at low temperatures

Question 6

Which of the following is a key anatomical feature of C4 plants that helps reduce photorespiration?

Accepted Answer

Kranz anatomy, where bundle sheath cells surround vascular bundles and contain Rubisco

Question 7

A C3 plant is grown under the following conditions: 30% O$$_2$$, 200 ppm CO$$_2. $$What is the expected effect on photorespiration?

Accepted Answer

Photorespiration will be maximized

Question 8

Which of the following equations represents the initial carboxylation reaction catalyzed by PEP carboxylase in C4 plants?

Accepted Answer

$$\mathrm{CO_2 + PEP \rightarrow OAA}$$

Question 9

Why do C3 plants lose more energy to photorespiration under normal atmospheric conditions?

Accepted Answer

Rubisco can bind O$$_2 as $$well as CO$$_2$$, leading to energy loss when O$$_2 is $$fixed

Question 10

Which of the following best describes the energy trade-off in C4 photosynthesis compared to C3 photosynthesis?

Accepted Answer

C4 photosynthesis requires more ATP due to the CO$$_2$$ shuttling mechanism

Question 11

A plant species is found to dominate in a moist, tropical environment. Which photosynthetic pathway is it most likely to use, and why?

Accepted Answer

C3, because the energy cost of C4 is not justified in moist, high CO$$_2$$ environments

Question 12

Which of the following is NOT a function of the waxy cuticle on plant leaves?

Accepted Answer

Facilitates the absorption of CO$$_2$$ directly through the cuticle

Question 13

In C4 plants, what happens to pyruvate after CO$$_2 is $$released in the bundle sheath cells?

Accepted Answer

It is converted back to PEP in the mesophyll cells, using ATP

Question 14

Which of the following best explains why C4 plants are not more efficient than C3 plants in high CO$$_2$$, moist environments?

Accepted Answer

The CO$$_2$$ shuttling mechanism in C4 plants becomes saturated at lower CO$$_2$$ concentrations

Question 15

A field experiment compares the rates of photosynthesis in C3 and C4 plants at 35$$^\circC $$and 10% relative humidity. Which result is most likely?

Accepted Answer

C4 plants will have higher rates of photosynthesis due to reduced photorespiration

Question 16

Which of the following statements about Rubisco is correct?

Accepted Answer

Rubisco is present in both C3 and C4 plants, but only in the bundle sheath cells of C4 plants

Question 17

Which of the following best describes the function of stomata in plant leaves?

Accepted Answer

They allow for gas exchange, balancing CO$$_2$$ intake with water loss

Question 18

A C3 plant is grown in an environment with 0% O$$_2$$ and 400 ppm CO$$_2. $$What will be the effect on photorespiration?

Accepted Answer

Photorespiration will be eliminated

Question 19

Which of the following crops is a C4 plant and benefits from its photosynthetic pathway in hot, dry climates?

Accepted Answer

Corn (maize)

C4 Photosynthesis and Leaf Adaptations: Structure, Function, and Comparison with C3 Pathway

스터디 가이드 - 연습 문제