Given below are two statements:
Statement I: In C3 plants, some O2 binds to RuBisCO, hence CO2 fixat

Q: What is NEET?

NEET is a competitive examination conducted in India. This question is from the 2024 NEET Biology paper.

Q: How can I prepare for NEET Biology?

To prepare for NEET Biology, practice previous year questions (PYQs), understand concepts thoroughly, and solve mock tests regularly. This 2024 question covers Photosynthesis in Higher Plants topic.

Q: What is the difficulty level of this question?

This NEET 2024 Biology question has a easy difficulty level and is marked as an important question and is one of the most repeated questions.

Q: Where can I find more NEET previous year questions?

You can find more NEET previous year questions on AspirantMitraa. Browse by subject, topic, year, and difficulty level to practice effectively.

Question

Given below are two statements:
Statement I: In C3 plants, some O2 binds to RuBisCO, hence CO2 fixation is decreased.
Statement II: In C4 plants, mesophyll cells show very little photorespiration while bundle sheath cells do not show photorespiration.
In the light of the above statements, choose the correct answer from the options given below:
(1) Both Statement I and Statement II are true
(2) Both Statement I and Statement II are false
(3) Statement I is true but Statement II is false
(4) Statement I is false but Statement II is true

Accepted Answer

Correct Answer: C — Statement I is true but Statement II is falseStep-by-step Solution:Statement I: In C3 plants, RuBisCO has an affinity for both CO2 and O2. When O2 concentration is high, O2 competes with CO2 and binds to RuBisCO, leading to photorespiration. This decreases the net CO2 fixation. Hence, Statement I is true.Statement II: In C4 plants, mesophyll cells fix CO2 into oxaloacetate using PEP carboxylase, which has no oxygenase activity. Photorespiration is very low in mesophyll cells. However, bundle sheath cells (where the Calvin cycle occurs) are exposed to high CO2 concentration (due to the C4 pump), which suppresses photorespiration. But the statement says "bundle sheath cells do not show photorespiration" – they can still show some photorespiration if CO2 levels drop, but under normal conditions, photorespiration is negligible. However, the key is that mesophyll cells show very little photorespiration (true), but bundle sheath cells also show very little photorespiration due to the CO2-concentrating mechanism. The statement as written might be considered false because it says "do not show photorespiration" – they show very little, but it's not absolute. According to the answer key, Statement II is false. Thus, I true, II false.Key Concepts: C3 vs C4 photosynthesis, RuBisCO oxygenase activity, photorespiration, CO2-concentrating mechanism in C4 plants.

Master NEET with Our Test Series

More Questions from Photosynthesis in Higher Plants

Frequently Asked Questions

Master NEET with Our Test Series

More Questions from Photosynthesis in Higher Plants

Frequently Asked Questions