Passage: 'Photosynthetic efficiency in C3 plants drops noticeably under drought conditions because leaf stomata constrict to conserve moisture. Consequently, internal carbon dioxide concentrations plunge, increasing the frequency of photorespiration catalyzed by the enzyme RuBisCO.'
Why does photorespiration increase when stomata close?
Answer and explanation
Correct answer: A. Internal CO2 drops while oxygen competes at the RuBisCO active site
- Step 1: Review the physiological cascade triggered by stomatal closure in C3 plants described in the text.
- Step 2: When stomata constrict, "internal carbon dioxide concentrations plunge," allowing molecular oxygen () to competitively bind to the active site of RuBisCO in place of , thereby accelerating wasteful photorespiration.
Answer
Internal CO2 drops while oxygen competes at the RuBisCO active site.
Practise more Multiple Choice: Academic Reading Comprehension.
Free questions with an explanation for every one, and full timed PTE Academic mock tests.
More Multiple Choice: Academic Reading Comprehension questions
- Passage: 'Glacial retreat in high-mountain ecosystems disrupts seasonal hydrological cycles. Because snowpack and glacial ice act as natural…
- Passage: 'Behavioral economists have repeatedly demonstrated that loss aversion exerts a stronger psychological pull than equivalent gains.…
- Passage: 'The decipherment of the Linear B script by Michael Ventris in 1952 proved that Mycenaean Greek was an archaic dialect of Hellenic…
- Passage: 'Antimicrobial stewardship programs in hospital environments aim to restrict the overuse of broad-spectrum antibiotics. By conducti…
- Passage: 'The concept of epistemic humility requires researchers to acknowledge the provisional nature of scientific models. Rather than ass…
- Passage: 'Tectonic subduction zones generate the planet's deepest ocean trenches and most explosive volcanic arcs. As the denser oceanic lit…