photoynthesis

Question 1

Explain why waterlogging reduces photosynthesis.

Answer 1

Roots respire anaerobically → toxin buildup → root death → ↓water/nutrient uptake.

Stomata close (due to root damage) → ↓CO₂ for Calvin cycle.

Chlorosis (Mg²⁺ loss) → ↓chlorophyll → ↓light absorption.

Question 2

Why might waterlogged leaves wilt?

Answer 2

Damaged roots cannot absorb water → leaf dehydration → loss of turgor.

Question 3

Explain why water stress reduces the rate of photosynthesis.

Answer 3

Stomata close to conserve water → limits CO₂ uptake for Calvin cycle.

Less photolysis → fewer electrons for ETC → reduced ATP/NADPH.

RuBisCO activity declines → GP and TP decrease.

Question 4

Why might a plant in dry conditions have lower levels of TP?

Answer 4

Less CO₂ enters due to stomatal closure → less RuBP carboxylation → reduced GP → less TP synthesis.