BECE Photosynthesis and Ecosystems 2 — Questions and Answers
Question 1: Which part of the chloroplast is the primary site of the light-dependent reactions of photosynthesis?
- Stroma
- Thylakoid membrane (Correct answer)
- Outer membrane
- Intermembrane space
Correct answer: Thylakoid membrane
The light-dependent reactions occur on the thylakoid membrane, where chlorophyll pigments absorb sunlight.
Question 2: What gas is released as a byproduct of the light-dependent reactions in photosynthesis?
- Carbon dioxide
- Nitrogen
- Oxygen (Correct answer)
- Hydrogen
Correct answer: Oxygen
Oxygen is released when water molecules are split (photolysis) during the light-dependent reactions.
Question 3: In a food chain, which organism converts solar energy into chemical energy?
- Herbivore
- Carnivore
- Producer (Correct answer)
- Decomposer
Correct answer: Producer
Producers (plants and algae) perform photosynthesis, converting solar energy into chemical energy stored in glucose.
Question 4: A hawk eats a snake that ate a frog that ate a grasshopper that ate grass. The hawk is at which trophic level?
- Second
- Third
- Fourth
- Fifth (Correct answer)
Correct answer: Fifth
Grass (1st) → grasshopper (2nd) → frog (3rd) → snake (4th) → hawk (5th trophic level).
Question 5: Which pigment in plants absorbs light energy most efficiently for photosynthesis?
- Xanthophyll
- Carotenoid
- Chlorophyll (Correct answer)
- Anthocyanin
Correct answer: Chlorophyll
Chlorophyll is the primary photosynthetic pigment that absorbs red and blue light most effectively.
Question 6: What is the role of NADPH produced during the light reactions of photosynthesis?
- It splits water molecules
- It carries electrons to the Calvin cycle (Correct answer)
- It pumps protons across the membrane
- It absorbs sunlight directly
Correct answer: It carries electrons to the Calvin cycle
NADPH acts as an electron carrier, transporting high-energy electrons from the light reactions to the Calvin cycle.
Question 7: Which of the following best describes a 'niche' in an ecosystem?
- The physical location where an organism lives
- The total role an organism plays including what it eats and how it interacts (Correct answer)
- The number of organisms in a population
- The geographic range of a species
Correct answer: The total role an organism plays including what it eats and how it interacts
A niche includes an organism's habitat, diet, behavior, and all interactions — it is the organism's functional role in the ecosystem.
BECE Photosynthesis and Ecosystems 2
Which part of the chloroplast is the primary site of the light-dependent reactions of photosynthesis?