IB DP Biology- D4.2 Stability and change - IB Style Questions For SL Paper 1A -FA 2025
▶️ Answer/Explanation
Rewilding focuses on restoring natural processes and reintroducing key species that have been lost from ecosystems. The reintroduction of keystone species is a central strategy in rewilding projects to restore ecological balance.
✅ Answer: (C)
▶️ Answer/Explanation
Answer: B
Explanation:
- In the carbon cycle, respiration is the process in which organisms break down organic compounds (such as glucose) and release carbon dioxide (CO₂) into the atmosphere. This occurs in plants, animals, and decomposers.
- In the diagram, Arrow B shows carbon moving from organic compounds in plants to CO₂ in the atmosphere, which directly represents plant respiration.
- Other organisms also respire, but B is the clearest and most direct example shown.
Answer Evaluation:
A. Incorrect – Represents photosynthesis, where plants absorb CO₂.
B. Correct – Represents respiration, releasing CO₂ into the atmosphere.
C. Incorrect – Represents feeding (carbon transfer from plants to animals).
D. Incorrect – Represents decomposition, not respiration, though microbes respire during decay.
▶️ Answer/Explanation
Answer: C. II and III only
Explanation:
- An ecosystem includes both living organisms and the physical environment, where energy flows and nutrients cycle.
- Inorganic nutrients (carbon, nitrogen, phosphorus, etc.) are recycled through processes like decomposition and photosynthesis, allowing them to be reused.
- Chemical energy is stored in carbon compounds such as glucose, produced during photosynthesis. This energy is passed through food chains.
- Biomass does not increase at higher trophic levels; it actually decreases because much of the energy is lost as heat, waste, and through respiration.
Answer Evaluation:
A. Incorrect – I is wrong; biomass decreases as trophic level increases.
B. Incorrect – I is wrong; energy is stored but biomass does not increase.
C. Correct – II and III are accurate processes occurring in ecosystems.
D. Incorrect – Includes I, which is not true.