The diagram shows a marine food web.
At which trophic levels is the cod found?
A) primary consumer and secondary consumer
B) secondary consumer and tertiary consumer
C) secondary consumer only
D) tertiary consumer only
▶️ Answer/Explanation
Ans: B
In the given marine food web, the cod occupies two trophic levels:
- Secondary consumer: When it eats primary consumers like small fish or crustaceans.
- Tertiary consumer: When it preys on other secondary consumers.
Option B correctly identifies both roles. The cod cannot be a primary consumer (A) as it doesn’t eat producers, and options C/D are incomplete as they ignore one of its trophic levels.
The diagram shows a food chain.
What is the correct pyramid of numbers for this food chain?
▶️ Answer/Explanation
Ans: A
The food chain shown is:
Grass → Grasshopper → Frog → Snake
A pyramid of numbers represents the quantity of organisms at each trophic level:
- Base (Producers): Grass is most numerous.
- Primary Consumers: Fewer grasshoppers than grass plants.
- Secondary Consumers: Even fewer frogs than grasshoppers.
- Tertiary Consumers: Snakes are the least numerous.
This forms a classic upright pyramid (Option A), as energy is lost at each trophic level, supporting fewer organisms.