Theory question 102
Feeding Relationships and Energy Flow(a) With reference to the food chain, explain the role of the following: (i) green plants (ii) herbivores (iii) carnivores (iv) decomposers.
(b) With the aid of a diagram, describe the carbon cycle.
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(a)(i) Green plants: producers – make food by photosynthesis, trapping the sun's energy; first trophic level; food for all other organisms
(ii) Herbivores: primary consumers – eat plants and pass energy on to carnivores
(iii) Carnivores: secondary/tertiary consumers – feed on herbivores (or other carnivores); help control herbivore numbers
(iv) Decomposers (bacteria, fungi): break down dead bodies and wastes; release nutrients back to the soil/air for producers
(b) Diagram with labelled arrows: CO₂ in air → photosynthesis → plants → eaten by animals; respiration of plants and animals → CO₂; death → decay by decomposers → CO₂; fossil fuels formed from dead remains → burning (combustion) → CO₂; CO₂ dissolves in water bodies; volcanic action adds CO₂
Description: carbon is taken from the air only by photosynthesis and returned by respiration, decay and burning, keeping CO₂ level fairly constant
Label every arrow in the carbon cycle diagram with its process.