(a) what is an ecosystem? (b) Name twi abiotic factors each which affect plants and animals in a terrestrial habitat (c) Describe the effect of three abioti...

(a) What is an ecosystem?

An ecosystem is a natural unit made up of a community of living organisms (the biotic component) interacting with one another and with the non-living (abiotic) part of their environment, together with the exchange of materials and flow of energy between them. Examples include a pond, a forest and a grassland.

(b) Two abiotic factors each affecting plants and animals in a terrestrial habitat

Factors affecting plants: (i) light intensity; (ii) rainfall (water/humidity). Others: temperature, wind, soil nutrients.

Factors affecting animals: (i) temperature; (ii) humidity. Others: light, wind.

(c) Effect of three abiotic factors on a named plant and a named animal

Named plant: maize plant. Named animal: grasshopper (in a grassland habitat).

• Light: Light provides the energy for photosynthesis in the maize plant; without adequate light the maize becomes pale (etiolated) and grows poorly. In the grasshopper, light controls its daily activity, feeding and breeding rhythm.
• Temperature: A suitable temperature speeds up the enzyme reactions of photosynthesis and growth in the maize; very high or very low temperatures reduce growth and may cause wilting or death. Being cold-blooded (poikilothermic), the grasshopper's body temperature and rate of activity rise and fall with the surrounding temperature; extreme cold makes it sluggish and extreme heat can be fatal.
• Water (rainfall/humidity): Water is needed by the maize for photosynthesis, transport of materials and turgidity; shortage of water causes wilting and stunted growth. For the grasshopper, humidity affects water loss from its body; low humidity increases the risk of desiccation, so it seeks moist shelter.