Explanation

(a)(i) Components of an ecosystem are:

(1) Producers.

(2) Consumers.

(3) Decomposers.

(ii) The producers or green plants use carbon (iv) oxide, water, chlorophyll and sunlight as a source of energy to produce carbohydrate. The consumers or animals feed on the producers or their products. Consumers release carbon (iv) oxide to the plants to take in. Decomposers or micro-organisms break down dead plants and other organisms to release nutrients which are absorbed by plants

(b) Steps for studying plants and animals in a community:

(i) Mapping out or selection or demarcating of a particular area (ii) Measurement of ecological factors.

(iii) Collection of specimens.

(c)(i) competition: Inadequate supply of nutrients, light, water and food leads to competition which results in survival of the fittest. This means that those that cannot stand the test of competition die. This eventually leads to reduction in population. Lack of these necessities also leads to migration which reduces population size.

(ii) pathogens: These are disease causing agents or organisms which kill other organisms in a population thereby reducing the population. Attack by pathogen can result in the development of resistant strains which eventually lead to a growth of disease free population.

(iii) Water: All living organisms need water for survival.

(1) Water is needed for metabolism.

(2) Lack of water leads to food scarcity and death, thereby reducing population.

(3) Adequate supply of water leads to increase in food production and supply which eventually leads to increase in population.

(4) Excess water supply may result in flooding which brings about displacement and reduction in population.