(a)(i) Ecological succession: A gradual and orderly change/replacement; of different species of plant and animal communities, in a given area; over a period of time, until the conditions Of the area became gradually modified by their activities, so that a climax/equilibrium/balanced community is reached/established.
(ii) Process of ecological succession on a bare piece of land: -

The first living organisms on a bare plot of land are the pioneers/algae/mosses
as the pioneers live and die they add nutrients to the soil
this creates conditions that are more suitable/favourable to other plants/ferns/herbs/lower animals/insects/ worms which could not live there before
as they also live and die, their remains improve the soil conditions farther
and so perennial herbs/grasses and other animals/lizards, snakes, toads, rats are able to live there
subsequently a point is reached at which the soil can support the growth of taller / species/shrubs/ trees and higher animals
and higher animals/birds/various mammals may be found at this stage
a climax community is established which is in equilibrium with the environment.

(b)(i) Biosphere: - Parts of the earth/air, water, soil; in which life exists.
(ii) Population: - Total number of organisms; of the same species; which live in a given area; at a given time.
(iii) Community: -A group of different living organisms/ population; living together in a habitat; and interacting with each other.
(iv) Ecosystem: - A natural unit; made up of living organisms and their non-living components; interacting together; to produce a stable system.
(c)(i) Instrument or measuring relative humidity: Hygrometer/wet-dry bulb/paper hygrometer.
(ii) Instrument for measuring wind speed: Anemometer.