(a) Explain briefly the following terms: ecosystem; abiotic environment. (b) List three ecological factors each...

BIOLOGY
WAEC 2018

(a) Explainbriefly the following terms:

  1. ecosystem;
  2. abiotic environment.

(b) Listthree ecological factorseach which are specific to:

  1. aquatic habitats;
  2. terrestrial habitats.

(c) Statebriefly the relationship between green grass and a rabbit in a given habitat.

(d) Draw a typical pyramid of energy usingfour feeding levels.

Explanation

(a) (i) Ecosystem:

Is a natural unit consisting/made up of living/biotic/organism and non-living/abiotic elements/factors; interacting to produce a stable system.

(ii) Abiotic environment:

The non-living components of the ecosystem; such as light/pH/water/oxygen/wind/temperature etc.

(b) Ecological factors that are specific to:

(i) Aquatic habitat

Salinity; turbidity; tidal movement; dissolved gases; density; substratum; water current.

(ii) Terrestrial habitat

Humidity; soil; topography; wind; altitude; availability of water.

(c) The relationship between grass and rabbit in a given habitat

  • Grass (green plants) can photosynthesize/ manufacture its food;
  • Rabbit which cannot manufacture its food feeds on grass;
  • During respiratory process, rabbit gives out carbon dioxide as a waste product;
  • Grass makes use of the carbon dioxide to manufacture its food;
  • Grass during photosynthesis gives out oxygen as a by-product which the rabbit uses for respiration;

When a rabbit defecates/ dies, bacteria/fungi cause its decay, which forms manure that is absorbed as soil nutrients by grass.

(d) Pyramid of energy



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