Theory question 108
Adaptation(For candidates in Nigeria only)
(a) Explain the term adaptation in relation to the mode of life of an organism.
(b) Explain how each of the following structures adapt the organisms that possess them to their modes of life:
(i) succulent leaves in Aloe sp; (ii) succulent stems and reduced leaves in cactus plants; (iii) short, strong beaks in fowls; (iv) counter shading in fish; (v) tiny scale leaves on needle-like branches of pine trees.
(c)(i) What is population? (ii) State five effects of overpopulation on a community.
Show the model answer
(a) Adaptation is the possession of structural, physiological or behavioural features that enable an organism to survive and reproduce in its particular habitat and way of life.
(b)(i) Fleshy leaves store water for use in dry periods.
(ii) Fleshy stem stores water and photosynthesises; leaves reduced to spines cut transpiration and deter grazing animals.
(iii) Short strong beak picks up and cracks grains and seeds and digs for food.
(iv) Dark back and pale belly: seen from above the fish matches the dark water, from below the bright surface, so it is hidden from predators and prey.
(v) Small scale leaves/needles have a small surface area and thick cuticle, reducing water loss in cold or dry conditions.
(c)(i) All the organisms of one species living in a particular area at a given time.
(ii) Any five: shortage of food; competition for space and resources; overcrowding and poor housing; rapid spread of disease; more pollution and waste; unemployment and crime; shortage of water and amenities; destruction of habitats.
For each structure in (b) link the feature to the problem it solves.