WAEC Past Questions and Answers - Page 3500

17,496.

When large numbers of organisms share limited space and resources, the immediate result is

A.

extinction

B.

emigration

C.

competition

D.

immigration

Correct answer is C

Competition in a territory is as a result of a hassle for the available resources within the territory. For instance, when the water in a river seems to be drying out, the organisms in the water begin to compete for the water.

17,497.

An association between living organisms in which one lives on and feeds at the expense of the other is known as

A.

commensalism

B.

predation

C.

parasitism

D.

mutualism

Correct answer is C

A parasite is an organism that lives on or in a host organism and gets its food at the expense of its host.

17,498.

Xerophytes have the following characteristics aimed at conserving water except

A.

thick cuticle

B.

broad leaf surfaces

C.

sunken stomata

D.

waxy cuticle

Correct answer is B

The xerophytes have reduced leaf size in order to reduce the surface area, thereby reducing the water loss in the plant.

17,499.

In an ecosystem, the least efficient energy transfer link is from the

A.

secondary consumers to decomposers

B.

sun to producers

C.

primary consumers to secondary consumers

D.

producer to primary consumers

Correct answer is A

From the food chain, the energy flows from the producers to the primary consumer to the secondary consumers and about 90% of the energy is lost in the process of this transfer. Hence, the energy level by the time it gets to the secondary consumers. There is less energy transferred to the decomposers.

17,500.

Which of the following instruments is used to determine the turbidity of water?

A.

hygrometer

B.

hydrometer

C.

secchi disc

D.

rain gauge

Correct answer is C

The secchi disc is used to check for the transparency and the turbidity of water.