JAMB Biology Past Questions & Answers - Page 47

231.

Which of the following scenarios is an example of cohesion?

A.

Water molecules stick to the surface of a mirror.

B.

Water sticks to the walls of blood vessels.

C.

Water molecules stay on the tip of a pine needle because the water is attracted to the surface of the needle.

D.

Water molecules stick to one another and form a bead

Correct answer is D

Cohesion is an ability of water molecule to stick to one another due to the presence of hydrogen bonding.

232.

The level of organization in spirogyra and volvox is

A.

organ

B.

system

C.

cell

D.

Tissue

Correct answer is C

The spirogyra and volvox are cells. The spirogyra is a cell acting as a FILAMENT while in the Volvox, it's a cell as a COLONY.

233.

Size, colour and fingerprints are examples of ______

A.

physiological variation

B.

discontinuous variation

C.

morphological variation

D.

adaptive variation

Correct answer is C

Morphological variation includes aspects of the outward appearance i.e shape, structure, color, pattern, size which is in contrast to physiology variation which deals primarily with function.

Morphological variation arises from a number of factors which can be bluntly classified as either genetic or environmental implanted into the process of evolution.
 

234.

Nitrogen is released into the atmosphere when ________

A.

plants absorbs mineral salt

B.

sugar is completely broken down

C.

through plant uptake

D.

when lightning strike

Correct answer is D

Nitrogen is essential to all living systems, which makes the nitrogen cycle one of Earth's most important nutrient cycles.

Atmospheric nitrogen becomes part of living organisms in two ways. The first is through bacteria in the soil that form nitrates out of nitrogen in the air. The second is through lightning. During electrical storms, large amounts of nitrogen are oxidized and united with water to produce an acid that falls to Earth in rainfall and deposits nitrates in the soil.

235.

The feeding relationship among a set of members of a community is referred to as _______?

A.

a food web

B.

pyramid of energy

C.

a food chain

D.

pyramid of number

Correct answer is C

Feeding relationships between organisms in a community are represented by food chains, which show the sequence in which organisms feed on each other. The chain generally begins with an autotroph such as a green plant (e.g. stinging nettle ---> small tortoiseshell butterfly caterpillar --> house sparrow --> sparrowhawk), or with dead organic matter (detritus) (e.g. leaf litter --> earthworm --> young blackbird --> fox). The arrows indicate the passage of food, and therefore energy flow, from one organism to another.

Pyramids of energy are the most accurate representation of feeding relationships in a community, providing information about the amount of energy flowing through each trophic level over a set period of time.

Food web involve many complex feeding relationship and most most ecosystems are more complex than food chain.