Biology 2022 Jamb Examination

Air pollutants originate from activities that release harmful substances into the atmosphere. Industrial chimneys emit gases, vehicle exhausts release nitrogen oxides and carbon monoxide, and aerosols contain chemicals that can pollute the air. Sulphur dioxide is a major contributor to acid rain and is also considered an air pollutant, making option C correct.

A snail's body is bilaterally symmetrical and divided into three main parts: the head, the visceral mass (containing most internal organs), and the muscular foot used for locomotion. Unlike insects, snails do not have thorax and abdomen, hence D is correct.

Spines in porcupine fish are a structural adaptation that helps protect the fish from predators. When threatened, the fish inflates its body and exposes its spines, deterring attacks. Other options may be behavioral or unrelated to direct defense against predators.

Tactic movements are directional movements of organisms in response to external stimuli. Phototaxis is a form of tactic movement where Euglena moves toward light to optimize photosynthesis. Nastic movements, by contrast, are non-directional responses.

During metaphase, chromosomes align at the metaphase plate (equatorial plane) to ensure accurate segregation into daughter cells. Anaphase follows metaphase, where sister chromatids are pulled apart, making B the correct answer.

Insects excrete nitrogenous waste mainly in the form of uric acid, which conserves water, allowing them to survive in dry environments. Unlike mammals that excrete urea in urine, insects' uric acid is semi-solid and efficiently conserves water.

Secondary succession occurs on previously occupied land where the soil is already present. Abandoned farmland will undergo secondary succession because the soil supports pioneer species and other colonizers, unlike primary succession which occurs on bare rock.

The Southern Guinea Savanna lies between the rainforest and the Northern Guinea Savanna and covers areas like Kogi and Kwara. This zone has a mixture of grasses and scattered trees and is transitional between forest and savanna vegetation.

The dark stage (Calvin cycle) of photosynthesis does not require light directly. It uses ATP and NADPH from the light-dependent reactions to fix carbon dioxide into carbohydrates. Processes like photolysis and chlorophyll excitation occur only in the light stage.

Sweat glands excrete water, salts, and nitrogenous wastes such as urea. The other layers of the skin serve structural or protective roles rather than metabolic excretion.