2024 - JAMB Biology Past Questions and Answers - page 1

The kidneys are primarily responsible for regulating the water balance in the body. They filter blood, reabsorbing essential substances like water while excreting waste products and excess water in the form of urine. The lungs and skin also eliminate water, but the kidneys do so on a larger scale. The intestine absorbs water from the digested food.

Termites are known to adopt swarming as an adaptation to overcome overcrowding in their colonies. When a termite colony becomes overcrowded, winged reproductive individuals (alates) are produced. These alates swarm, leave the original colony, and establish new colonies, thus alleviating the overcrowding.

Bryophytes are considered to be intermediate between higher algae and pteridophytes. Pteridophytes are the first vascular plants.

Trees in the savanna habitat are adapted to survive in an environment with seasonal rainfall and frequent fires.

• Thick, corky bark: Protects the trees from damage caused by fire and helps conserve water during the dry season.
• Large, leathery leaves: More characteristic of rainforest trees to capture sunlight in low-light environments.
• Straight, slender stems with branches near the top: Typical of trees in a denser environment.
• Thin, smooth barks: Not common in the savanna because they offer less protection from fire.

The correct answer is the tracheae.

• Tracheae: A network of air-filled tubes that branch throughout the insect's body, allowing direct gas exchange between tissues and the environment.
• Skin: Some gas exchange occurs, but it's not the primary structure.
• Malpighian tubules: Excretory organs, not involved in gas exchange.
• Flame cells: Found in some invertebrates, involved in osmoregulation and excretion, not gas exchange.

Population density is calculated by dividing the population size by the area.

Population size: 2,310,000
Area: 2,310 km²
Calculation: Population density = Population / Area = 2,310,000 / 2,310 = 1000

Homologous structures are anatomical features that share a common ancestry but have evolved to serve different functions in different organisms. The question describes this perfectly.

Hypogeal germination is a type of seed germination where the cotyledons remain underground.

• Maize: Exhibits hypogeal germination. The hypocotyl does not elongate significantly, and the cotyledons stay below the soil surface.
• Castor oil, groundnut, and orange: Show epigeal germination, where the cotyledons are pushed above the ground.

The described features correspond to a specific phylum of animals:

• Bilateral symmetry: Body can be divided into two mirror-image halves.
• Cylindrical bodies: Tube-shaped or worm-like.
• Double openings: Complete digestive system with mouth and anus.

These features are most characteristic of nematodes (roundworms).

• Nematodes: Have bilateral symmetry, cylindrical bodies, and a complete digestive system.
• Hydra: Exhibit radial symmetry.
• Protozoa & Protists: Single-celled and lack these characteristics.

The diagram likely represents zonation in an aquatic environment.

• Littoral zone: Intertidal area exposed during low tide and submerged during high tide; corresponds to Zone II.
• Supra-tidal zone: Area above high tide mark, not part of intertidal zone.
• Pelagic zone: Open water column.
• Benthic zone: Bottom of the water body.