JAMB Biology 2011 Past Questions & Answers

The bright red head of the male Agama lizard is a secondary sexual characteristic that appears during the breeding season. This vibrant colour serves as a courtship display to attract female lizards. Therefore, its main function is for mating purposes.

Common mistake: Students often mistake this courtship display for a territorial one (Option A), as bright colours in male animals are also frequently used to intimidate and scare off rival males.

Biomass refers to the total mass or weight of a living organism. The question asks which individual organism has the smallest weight. Agama (lizard), Bufo (toad), and Tilapia (fish) are all animals that are much larger and heavier than Spirogyra, which is a simple, thread-like alga. Therefore, a single individual of Spirogyra has the smallest biomass among the given options.

Common mistake: A common mistake is choosing Bufo sp or Tilapia sp by thinking of a small tadpole or baby fish, but an individual Spirogyra filament is microscopic and has a much smaller mass.

Seed-producing plants, also known as Spermatophytes, are a major group in the plant kingdom. They are divided into two main classes: gymnosperms and angiosperms. Gymnosperms are plants that have 'naked' seeds, meaning their seeds are not enclosed in an ovary or fruit, like in pine trees. Angiosperms are flowering plants, and their seeds are protected inside a fruit.

Common mistake: Students often mistakenly choose option B because monocotyledons and dicotyledons are major plant groups, but they are actually the two classes within angiosperms, not the primary division of all seed plants.

Parental care is the protection and nourishment a parent provides to its young ones. Mammals (class Mammalia) exhibit the highest level of parental care among all vertebrates. This is because they feed their young with milk produced by mammary glands, a unique feature that ensures the baby is well-fed and protected for a long period after birth.

Common mistake: Students often mistakenly choose Aves (birds) because birds also show excellent parental care, such as building nests and feeding their chicks, but the care in mammals is considered more advanced due to lactation (feeding with milk).

The question refers to the life cycle of a mosquito, where stage III is the pupa. The adult form of the pupa is the adult mosquito. The adult mosquito is a vector, an organism that transmits disease-causing agents. The Culex mosquito, in particular, transmits the filarial worm that causes elephantiasis, a disease that leads to severe swelling in the limbs and other body parts.

Common mistake: Students may mistakenly choose sleeping sickness because they remember it is a disease transmitted by an insect vector, but they confuse the mosquito with the actual vector, which is the tsetse fly.

The nuptial flight is the mating flight of winged termites, also known as alates. The primary adaptive reason for this behaviour is to disperse from the parent colony to reduce overcrowding and competition. After mating during the flight, the new king and queen find a suitable location to establish a new colony, ensuring the spread and survival of the species.

Common mistake: Students may mistakenly choose option B, as cross-breeding does occur, but the main adaptive importance is the dispersal to establish new colonies, which is a more complete and fundamental reason for the behaviour.

A hypertonic solution is more concentrated with solutes, like salt or sugar, than the inside of a living cell. Because of a process called osmosis, water naturally moves from an area of high water concentration (inside the cell) to an area of low water concentration (the surrounding solution). This movement of water out of the cell causes it to lose water and shrink.

Common mistake: Students often confuse hypertonic with hypotonic, forgetting that 'hypo' means less concentrated, which would cause the cell to swell with water, not shrink.

Leucocytes, also known as white blood cells, are a key part of the body's immune system found in the blood. Unlike red blood cells which lose their nucleus when mature, leucocytes retain their nucleus and are generally larger. This structure is related to their function of defending the body against diseases.

Common mistake: Students often mistakenly choose option C, confusing the role of leucocytes in fighting infection with the role of platelets (thrombocytes) in blood clotting.

The correct answer is assimilation. After food is digested into simple nutrients and absorbed into the blood, assimilation is the final process where the body's cells take up these nutrients and convert them into complex molecules needed for growth and repair. For example, cells use amino acids to build proteins, which become part of the body's tissues.

Common mistake: Students often confuse assimilation with digestion (D), but digestion is the breakdown of large food into small molecules, while assimilation is the process of using those small molecules to build parts of the body.

Irritability, also known as sensitivity, is the correct term for the ability of living things to detect changes (stimuli) in their internal or external environment and react appropriately. This is one of the fundamental characteristics of all living organisms. For example, when you touch a hot object, the stimulus is the heat, and pulling your hand away is the response, which demonstrates irritability.

Common mistake: Students might mistakenly choose 'taxis' because it also involves responding to a stimulus, but taxis specifically refers to a directional movement of an entire organism, which is just one type of response, not the general ability itself.