2018 JAMB BIOLOGY PAST QUESTIONS AND ANSWERS

The structure associated with aerobic respiration is typically the mitochondrion, where ATP is generated. Aerobic respiration requires oxygen and occurs in mitochondria. The other options represent different cellular structures unrelated to aerobic respiration.

Structure 5 likely represents an organelle or part involved in a specific function such as secretion or energy production. The correct answer is determined by the relevance of each option to biological processes.

Angiosperms and gymnosperms are seed-producing plants classified as spermatophytes. Angiosperms produce seeds in fruits, while gymnosperms produce exposed seeds. Other options are unrelated plant groups.

Non-green plants, like fungi, lack chlorophyll and cannot photosynthesize. They obtain nutrients by other means, often decomposing organic matter. The other options include green plants.

Sting cells, or cnidocytes, are characteristic of cnidarians like Hydra. These cells help capture prey or defend against threats by delivering toxins. The other options lack sting cells.

Pteridophyta includes plants like ferns, which are differentiated into roots, stems, and leaves. Algae and other lower plants lack these structures or show less differentiation.

Breathing roots have lenticels, which are small openings that enable gas exchange, crucial for plants in waterlogged soils. Stomata are usually found on leaves and serve a similar purpose.

The annulus assists in spore dispersal by creating tension that releases spores when mature, ensuring reproduction. The other options do not apply to the annulus function.

Paramecia are adapted to their environment by having cilia, which aid in movement and feeding. Other options do not offer the same adaptive advantage for their mobility and feeding.

The clitellum in earthworms secretes a mucous cocoon for protecting eggs, crucial for reproduction. Other structures have different functions in the earthworm’s body.

Maxillipeds in crayfish assist in feeding, manipulating food toward the mouth. They are not primarily used for movement or respiration.

Land snails breathe through a mantle cavity, which functions similarly to lungs. Other options do not serve this purpose in snails.

Structure 4 in tadpoles is likely used for respiration as they develop. Other options do not relate to a tadpole’s respiratory needs.

Structure 5 in tadpoles, which is typically the tail, becomes shorter as it metamorphoses into a frog, adapting to its adult environment.

Gill rakers help filter out particles from water, aiding in feeding by protecting delicate gill tissues. They are not involved in respiration or other functions.

A wide pith with conducting tissues characterizes dicot roots like those in beans. Monocots have different internal structures.

Sugar is formed immediately after the first product of photosynthesis (glucose). Other options are synthesized later or stored differently.

Nutrient absorption primarily occurs in the small intestine. Other parts have different functions in digestion.

The pancreas secretes digestive enzymes like trypsin, amylase, and lipase. Other organs do not produce these enzymes.

The liver is an accessory organ that aids in digestion by producing bile. Other organs have different primary roles.

Hydrogen is common in all biomolecules, while nitrogen is unique to proteins. Other options are elements but not common to all three types.

Enamel is the hard outer layer of the tooth crown, providing protection. Other options form different parts of the tooth structure.

Lactic acid forms when oxygen levels are low, causing anaerobic respiration. This is different from the products of aerobic respiration.

Reduced humidity accelerates transpiration by increasing the water vapor gradient between the leaf and surrounding air. Other options slow down transpiration.

The solution level changes due to osmosis, where water moves toward the stronger solution in Y, raising the level in Y while lowering it in X.

Osmosis is the movement of water molecules through a semi-permeable membrane from a region of lower solute concentration (X) to higher solute concentration (Y). This process does not require energy and continues until equilibrium is reached. Other processes like diffusion involve solute particles.

Fibrinogen and prothrombin are essential for blood clotting. Fibrinogen converts to fibrin, forming a clot, while prothrombin is a precursor that activates to initiate the clotting process. Other processes like deamination involve different proteins and functions in the body.

The pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation. Unlike other arteries, it carries blood low in oxygen. The pulmonary vein, on the other hand, carries oxygenated blood back to the heart.

Resin is a plant excretory product often produced in response to injury. It helps to seal wounds and prevent infection. Other options like oils are produced for different purposes or functions in plants, not for excretion.

Taxis is the directed movement of an organism toward or away from a stimulus. For example, phototaxis is movement in response to light. Tropism typically refers to plant movements, while nastic movements are non-directional responses in plants.

The thoracic vertebra in vertebrates has a centrum, which forms part of the spinal column and supports the body. Other vertebra types like the atlas and axis serve different roles in the neck region without a distinct centrum.

The epididymis stores sperm cells and allows them to mature before they are expelled during reproduction. It is a crucial part of the male reproductive system, unlike other structures that have different functions.

An aggregate fruit is formed from multiple carpels of one flower, each producing a small fruit that combines into a single unit. This is different from multiple fruits, which develop from multiple flowers.

In vegetative propagation, new plants grow from parts of the parent plant without genetic exchange. This results in genetically identical offspring, unlike sexual reproduction that involves the mixing of genetic material.

In epigeal germination, the seedling emerges above the soil, as seen in groundnuts. Other plants like maize and sorghum undergo hypogeal germination, where the seedling remains below the soil surface.

Gibberellin is a plant hormone that promotes cell elongation and growth, allowing dwarf plants to reach normal height. Other hormones like thyroxin affect animals, not plant growth.

Gregor Mendel, known as the father of genetics, made groundbreaking discoveries in inheritance patterns through pea plant experiments. Other scientists contributed to biology, but Mendel’s work laid the foundation for genetics.

Crossing-over is the process where homologous chromosomes exchange genetic material during meiosis, creating genetic diversity. Other terms like mutation refer to genetic changes unrelated to meiosis.

In genetic crosses, the dominant trait appears in both F1 and F2 generations when two heterozygotes mate, due to the expression of the dominant allele over the recessive one.

River blindness is not sex-linked, as it is typically caused by infection. Other conditions like color blindness and haemophilia are linked to sex chromosomes, affecting inheritance patterns.