JAMB Biology 2023 Past Questions & Answers

Malaria is caused by a microorganism called Plasmodium, which is a protozoan. The Anopheles mosquito acts as a vector, transmitting this Plasmodium parasite from an infected person to a healthy one. Therefore, this option describes a microorganism (Plasmodium) being transmitted by a disease vector (mosquito) to cause illness.

Common mistake: Students might choose C (Bacteria causing food poisoning) because bacteria are microorganisms that cause disease, but in this case, the bacteria are the pathogen directly causing the illness, not acting as a vector to transmit another microorganism.

Irritability, also known as sensitivity, is one of the fundamental characteristics of living organisms. It is defined as the ability of an organism or its cells to detect and respond to changes in their internal or external environment. These changes, such as light, temperature, or chemical signals, are called stimuli.

Common mistake: Students may confuse irritability with other life processes, like respiration (generating energy) or growth, because all are essential characteristics of living cells, but only responding to stimuli defines irritability.

The vacuole is a large organelle found inside plant cells that contains cell sap. This organelle is surrounded by a selectively permeable membrane known as the tonoplast. The tonoplast is responsible for controlling the movement of substances into and out of the vacuole, which helps maintain pressure within the cell.

Common mistake: Students may confuse the tonoplast with other organelles ending in '-plast', such as Amyloplast, which is a plastid responsible for storing starch, not the membrane of the vacuole.

The theory of evolution is supported by several pieces of evidence from different fields of biology. Fossils of extinct organisms show how life forms have changed over long periods. Homologous structures, like the forelimbs of different mammals, have a similar underlying plan which suggests a common ancestor. Similarities in the early development of embryos across different species also point to a shared ancestry. Since all these options are correct, the best answer is 'All of the above'.

Common mistake: Students might hastily choose one of the specific examples like fossils (C), forgetting that all the listed options are correct evidences for evolution, making 'All of the above' the most complete answer.

The question asks for an adaptation for survival in social insects. The formation of complex caste systems, where individuals specialize in different roles like reproduction, foraging, or defense, is a unique and highly effective adaptation that ensures the survival and success of social insect colonies. This division of labor allows for efficient resource management and protection against threats.

Common mistake: Students might incorrectly choose options like migration or hibernation because these are general adaptations for survival in some animals, but they are not specific or primary adaptations related to the social structure of insects, unlike the caste system.

The alimentary canal is the continuous tube through which food passes from the mouth to the anus. The oesophagus, large intestine, and small intestine are all direct parts of this tube. The liver is an accessory digestive organ that produces bile and processes nutrients, but food does not pass directly through it, making it not part of the alimentary canal itself.

Common mistake: Students often confuse accessory digestive organs like the liver or pancreas with the alimentary canal because they are crucial for digestion, even though food does not pass through them directly.

Evolution is driven by natural selection, which acts on the variations present within a population. Increased genetic diversity means there is a wider range of traits, which increases the probability that some individuals will be able to survive and reproduce, especially when the environment changes. This makes the population more adaptable and resilient over time.

Common mistake: Students may mistakenly think evolution is always about organisms becoming more complex, getting confused by option A, without realizing that genetic diversity is the essential raw material for natural selection to occur.

Kingdom Plantae is characterized by organisms that are multicellular, eukaryotic, and possess cell walls made of cellulose. A defining feature of plant cells is the presence of chloroplasts, which are organelles containing chlorophyll. These chloroplasts are essential for photosynthesis, allowing plants to produce their own food.

Common mistake: Students often choose 'Ability to perform photosynthesis' (B) because it's a well-known plant function, but the presence of chloroplasts (A) is the specific structural feature that enables this and is a more fundamental defining characteristic of the kingdom, as some other organisms also photosynthesize.

The question describes a biome based on its climatic conditions (hot summer, warm winter) and vegetation type (treeless). This directly relates to ecological factors that define different habitats and how organisms (like plants) are adapted to them. Steppe grasslands are known for these characteristics, being vast treeless plains with distinct seasonal temperatures.

Common mistake: Students might confuse Steppe grasslands with Savannah grasslands, but Savannahs typically have scattered trees and a more pronounced wet and dry season, unlike the treeless nature described.

Physiological variation refers to differences in the functions or processes within an organism's body. Blood pressure is a measure of how the circulatory system is functioning, so differences in blood pressure among individuals is a perfect example of a physiological variation. The other options like beak shape, fur colour, and leaf shape are examples of morphological variation, which deals with differences in physical form and structure.

Common mistake: Students often mistake morphological variation for physiological variation, choosing an option like B (beak shape) because it is a famous example of variation, without realizing it relates to physical structure, not bodily function.

The skeletal system is the framework of the body that provides support, protection, and enables movement. Its main components are bones, which form the rigid structure, and joints, which are the points where bones meet and allow for movement. Therefore, bones and joints are fundamental parts of the human skeletal system.

Common mistake: Students might choose option B (Ligaments and tendons) because they are associated with movement and support, but ligaments connect bones to bones, and tendons connect muscles to bones; they are not the primary structural components of the skeleton itself.

Ecological management and conservation involve protecting natural resources and ecosystems. Establishing marine protected areas is a direct example of this, as it designates specific ocean regions to safeguard marine biodiversity, habitats, and ecological processes. This practice helps maintain the health and sustainability of marine ecosystems by limiting human activities that could cause harm.

Common mistake: Students might be tempted by option A (Construction of a dam) because it involves environmental management, but dams often alter ecosystems rather than conserving them in their natural state, making it an incorrect choice for 'conservation'.

Robert Hooke is the correct answer because in 1665, he was the first person to observe and name cells. While looking at a thin slice of cork under a microscope, he saw tiny, box-like compartments which he called 'cells' because they reminded him of the small rooms in a monastery.

Common mistake: Students might mistakenly choose Schwann because he was a key figure in developing the cell theory, but it was Robert Hooke who first observed and named the cell.

The lungs are the primary organs for respiration because they contain millions of tiny air sacs called alveoli. It is across the thin walls of these alveoli that the actual exchange of gases—oxygen entering the blood and carbon dioxide leaving it—takes place. The other parts like the trachea and bronchi are simply passages for air to travel to the lungs, not the site of exchange.

Common mistake: Students might mistakenly choose the diaphragm because it is the main muscle that powers the mechanics of breathing, but it does not perform the actual gas exchange itself.

The question directly tests knowledge about the endocrine system, specifically which gland produces a particular hormone. The pancreas is an endocrine gland that produces insulin, a hormone vital for regulating blood sugar levels. This falls under hormonal coordination, which is how the body uses hormones to control and regulate various functions.

Common mistake: Students might mistakenly choose the pituitary gland, often called the 'master gland', but it produces hormones that control other glands, not insulin directly.

Most bony fish possess a gas-filled organ called a swim bladder, which is also correctly referred to as an air bladder. This structure allows the fish to control its buoyancy and maintain a certain depth in the water without having to expend energy swimming. By regulating the amount of gas inside this bladder, the fish can adjust its overall density to match the water, preventing it from sinking.

Common mistake: Students often mistakenly choose option C, incorrectly assuming that fish have air sacs or air in their bones for buoyancy, which are adaptations typically found in birds for flight.

In genetics, an organism is described as heterozygous when it possesses two different alleles for a specific gene. For example, if a gene for height has alleles 'T' (tall) and 't' (short), a heterozygous individual would have the genotype 'Tt'. This contrasts with homozygous individuals who have two identical alleles (e.g., TT or tt).

Common mistake: Students often confuse heterozygous with homozygous, which refers to having two identical alleles for a gene, leading them to incorrectly choose option A.

The xylem is a specialized transport tissue in plants that functions like a system of pipes. Its primary role is to conduct water and dissolved mineral salts from the roots, where they are absorbed from the soil, up to the stem and leaves. This upward movement is crucial for photosynthesis and maintaining the plant's structure.

Common mistake: Students often confuse xylem with phloem, but phloem is the tissue responsible for transporting manufactured food, like sugars, from the leaves to other parts of the plant where it is needed.

Abiotic ecological factors are non-living physical and chemical components of an ecosystem that affect living organisms. Temperature is a physical factor that significantly influences the life processes and distribution of organisms, making it an abiotic factor. Other examples include light, water, and soil.

Common mistake: Students often confuse abiotic factors with biotic interactions. Options B, C, and D (Competition, Predation, Symbiosis) are all examples of interactions between living organisms, which are biotic factors.

Fertilization is the crucial process where male and female gametes (sex cells) fuse together. This fusion results in the formation of a zygote, which is the initial stage of a new, developing organism. It is fundamental to sexual reproduction in both plants and animals.

Common mistake: Students might confuse pollination with fertilization, but pollination is merely the transfer of pollen, while fertilization is the actual fusion of gametes.

Behavioral adaptations are actions or ways an organism behaves to survive in its environment. Hibernating (or aestivating, which is dormancy during hot periods) is a behavioral strategy where an animal becomes inactive to avoid the extreme heat and conserve energy. This helps the organism survive harsh environmental conditions like a hot climate.

Common mistake: Students often confuse behavioral adaptations with structural or physiological adaptations. Options B and D describe structural or physiological changes, not behaviors, while option C is a maladaptive behavior for a hot climate.

The natural place where an organism or a community of organisms lives is called its habitat. A habitat provides all the necessary resources like food, water, and shelter for the organisms residing there. Understanding habitats is fundamental to studying ecological factors and how organisms adapt to their specific environments.

Common mistake: Students often confuse 'habitat' with 'niche', which refers to the role an organism plays in its environment, or 'biome', which is a much larger geographical area.

Nitrogen fixation is a crucial process within the nitrogen cycle, which is an integral part of an ecosystem's nutrient cycling. During nitrogen fixation, atmospheric nitrogen gas (N2) is converted into ammonia (NH3) or ammonium (NH4+) by specialized bacteria. These forms can then be further processed into nitrates, which are readily absorbed and utilized by plants for their growth and development.

Common mistake: Students might confuse nitrogen fixation with denitrification, which is the process that returns nitrogen gas to the atmosphere, making it unavailable to plants.

Homeostasis is the process of keeping the internal body environment stable. The skin plays a crucial role in this by regulating body temperature. When the body is hot, sweat glands release sweat onto the skin's surface, and as this sweat evaporates, it removes heat and cools the body down.

Common mistake: Students might mistakenly choose 'Filtration of blood' because they associate waste removal with excretion, but this specific function is performed by the kidneys, not the skin.

Laterite soil is a type of soil commonly found in hot, wet tropical regions like Nigeria. The intense and heavy rainfall in these areas causes a process called leaching, where essential water-soluble nutrients like calcium and potassium are washed away from the topsoil. This process leaves behind less soluble and less fertile compounds like iron and aluminum oxides, which makes the soil poor for farming.

Common mistake: Students might choose 'Red soils' because laterite soils are typically reddish in colour, but 'laterite' is the specific term for soil formed by the intense tropical weathering and leaching described in the question.