JAMB Biology 2010 Past Questions & Answers

A key feature of a mature plant cell is the presence of a large central vacuole which takes up most of the cell's volume. This large vacuole pushes the cytoplasm and the nucleus to the very edge of the cell, pressing them against the rigid cell wall. Due to this pressure, the nucleus can be flattened into an irregular shape and appears relatively small compared to the large size of the entire mature cell.

Common mistake: Students often mistakenly choose option C because while it is true that a plant cell wall is made of cellulose, this feature is present in both young and mature cells and is not a distinguishing characteristic of maturation.

The nucleus is known as the control centre of the cell because it contains the genetic material (DNA) that directs all cell activities and carries hereditary information. The part of the cell responsible for producing and storing energy is the mitochondrion, often called the 'powerhouse' of the cell. Therefore, being a reservoir of energy is not a function of the nucleus, making option D the correct answer.

Common mistake: Students might get confused and select option B, mixing up the process of transcription (reading DNA to make mRNA in the nucleus) with translation (using mRNA to make protein at the ribosome).

Ferns have a life cycle with two distinct stages, known as alternation of generations. The sporophyte is the large, leafy plant we commonly see, which produces spores, while the gametophyte (or prothallus) is a much smaller, heart-shaped structure. The sporophyte is the dominant phase because it is the larger, more visible, and longer-lasting stage of the fern's life.

Common mistake: Students often mistakenly choose 'gametophyte' or 'prothallus' because they confuse the fern's life cycle with that of mosses, where the gametophyte is the dominant phase.

Parental care refers to the behaviours animals exhibit to ensure the survival of their offspring. Birds are well-known for their advanced parental care, which includes building nests, incubating eggs to keep them warm, and feeding the young chicks after they hatch. This high level of investment increases the chances of their young surviving to adulthood.

Common mistake: Students might mistakenly choose toads because some amphibian species show limited forms of parental care, but it is not as complex or common as the care exhibited by birds.

Organisms that are 'devoid of true nuclei' are called prokaryotes, meaning their genetic material is not enclosed within a membrane. The Kingdom Monera is the classification group that includes all prokaryotic organisms, such as bacteria. In these cells, the genetic material floats in the cytoplasm in a region called the nucleoid. Algae and Fungi are eukaryotes and possess a well-defined, membrane-bound nucleus.

Common mistake: Students often mistakenly choose 'viruses' because they are simple and lack a nucleus, but viruses are not considered true cells.

In the transverse section of a dicotyledonous stem, the vascular bundles are arranged in a ring. Each vascular bundle contains xylem for water transport and phloem for food transport. The phloem is always located towards the outer part of the stem, while the xylem is located towards the inner part, making the xylem more interiorly located.

Common mistake: Students often confuse the arrangement of vascular bundles in dicot stems with that of monocot stems, leading them to incorrectly choose option D, which describes the scattered bundles found in monocots.

Kwashiorkor is a severe form of malnutrition specifically caused by a diet that is very low in protein, even if it contains enough calories from other food classes like carbohydrates. Proteins are the body's building blocks, essential for growth, repair, and making enzymes. Without enough protein, a person, usually a child, develops symptoms like a swollen abdomen (oedema), stunted growth, and changes in skin and hair.

Common mistake: Students often confuse kwashiorkor with marasmus and might incorrectly choose carbohydrates, but marasmus is caused by a general deficiency of all nutrients and energy, not just protein.

Sundew and bladderwort are carnivorous plants that trap and digest insects to get extra nutrients, especially nitrogen, which is lacking in their environment. This mode of feeding, which involves ingesting solid organic food and digesting it internally, is known as holozoic nutrition. While these plants also perform photosynthesis, their insect-eating adaptation is a key part of how they survive.

Common mistake: Students often mistakenly choose 'autotrophic' because they know sundew and bladderwort are plants and assume all plants only make their own food through photosynthesis.

Benedict's solution is the chemical reagent used to test for the presence of reducing sugars, such as glucose. For the test to work, the mixture of the food substance and the solution must be warmed. A positive result is indicated by a colour change from the original blue to green, yellow, orange, and finally a brick-red precipitate, which confirms that a reducing sugar is present.

Common mistake: Students often mistakenly choose sucrose because it is a type of sugar, but they forget that it is a non-reducing sugar and will not give a positive result with Benedict's solution unless it is first broken down.

The heart is the organ responsible for pumping blood, and its chambers, the ventricles, do the main work. The left ventricle has the thickest and most muscular wall of all the heart chambers. This powerful muscle is necessary to generate enough pressure to pump oxygenated blood to all parts of the body, making it the primary pumping structure for systemic circulation.

Common mistake: Students may mistakenly choose arteries because they carry high-pressure blood away from the heart, but arteries are the vessels, not the muscular pump that creates the pressure.

The human circulatory system is a double-circuit system with two main parts. Systemic circulation is the pathway that carries oxygenated blood from the heart to all other parts of the body and returns deoxygenated blood to the heart. The other part, pulmonary circulation, specifically handles blood flow only between the heart and the lungs. Therefore, circulation to all parts of the body except the lungs is called systemic circulation.

Common mistake: Students often confuse the two circuits and may choose 'pulmonary circulation', forgetting that the word 'pulmonary' specifically refers to the lungs.

Yeast carries out anaerobic respiration, which is the breakdown of food substances to release energy in the absence of oxygen. This process, also known as fermentation, converts simple sugars like glucose into ethanol (an alcohol) and carbon (IV) oxide. This is why alcohol is the correct product alongside carbon (IV) oxide.

Common mistake: Students may mistakenly choose 'water' because water is a major product of aerobic respiration (respiration with oxygen), and they often confuse the products of the two types of respiration.

The diaphragm is the correct answer because it is a large, dome-shaped sheet of muscle that physically separates the thoracic (chest) cavity from the abdominal cavity. It is the main muscle responsible for breathing. When the diaphragm contracts and moves down, it increases the volume of the chest cavity, allowing the lungs to expand and draw in air.

Common mistake: Students may confuse the diaphragm with the intercostal muscles because both are involved in breathing, but the intercostal muscles are located between the ribs, not between the two major body cavities.

The sebaceous glands are small glands found in the skin of mammals, usually attached to hair follicles. They produce and secrete an oily substance called sebum. This sebum lubricates the hair and the outer layer of the skin, keeping them flexible and providing a waterproof coating.

Common mistake: Students often confuse sebaceous glands with sweat glands, but sweat glands produce sweat (a watery fluid) for cooling the body, not an oily substance for lubrication.

The kidney is made up of an outer part and an inner part. The outer part is called the cortex, and this is where you find the Bowman's capsules. These capsules are responsible for the first step of filtering waste from the blood to form urine. The inner part, known as the medulla, contains other structures like the loops of Henle.

Common mistake: Students often confuse the cortex with the medulla, but the medulla is the inner region of the kidney containing the loops of Henle and collecting ducts, not the Bowman's capsules.

A nastic response is a non-directional movement of a part of a plant in response to an external stimulus. The classic example is the folding of the leaves of a Mimosa plant when touched, which happens regardless of the direction of the touch. This response to touch is known as thigmonasty. Responses to stimuli like light intensity and gravity are typically directional movements called tropisms, not nastic responses.

Common mistake: Students often confuse nastic movements with tropisms, so they might incorrectly choose light or gravity, which cause directional growth movements rather than the non-directional response asked for in the question.

Sperm cells are produced in the seminiferous tubules inside the testes. After production, they move to the epididymis, which is a long, coiled tube where they mature and are stored. The vas deferens is the tube that transports sperm from the epididymis, but the main storage site is the epididymis itself.

Common mistake: Students often mistakenly choose the seminiferous tubules because that is where sperm is produced, but the epididymis is where the sperm is stored and matured.

Chemosynthesis is a process where certain organisms, like some bacteria, produce their own food using energy from chemical reactions instead of sunlight. They achieve this by oxidizing simple inorganic compounds, such as hydrogen sulphide or ammonia. This oxidation process releases the chemical energy needed to convert simple substances like carbon dioxide into complex organic food molecules.

Common mistake: Students might mistakenly choose 'reduction' because both oxidation and reduction are fundamental chemical processes in metabolism, and they can easily confuse which one is responsible for releasing the initial energy in this specific context.

The stomach is the correct answer because its walls contain glands that secrete hydrochloric acid (HCl). This strong acid helps to kill harmful germs in the food and provides the acidic condition needed for the enzyme pepsin to begin the digestion of proteins. The other parts of the gut listed are either neutral or alkaline.

Common mistake: Students might mistakenly choose the duodenum because it is the first part of the intestine to receive acidic food from the stomach, but its environment is quickly made alkaline by secretions from the pancreas and liver.

The correct match is the contractile vacuole with protozoa. Protozoa like Amoeba and Paramecium are single-celled organisms that live in water and use the contractile vacuole to pump out excess water, a process called osmoregulation which is a form of excretion. The other options are incorrect: stomata are for gas exchange in plants, alveoli are in the lungs of mammals, and malpighian tubules are excretory organs in insects, not mammals.

Common mistake: Students might mistakenly choose option A, confusing the Malpighian tubules of insects with the Malpighian body (renal corpuscle) which is part of the kidney in mammals.

A food chain shows how energy flows from one living thing to another. It must always begin with a producer, which is an organism like a green plant that creates its own food from sunlight through photosynthesis. All other organisms, called consumers, get their energy by eating the producers or other consumers, so the producer is the foundation.

Common mistake: Students sometimes mistakenly choose 'primary consumer' because it is the first organism that eats, but the food chain itself begins with the producer that is being eaten.

Mycorrhizae is a symbiotic relationship between a fungus and plant roots, which is a topic under plant nutrition. The fungus forms a large network of fine threads in the soil that act as an extension of the plant's root system. This vast network is excellent at absorbing inorganic ions, like phosphates, and water from the soil, which it then passes to the plant, boosting its growth.

Common mistake: Students often confuse the role of mycorrhizal fungi with that of nitrogen-fixing bacteria, incorrectly choosing option C which describes nitrogen fixation in legumes.

The placenta is a special organ that develops in the uterus during pregnancy, connecting the mother and the foetus. It acts as a selective barrier, preventing the direct mixing of maternal and foetal blood. This barrier allows for the exchange of nutrients, oxygen, and waste products between the mother and the developing baby.

Common mistake: Students often mistakenly choose the umbilical cord because it connects the foetus to the placenta, but the cord itself is a conduit for blood vessels, not the actual barrier where exchange happens.

Erythrocytes, which are also called red blood cells, are the correct answer. These cells contain a special iron-rich protein called haemoglobin, which has a very high affinity for oxygen. This allows the blood to efficiently pick up oxygen from the lungs and transport it to all the tissues and organs in the body that need it for energy.

Common mistake: Students might mistakenly choose leucocytes because they are also a major blood component, but their primary function is fighting infection, not carrying oxygen.

The question asks to identify an organism that lives in a marine (saltwater) habitat. The Dog fish is a type of shark, which is a cartilaginous fish adapted to live in the sea or ocean. Achatina (snail) and Tortoise are terrestrial (land) animals, while Tilapia is a bony fish that primarily lives in freshwater habitats like rivers and lakes.

Common mistake: Students often choose Tilapia because it is a well-known fish, but they mistakenly assume all fish live in the sea, forgetting that Tilapia is a freshwater fish.