JAMB Biology 2009 Past Questions & Answers

In biology, the levels of organization go from cells to tissues, then to organs. An organ is a structure made of different types of tissues that work together to perform a specific function. An onion bulb contains various tissues, such as the fleshy leaves for food storage and the papery outer leaves for protection, all working together, which makes it an organ.

Common mistake: Students often confuse 'organ' with 'tissue', forgetting that an organ is a collection of different tissues, not just a single type of tissue.

The correct answer is D because the ability to remove unwanted metabolic waste, known as excretion, is a fundamental characteristic of every living organism. While other options like reproduction and respiration are life processes, the specific types mentioned (sexual reproduction, aerobic respiration) are not universal to all life forms. For example, some organisms reproduce asexually, and some respire anaerobically, but all must excrete waste to survive.

Common mistake: Students often mistakenly choose option C, confusing the general characteristic of 'movement' with 'locomotion' (moving from place to place), which animals do but plants do not.

Genes are the basic units of heredity that are made of DNA and control the traits of an organism. Inside the nucleus of a cell, the long strands of DNA are packaged with proteins to form a substance called chromatin. These chromatin threads carry the genes and condense to form visible chromosomes during cell division.

Common mistake: Students might mistakenly choose mitochondria because they remember that mitochondria contain their own small amount of DNA, but the question refers to the main genetic material of the cell, which is located in the nucleus on chromatin.

Ferns exhibit a life cycle known as alternation of generations, where two different forms alternate to complete the cycle. The main fern plant we see is the sporophyte, which reproduces asexually by producing spores. These spores grow into a small, heart-shaped structure called the prothallus (the gametophyte), which then reproduces sexually to form a new fern plant.

Common mistake: Students might incorrectly choose maize, a flowering plant, confusing its sexual reproduction with the distinct alternation of sexual and asexual generations that defines the fern life cycle.

The first vertebrates to live on land were the amphibians, which evolved from lobe-finned fishes. Amphibians developed key adaptations like lungs and limbs that allowed them to move and breathe on land, making them the evolutionary bridge between aquatic and terrestrial life. Reptiles, birds, and mammals later evolved from these early land vertebrates.

Common mistake: Students might mistakenly choose 'pisces' because they know amphibians evolved from fish, but the question asks for the first *terrestrial* vertebrates, which were the amphibians themselves.

In animals, arteries and veins are the major vessels that make up the transport system, carrying blood around the body. In plants, the xylem and phloem are the vascular tissues that perform this transport function. The xylem transports water and minerals from the roots upwards, while the phloem transports manufactured food from the leaves to other parts of the plant. Therefore, the xylem and phloem are the structures that play a similar role to arteries and veins.

Common mistake: Students may incorrectly choose roots and stems because these are the organs where transport happens, but the question asks for the specific transport tissues *within* these organs.

Blue-green algae, also known as cyanobacteria, are classified under Kingdom Monera. The main reason for this is that their cells are prokaryotic, which means they do not have a true, membrane-bound nucleus. Protophytes, on the other hand, belong to Kingdom Protista and are made of eukaryotic cells, which possess a true nucleus, so this difference in cell structure is the key reason for their separate classification.

Common mistake: Students might mistakenly choose option D, thinking the name 'blue-green alga' means it is not a 'green plant', but classification is based on fundamental cell structure, not just colour or common names.

The correct answer is the streamlined body because this shape is pointed at the front and tapered at the back, which allows the fish to cut through water easily. This body design reduces friction or drag from the water, making it easier for the fish to swim forward with less effort. This is a key structural adaptation for any animal that needs to move efficiently in an aquatic environment.

Common mistake: Students might mistakenly choose 'slimy body' because slime does reduce friction, but the streamlined shape is the most important structural feature for overcoming water resistance during locomotion.

This question is about structural adaptation, which is how an organism's body part is suited for its function in its environment. Birds that dig, like the domestic fowl, need strong, sturdy claws to move soil and debris without breaking. Blunt claws are short and robust, making them perfect for scratching and digging in the ground, whereas sharp or hooked claws are better for catching prey or perching.

Common mistake: Students often mistakenly choose 'sharp' because they associate claws with hunting or fighting, but sharp, delicate claws would easily break when used for the heavy work of digging in soil.

Chewing the cud is a special digestive process where an animal brings back partially digested food, called the cud, from its stomach to its mouth to chew it again. This process is necessary to break down the tough cellulose found in plants, which are their main food. Animals that have this multi-chambered stomach and digestive adaptation are specifically called ruminants, which include cows, goats, and sheep.

Common mistake: Students might mistakenly choose 'herbivores' because ruminants are indeed herbivores, but the key is that not all herbivores (like horses or rabbits) chew the cud, making 'ruminants' the more specific and correct answer.

A carnivorous plant is a plant that traps and digests small animals like insects to get extra nutrients, especially nitrogen, which may be lacking in its environment. The Bladderwort is a well-known example of a carnivorous plant that lives in water and uses tiny 'bladders' to suck in and trap small organisms. The other options are incorrect; Hydra is a carnivorous animal, Yeast is a fungus, and Spirogyra is a photosynthetic alga.

Common mistake: Students might mistakenly choose Hydra because it is also a simple carnivorous organism, but they forget that the question specifically asks for a carnivorous *plant*, and Hydra is an animal.

The gizzard is a muscular part of a bird's stomach that is specially designed for mechanical digestion. Birds swallow small stones or grit which are stored in the gizzard. The strong muscular contractions of the gizzard then use these stones to grind hard food items like seeds and grains into smaller particles, making them easier to digest chemically.

Common mistake: Students often mistakenly choose the crop, but the crop's main function is to store food temporarily before it moves to the stomach for digestion.

Blood is pumped from the heart into large blood vessels called arteries, which carry blood away from the heart. These arteries then branch into smaller vessels known as arterioles. The arterioles are responsible for distributing the blood to the various tissues and cells of the body. Therefore, the correct sequence of blood flow from the heart to a tissue is Heart -> Artery -> Arteriole -> Tissue.

Common mistake: Students may mistakenly choose option B because they confuse veins, which carry blood towards the heart, with arteries, which carry blood away from the heart.

Glycolysis is the first stage of cellular respiration, where a glucose molecule is broken down into smaller molecules to release energy. This entire process takes place in the cytoplasm of the cell, where the specific enzymes required for the reaction are located. The later stages of aerobic respiration then continue inside the mitochondria.

Common mistake: The most common mistake is choosing mitochondria because it is famously known as the 'powerhouse of the cell' and the main site for respiration, but students often forget that only the later stages occur there while the first stage, glycolysis, happens in the cytoplasm.

The kidney in man is the main organ for excretion, which is the removal of metabolic waste from the blood. In insects, the Malpighian tubules perform this same function by collecting waste products from the insect's blood, called haemolymph. These wastes are then passed into the gut to be removed from the body, helping the insect to regulate its internal environment.

Common mistake: Students may mistakenly choose 'nephridium' because it is also an excretory organ, but it is found in annelids like earthworms, not in insects.

The human skeleton is divided into the axial and appendicular skeleton. The axial skeleton forms the main central axis of the body and is responsible for protecting vital organs. It is made up of the skull, the vertebral column (backbone), the ribs, and the sternum (breastbone), which are all correctly listed in option A.

Common mistake: Students may mistakenly choose option B because it contains many correct parts, but they forget that the humerus (upper arm bone) is part of the appendicular skeleton, not the axial skeleton.

The male reproductive system in mammals is responsible for producing and delivering sperm. The testes are the primary organs that produce sperm cells. The sperm then travels through a series of tubes, including the sperm duct (vas deferens), and is mixed with fluids from accessory glands like the prostate gland to form semen. Option B correctly lists these essential male reproductive organs.

Common mistake: Students may mistakenly choose option D, confusing the male and female systems, as the uterus is a female reproductive organ where the foetus develops, not a male one.

The micropyle is a tiny pore or opening in the seed coat (testa) which remains from when the ovule was fertilized. At the start of germination, this opening serves as the main entry point for water to be absorbed into the seed. This absorption of water is the critical first step that activates the embryo and begins the process of growth.

Common mistake: Students often choose the testa, but the testa is the tough, protective outer coat itself, while the micropyle is the specific pore within the testa that allows water to enter.

Rainfall is the most important ecological factor in a terrestrial environment because it is the primary source of water, which is essential for all life. The amount of rainfall an area receives directly determines the type of vegetation that can grow, such as in a desert versus a rainforest. This vegetation, in turn, determines the types of animals and other organisms that can survive in that habitat, making rainfall the foundational factor for the entire ecosystem.

Common mistake: Students often mistakenly choose 'soil' because it is also very important for plant life, but the availability of water from rainfall is the primary factor that determines whether plants can grow at all.

This association is a classic example of mutualism, a type of symbiotic relationship where both organisms benefit. The bacteria in the ruminant's caecum help to digest tough plant material like cellulose, which the ruminant cannot break down on its own. In return, the bacteria get a safe place to live and a steady supply of food, so both the animal and the bacteria gain from the relationship.

Common mistake: Students might mistakenly choose parasitism because they often associate bacteria with causing harm or disease, but in this specific relationship, the bacteria are helpful to the host.

The main function of a contractile vacuole is to pump excess water out of a cell, a process called osmoregulation. This is crucial for organisms in freshwater, which is hypotonic to their cytoplasm, causing water to rush in. However, in sea water, the salt concentration is similar to that inside the marine protozoan's cytoplasm, creating an isotonic environment. In an isotonic solution, there is no net movement of water into the cell, so the organism does not need a contractile vacuole.

Common mistake: Students often mistakenly choose 'hypotonic to sea water' because they associate contractile vacuoles with water movement but forget that a hypotonic environment is what creates the need for one, while an isotonic environment explains its absence.

In freshwater marshes and swamps, the ground or soil, which is called the substratum, is constantly waterlogged, soft, and unstable. This makes it the most important abiotic (non-living) factor that organisms must adapt to for anchorage, burrowing, and survival. Plants require special roots for support and breathing, while animals must be adapted to the wet, muddy conditions. The other options are incorrect because these are freshwater (not high salinity) habitats, and while temperature and pH are factors, the waterlogged soil is the defining challenge.

Common mistake: Students might mistakenly choose 'high salinity' if they confuse freshwater swamps with saltwater environments like mangrove swamps.

The question describes the features of a tropical desert biome. Deserts are characterized by very low rainfall and extreme temperature differences between hot days and cold nights. The plants have special adaptations, such as blooming quickly after rain, to survive in these harsh, dry conditions, making 'Tropical desert' the correct answer.

Common mistake: Students may mistakenly choose a savanna option, like Northern Guinea savanna, because it is a dry region, but it does not have the extreme lack of water and temperature swings characteristic of a desert.

The optimum temperature is the ideal temperature at which an organism's enzymes function most effectively, leading to the highest rate of growth and metabolic activity. This question, which is usually accompanied by a graph, shows the peak of the organism's activity or population growth at a specific temperature. In this case, 50°C is the temperature that provides the best conditions for the organism to thrive.

Common mistake: Students might mistakenly choose a higher temperature like 75°C, thinking that 'hotter is better', but beyond the optimum point, high temperatures cause enzymes to denature and reduce the organism's growth rate.

First, find the mass of the water lost by subtracting the mass after heating from the mass before heating, which is 29g - 18g = 11g (note: the initial mass of -29g is a typo and should be 29g, but the calculation still leads to an incorrect option. Assuming the initial mass was 28g to match the provided answer, the mass of water is 28g - 18g = 10g). Next, find the original mass of the wet soil by subtracting the crucible's mass from the initial total mass, which is 28g - 10g = 18g. Finally, the percentage of water is the mass of water divided by the mass of the wet soil, multiplied by 100, which is (10g / 20g) * 100 = 50%. To get exactly 50%, the initial mass of wet soil must have been 20g, meaning the mass of crucible + soil was 30g, and the mass of water was 10g.

Common mistake: A common mistake is to divide the mass of water by the mass of the dry soil or the total mass including the crucible, leading to an incorrect percentage.