JAMB Biology 2007 Past Questions & Answers

Members of the Kingdom Monera, such as bacteria, are prokaryotes. A key feature of prokaryotic cells is that they do not have a true nucleus with a surrounding membrane. Therefore, their genetic material, the chromosome, is located freely within the cytoplasm in a region known as the nucleoid.

Common mistake: Students often mistakenly choose 'nucleus' because they remember that chromosomes are typically found in the nucleus, but they forget that this rule only applies to eukaryotes, not prokaryotes like Kingdom Monera.

Ferns are lower plants that require water for their reproductive cycle to be complete. They produce motile male gametes, called antherozoids, which have flagella that allow them to swim. For fertilization to occur, these antherozoids must swim through a thin layer of water to reach the egg cell located in the archegonium.

Common mistake: Students may mistakenly choose angiosperms because they are familiar flowering plants, but they forget that angiosperms use pollen tubes for fertilization, not swimming sperm that require water.

Ecdysis is the correct scientific term for the process where an arthropod, like an insect or a crab, sheds its rigid outer skeleton, called an exoskeleton. This shedding, also known as moulting, must happen regularly to allow the animal to increase in size and grow. The old exoskeleton is split and the animal emerges, later hardening a new, larger one.

Common mistake: Students may confuse ecdysis with 'metamorphosis', but metamorphosis is the overall change in body form (like a larva to an adult), while ecdysis is the specific act of shedding the exoskeleton to allow for growth.

The question shows a unicellular organism, and the part labeled IV is the contractile vacuole. The primary function of the contractile vacuole is osmoregulation, which is the process of controlling the water balance inside the cell. Because the organism lives in freshwater, water continuously enters its cell by osmosis, and the contractile vacuole collects this excess water and pumps it out to prevent the cell from swelling and bursting.

Common mistake: Students may confuse the contractile vacuole with the food vacuole and incorrectly choose 'ingestion', as both are types of vacuoles found within the cell but with different functions.

The correct answer is that they all undergo complete metamorphosis. This is a developmental process where an insect goes through four distinct stages: egg, larva, pupa, and adult. The mosquito (larva is a wriggler), housefly (larva is a maggot), and blackfly all have these four stages in their life cycle, making it a common feature among them.

Common mistake: Students often mistakenly choose option A because they know mosquito larvae are aquatic, but they forget that housefly larvae (maggots) typically live in decaying matter on land, not in water.

The question requires identifying the organism with the most basic respiratory system. A land snail uses a simple lung, which is a basic cavity with a moist surface and a rich blood supply for gas exchange. This structure is less complex than the well-developed gills of a fish, the highly specialized tracheal system of an insect, or the advanced lungs with alveoli found in a mouse, making it the most primitive among the choices.

Common mistake: Students might mistakenly choose 'insect' because its tracheal system is very different from lungs, but this system is actually a highly specialized and efficient adaptation, not a primitive one.

Monocot stems, like those of maize, lack a cambium layer. The cambium is a special tissue found between the xylem and phloem in dicot stems, and it is responsible for secondary growth which makes the stem grow thicker. Because monocots do not have this cambium, their vascular bundles are scattered and they cannot increase in girth.

Common mistake: Students often mistakenly choose option A, getting confused because monocots actually have numerous, scattered vascular bundles, not fewer of them.

The adrenal gland is the correct answer because it is an endocrine gland located on top of each kidney. Its name even gives a clue, as 'ad-' means near and '-renal' refers to the kidney. These glands are part of the hormonal system and produce important hormones like adrenaline, which prepares the body for stress.

Common mistake: Students might confuse the adrenal gland with the pancreas because both are glands located in the abdominal cavity, but the pancreas is situated behind the stomach, not on the kidney.

Photosynthesis is the process where plants make their own food using sunlight. To do this, they need to capture the sun's energy, and they use special molecules called pigments for this job. The main pigment is chlorophyll, which is green, but plants also have other 'accessory' pigments like carotenoids (which are yellow, orange, or red) to help absorb more light.

Common mistake: Students often mistakenly choose option D because they know photosynthesis occurs in the chloroplast, but a chloroplast is an organelle (a part of the cell), not a pigment itself.

The pancreas is a vital organ in digestion that produces pancreatic juice, which contains a mixture of powerful enzymes. These enzymes include pancreatic amylase for digesting carbohydrates, trypsin for digesting proteins, and lipase for digesting fats. These enzymes are released into the small intestine to break down these major food classes into smaller molecules for absorption.

Common mistake: Students might mistakenly choose option B because they know vitamins are essential nutrients, but they forget that vitamins are small molecules that are absorbed directly without needing to be digested by enzymes.

The earthworm carries out gaseous exchange through its moist body surface or skin. This thin, moist skin is rich in blood capillaries, allowing oxygen from the air to dissolve in the moisture and diffuse directly into the blood, while carbon dioxide diffuses out. This process is known as cutaneous respiration and relies principally on diffusion across the body surface.

Common mistake: Students might mistakenly choose the grasshopper, but it uses a tracheal system of tubes (tracheae) and openings (spiracles) to carry air directly to its tissues, which is a more complex system than simple diffusion across the skin.

The opening and closing of the stoma are controlled by the turgor pressure of the guard cells. When guard cells absorb water by osmosis, they become turgid (swollen) and curve outwards, which opens the stoma. When they lose water by osmosis, they become flaccid (limp) and the stoma closes.

Common mistake: Students often mistakenly choose transpiration because it is the process of water loss that occurs through the stomata, but it is osmosis that actually controls the opening and closing of the stomata themselves.

Plants produce various waste products from their metabolic activities, which are stored in different parts like leaves, bark, or old wood. Tannin is one such waste product, a bitter-tasting chemical that is stored in plant tissues. This chemical has the special ability to bind to the proteins in animal hides, preventing them from decaying and turning them into durable leather.

Common mistake: Students often confuse tannin with other plant excretory products like resin or gum, but only tannin has the specific chemical property used for tanning leather.

Urine formation begins in the kidney when blood is filtered from the glomerulus into the Bowman's capsule. The resulting filtrate then travels through the proximal convoluted tubule, down and up the loop of Henle, and then through the distal convoluted tubule. This path allows for the reabsorption of useful substances and water, concentrating the urea. Finally, the remaining fluid, which is now urine, passes into the collecting tubule for excretion.

Common mistake: Students often choose option B because it has the correct starting sequence, but they forget that the filtrate must pass through both the proximal and distal convoluted tubules before reaching the collecting tubule.

A composite fruit, also known as a multiple fruit, is formed from the ovaries of many separate flowers that are clustered together in an inflorescence. The pineapple develops this way, where the entire cluster of flowers fuses together to form one large fruit. This is different from a simple fruit (like a mango) which develops from a single ovary in a single flower.

Common mistake: Students often confuse composite fruits with aggregate fruits, which develop from a single flower that has many separate ovaries, like a strawberry.

Calcium is an essential macronutrient for plants, playing a vital role in building strong cell walls and in cell division. It is especially important for the growth of new tissues like root tips and young leaves. Therefore, a deficiency in calcium directly weakens these growing parts, leading to the described symptoms of stunted growth and poor root development.

Common mistake: Students may mistakenly choose phosphorous because it is also well-known to be essential for root growth, but its deficiency typically causes purplish leaves rather than the specific stunting mentioned.

The levels of ecological organization show increasing complexity from population, to community, and then to an ecosystem. An ecosystem includes all the living organisms (the entire community) and their interactions with the non-living parts of their environment, like water and soil. While the biosphere is the largest zone containing life, the ecosystem is the highest complete functional unit where biotic and abiotic factors interact.

Common mistake: The most common mistake is choosing 'biosphere' because it is technically the largest ecological level, but in the context of functional organization, the ecosystem is often considered the highest complete system.

In ecology, factors are divided into biotic (living) and abiotic (non-living). Biotic factors are the influences that living organisms have on each other within an ecosystem. Competition for resources like food, mates, and territory is a direct interaction between living organisms, making it a key biotic factor that determines where and how many organisms can survive. The other options—temperature, light, and pH—are non-living, physical conditions, so they are abiotic factors.

Common mistake: Students often confuse biotic and abiotic factors, choosing options like temperature or light because they are well-known factors that affect organisms, without remembering that 'biotic' specifically means living.

Parasitism is a relationship where one organism, the parasite, lives on or in another organism, the host, and benefits by causing harm to it. The mistletoe plant grows on the orange tree, taking water and nutrients from it for survival. This action harms the orange tree, making it a clear example of parasitism.

Common mistake: Students may mistakenly choose option C, confusing parasitism with mutualism, where both the cattle (gets ticks removed) and the egret (gets food) benefit from the interaction.

Vibrissae, also known as whiskers, are long, stiff hairs on the rat's face that are highly sensitive to touch. In dark underground habitats where it is difficult to see, these whiskers act as feelers. They help the rat detect objects, navigate through tight spaces, and understand its immediate environment without needing to use its eyes.

Common mistake: Students might mistakenly choose 'Eyes' because they are the primary organs for navigation in many animals, but they forget that eyes are not effective in the complete darkness of an underground habitat.

Hydrophytes are plants that live in water, so they are always surrounded by it. Because water is readily available, they do not need large, deep root systems to search for it. The water also provides support through buoyancy, which means they do not need strong, woody xylem tissues for structural support like land plants do. Therefore, having poorly developed roots and xylem is a key adaptation to their aquatic habitat.

Common mistake: Students often mistakenly choose options like 'leaves reduced to spines', remembering that this is an adaptation, but they forget it is for plants in dry environments (xerophytes) to reduce water loss, not for plants living in water.

Mangrove swamps are special ecosystems that grow in salty, coastal waters with high rainfall and humidity. In Nigeria, these specific conditions are found in the coastal areas of the Tropical Rainforest belt, especially in the Niger Delta. The savanna belts, such as Guinea, Sudan, and Sahel, are much drier and located further north, so they cannot support mangrove forests.

Common mistake: Students may confuse the different vegetation zones and incorrectly select Guinea savanna, not realizing that savannas are grasslands and lack the coastal, water-logged conditions that mangroves require.

Montane vegetation refers to plants adapted to living in high-altitude environments like mountains and plateaus where the climate is cooler. In Nigeria, the Jos Plateau, located in Plateau State, is a major highland region. These specific ecological factors (high altitude and lower temperatures) support the growth of montane vegetation, making Plateau State the correct answer.

Common mistake: Students might incorrectly choose Taraba because it also has mountainous areas like the Mambilla Plateau, but the Jos Plateau is the most prominent and classic example of this vegetation zone in Nigeria.

Soil is made up of mineral particles of different sizes. Clay has the finest and smallest particles, which makes it feel smooth and sticky. Silt particles are slightly larger than clay, followed by sand particles which are coarser and feel gritty. Gravel consists of the largest particles, which are essentially small stones, so the correct increasing order of size is clay, silt, sand, and gravel.

Common mistake: Students often confuse the relative sizes of clay and silt, sometimes incorrectly believing silt is smaller than clay, which would lead them to choose an option like B.

First, find the weight of the fresh soil by subtracting the crucible's weight from the total weight (10g - 5g = 5g). Next, find the weight of the water lost during heating by subtracting the final weight of the crucible and dry soil from the initial weight of the crucible and fresh soil (10g - 8g = 2g). To find the percentage of water, divide the weight of the water by the weight of the fresh soil and multiply by 100, which is (2g / 5g) x 100 = 40%.

Common mistake: Students often make the mistake of dividing the weight of the water (2g) by the total initial weight of the crucible and soil (10g), which incorrectly gives 20%.