JAMB Biology 2013 past questions and answers

Catabolism is the breakdown part of metabolism (e.g. respiration), while anabolism builds complex substances up. Tropism is a plant growth movement, not a chemical process.

Euglena has a red eyespot near the base of its flagellum that detects light, so it can swim towards light for photosynthesis.

Taenia solium is the pork tapeworm: its larval stage lives in the muscles of the pig, which is its secondary host.

The diagram shows an earthworm; II points to the thick swollen band near the front, the clitellum, which secretes the cocoon.

The earthworm feeds on decaying organic matter and needs moist soil, so it is found in soil rich in humus.

Arthropods have an exoskeleton made of chitin; they have many pairs of jointed limbs, segmented bodies, and must moult to grow.

Moths have stout, hairy, fat abdomens, while butterflies are slender. Moths are active at night, the antennae differ, and it is the moth that rests with wings spread flat.

Quill feathers on the wings and tail are long and stiff and push against the air in flight. Down feathers keep the bird warm.

Xerophytes are plants adapted to very dry places, such as cactus. Hydrophytes live in water and mesophytes in moderately wet places.

A virus is just genetic material in a protein coat with no cell at all, so it is simpler than any single-celled organism.

A proboscis is a long tube-like mouthpart for sucking, found in insects such as butterflies, mosquitoes and houseflies.

Leaves reduced to spines have very little surface, so the plant loses much less water by transpiration.

Birds of prey such as hawks use their long, sharp claws (talons) to seize and hold their prey; the beak is used for tearing.

Anabaena is a blue-green alga with chlorophyll, so it makes food using light energy. Nitrosomonas, Nitrobacter and sulfur bacteria get their energy from chemical reactions (chemosynthesis).

Translocation is the movement of dissolved substances such as sugars and minerals from one part of a plant to another.

Saliva contains ptyalin (salivary amylase), which starts the digestion of starch in the mouth. Pepsin and rennin work in the stomach.

Insectivorous (carnivorous) plants like sundew and pitcher plant trap insects and digest them to get nitrogen.

Respiration breaks down food such as glucose and stores the energy released in ATP. Photosynthesis does the opposite job, trapping light energy in food.

Without chlorophyll fungi cannot make their own food, so they must feed on other organic matter, which makes them heterotrophs.

Plasmodium lives in human blood and liver cells and causes malaria. The others are free-living.

Lymphocytes make antibodies and recognise particular germs, which is the immune response. Red cells (erythrocytes) carry oxygen.

Blood is pumped by the heart into arteries, passes through capillaries in the tissues and returns in veins.

Xylem carries water and dissolved mineral salts up from the roots; phloem carries manufactured food.

Platelets release thrombokinase at a wound, starting the reactions that turn fibrinogen into a fibrin clot.

Plasma, the pale yellow liquid part of blood, makes up about 55% of its volume; the cells make up the rest.

Sweat glands remove water, salts and a little urea from the body in sweat, so they are the excretory part of the skin.

Insects excrete nitrogen as solid uric acid through their Malpighian tubules, which saves water. Mucilage and alkaloids are plant products.

The skeleton gives the body its shape, supports it and protects organs such as the brain, heart and lungs.

Pollination is the transfer of pollen from anther to stigma; fertilization is the later fusion of the male and female gametes.

The stamen (anther and filament) produces pollen, so it is the male part. The carpel is the female part.

The pituitary gland hangs just below the hypothalamus at the base of the brain and is controlled by it.

Auxins control many key processes such as cell elongation, tropisms, root formation and apical dominance, so they are regarded as the main plant hormone.

Rods in the retina are very sensitive and work in dim light; cones need bright light and detect colour.

Without ADH the kidney tubules reabsorb little water, so large amounts of dilute urine are lost and the body becomes more and more dehydrated.

Oestrogen, the main female sex hormone, is made by the ovaries (in the developing follicles).

In a cataract the lens becomes cloudy so light cannot pass through clearly. Glaucoma is high pressure in the eye.

Sewage is organic waste that bacteria and fungi can break down, so it is biodegradable. Heavy metals and cellophane are not broken down by microbes.

Trypanosoma, spread by the tsetse fly, causes sleeping sickness. Malaria is caused by Plasmodium and yellow fever by a virus.

The lithosphere is the rock and soil (solid) part of the earth; the hydrosphere is water and the atmosphere is air.

Treponema pallidum is the spiral bacterium that causes syphilis. Gonorrhoea is caused by Neisseria.

Group AB has no anti-A or anti-B antibodies in its plasma, so it can receive blood from all groups.

Agglutination is the clumping of red cells when antibodies react with antigens of an incompatible blood group.

In cactus the leaves are reduced to spines, which cuts down water loss by transpiration; the green stem does the photosynthesis.

Birds of prey such as eagles hold prey with sharp claws (talons) and tear the flesh with a strong hooked beak.

Chameleons change colour using chromatophores, special pigment cells in the skin that spread or concentrate their pigment.

In social insects such as termites and bees, members of different castes live together and depend on each other, so the relationship benefits all of them.