2024 - JAMB Biology Past Questions and Answers - page 7

Discontinuous variation refers to traits that have distinct categories with no intermediate forms. Blood group is a classic example of discontinuous variation because individuals are classified into distinct blood types (A, B, AB, or O) with no in-between categories. The other options, such as shape of the head, body complexion, and pointed nose, are examples of continuous variation because they show a range of forms, with many intermediate categories.

The diagram likely depicts a single-celled eukaryotic organism, which best fits the characteristics of organisms belonging to the Kingdom Protista. Protists are a diverse group of eukaryotic organisms that are neither animals, plants, nor fungi.

Cockroaches are known vectors of disease. They can contaminate food with various pathogens, leading to the transmission of diseases like salmonellosis, gastroenteritis, and other foodborne illnesses. The other options are not directly linked to the contamination of food and the subsequent transmission of diseases in the same way.

The bacteria in the large intestine are beneficial microorganisms that help in various ways, including the synthesis of certain vitamins. Here's why:

• Vitamins: Bacteria in the large intestine synthesize vitamins like vitamin K and some B vitamins.
• Minerals: Minerals are absorbed in the large intestine, but they are not synthesized there. Bacteria do not synthesize them.
• Glucose and amino acids: The primary source for glucose and amino acids is the digestion of food in the small intestine, not the large intestine.

The equation represents photosynthesis.

• I represents the reactants, which in this case are the 6 molecules of carbon dioxide which reacts with 6 molecules of water.
• H₂O represents water. Therefore, the part labeled I represents water.

Energy transfer in both plants and animals primarily occurs through the molecule Adenosine Triphosphate (ATP). ATP acts as the main energy currency of cells, storing and releasing energy to fuel various cellular processes.

The Northern Guinea savanna is a vegetation zone found in Nigeria. Kano state is predominantly located within this vegetation zone.

Organic evolution is the change in the characteristics of living organisms over generations. This includes the processes of natural selection, genetic drift, and mutation, leading to the diversity of life we see today.

The mouthparts of insects are highly specialized depending on their feeding habits.

• Mosquitoes have mouthparts that are adapted for piercing skin and sucking blood. The female mosquito uses these to obtain a blood meal.
• Houseflies have sponging mouthparts for lapping up liquid food.
• Grasshoppers and Cockroaches have chewing mouthparts adapted for biting and grinding solid food.

Earthworms excrete nitrogenous waste products through their metanephridia. The primary waste product is ammonia, which is a highly toxic substance. Since earthworms live in moist environments, they can readily eliminate ammonia through diffusion across their body surface.