JAMB Biology 2004 Past Questions & Answers

The rods are specialized photoreceptor cells located in the retina of the eye, which is a sense organ. Their main function is to detect light, especially in dim conditions. While many of these cells group together to form the retinal tissue, a single rod is a cell, the basic structural and functional unit of an organism.

Common mistake: Students may mistakenly choose 'Tissues' because many rod cells are grouped together in the retina, but the question asks to classify a single rod, which is a cell.

The question is about why some plants cannot grow large. Large plants need special 'pipes' called vascular tissues (xylem and phloem) to transport water and food efficiently over long distances. Algae, liverworts, and mosses do not have these true transport systems, so they rely on slow methods like diffusion, which only works for small organisms. This lack of an efficient transport system is what restricts their body size.

Common mistake: Students often mistakenly include ferns (pteridophytes) in this group, but ferns are actually the first major plant group to evolve proper vascular tissues, which allows them to grow much larger than mosses.

Euglena is a unique organism with both plant and animal features, placing it in Kingdom Protista. The pigment spot, also called the eyespot, is a plant-like feature because it is sensitive to light. This allows the Euglena to move towards a light source to perform photosynthesis, which is the process plants use to make their own food.

Common mistake: Students often mistakenly choose 'Pellicle' because it is a well-known structure in Euglena, but it is an animal-like feature for support and movement, not a plant-like one.

The question asks for the most common characteristic of fungal hyphae. A key feature that distinguishes Kingdom Fungi from other kingdoms, like plants, is the chemical composition of their cell walls. Fungal cell walls are made of a tough, rigid substance called chitin, which is the same material found in the exoskeletons of insects. This is a universal and defining characteristic of true fungi.

Common mistake: Students often mistakenly choose option D because they remember that some hyphae have cross-walls (septa), but this is not a universal feature for all fungi, as some important groups are aseptate (lack cross-walls).

The exoskeleton is a tough, waterproof outer covering that acts like a suit of armour for the insect. This shell protects them from enemies and physical damage, and crucially, it prevents them from losing water and drying up. This adaptation allowed insects to successfully colonize dry land and thrive in a wide variety of environments, making them incredibly successful.

Common mistake: Students often mistake option B, which describes the result of being successful (surviving in various conditions), for the actual adaptation (the exoskeleton) that causes that success.

The mosquito undergoes complete metamorphosis, which has four distinct stages: egg, larva, pupa, and adult. The larval stage of the mosquito lives in water and is officially called a wriggler. This name comes from the characteristic wriggling motion it uses to move through the water.

Common mistake: Students often confuse the larval names of different common insects and may incorrectly choose 'maggot', which is the larva of a housefly, not a mosquito.

In a termite colony, there are different groups called castes, each with a special job. The long-winged reproductives, also called alates, are the future kings and queens of new colonies. Their main function is to take part in swarming, which is when they fly out from their home colony in a large group to find mates and start new colonies elsewhere.

Common mistake: Students might choose 'disperse the population' because swarming does lead to dispersal, but 'participate in swarming' is the more precise term for the specific reproductive behaviour of the winged termites.

The question asks for a 'peculiar' characteristic, which means a feature that is unique to mammals. While mammals have teeth, are warm-blooded, and possess lungs, these traits are also found in other animal groups like reptiles or birds. However, the presence of sebaceous glands, which produce oil for the skin and hair, is a distinctive feature found only in mammals.

Common mistake: Students often mistakenly choose 'are warm blooded' because it is a well-known mammalian trait, but they forget that birds are also warm-blooded, so it is not a feature unique to mammals.

The pith is the soft, spongy tissue found in the center of plant stems and roots. In dicotyledonous (dicot) stems, the vascular bundles are arranged in a ring, leaving a large, distinct pith in the middle. Similarly, in monocotyledonous (monocot) roots, there is also a large, well-developed pith at the center, surrounded by the vascular tissues.

Common mistake: Students often mistakenly choose option D because they mix up the internal structures, forgetting that it is monocot stems that lack a distinct pith and dicot roots that have a solid vascular core instead of a wide pith.

The gall bladder is a small organ that stores bile, which is produced by the liver to help digest fats. When needed, the bile is released from the gall bladder through the bile duct. This duct empties directly into the duodenum, which is the first part of the small intestine, allowing the bile to mix with the food coming from the stomach.

Common mistake: Students often mistakenly choose 'liver' because they know the liver produces the bile that the gall bladder stores, confusing the production site with the delivery destination for digestion.