JAMB UTME - Biology - 2005

Maelezo ya Majibu

Maelezo ya Majibu

The sperm cell is likely to have a higher concentration of the mitochondria. Mitochondria are organelles responsible for producing energy in cells, and the sperm cell requires a lot of energy to swim and reach the egg for fertilization. Therefore, to meet this high energy demand, the sperm cell needs a high concentration of mitochondria. On the other hand, white blood cells and red blood cells have lower energy demands, while the egg cell is relatively large and contains yolk, which provides energy for early embryonic development, so they do not require as many mitochondria as sperm cells.

Maelezo ya Majibu

The transition from amphibians to mammals involved the evolution of limbs that were arranged to support the weight of the animal more effectively. This required modifications in the pectoral and pelvic girdles. The pectoral and pelvic girdles are the bones that connect the limbs to the axial skeleton, and they provide support for the entire body. In mammals, the pectoral and pelvic girdles became more robust and were modified to provide a stronger attachment for the limbs. This allowed mammals to support their weight on land and to move more efficiently. The collar bones and coccyx, scapulae and clavicles, and vertebrae and sternum are also important bones, but they were not the primary focus of modification in the transition from amphibians to mammals.

Maelezo ya Majibu

The bile is stored in the part labelled II. The diagram is showing the human digestive system and the part labelled II is the gallbladder. The gallbladder stores and releases bile, which is a digestive fluid produced by the liver. When food reaches the small intestine, the gallbladder contracts and releases bile into the small intestine to aid in the digestion of fats.

Maelezo ya Majibu

The blackfly is a vector of onchocerciasis, also known as river blindness. A vector is an organism, such as a mosquito or fly, that transmits a disease-causing organism, such as a parasite or virus, from one host to another. In the case of the blackfly, it can transmit a parasite called Onchocerca volvulus, which can cause severe itching, skin lesions, and eventually blindness if left untreated. Onchocerciasis is a serious disease that affects millions of people in Africa, Latin America, and Yemen, and the blackfly is one of its primary vectors.

Maelezo ya Majibu

Maelezo ya Majibu

The main function of the caudal fin in Tilapia is to propel it forward in water. The caudal fin is the tail fin of a fish, and it is responsible for generating the propulsion that moves the fish through water. In Tilapia, the caudal fin is particularly large and powerful, which allows the fish to swim efficiently and maneuver through its aquatic environment. The other fins, such as the pectoral and dorsal fins, help to control the direction of movement and maintain balance, but it is the caudal fin that provides the primary means of propulsion for Tilapia.

Maelezo ya Majibu

The white trait is said to exhibit recessiveness. When a yellow maize (which has the dominant yellow trait) is crossed with a white maize (which has the recessive white trait), the resulting first filial generation will only show the dominant yellow trait because it masks the expression of the recessive white trait. However, the recessive trait is still present in the genetic makeup of the plants, and may appear in future generations if certain conditions are met. This is because the recessive trait only shows when two copies of the recessive gene are present in the genotype.

Maelezo ya Majibu

The pericardium is a fluid-filled sac that surrounds and protects the heart. Its main function is to reduce friction and cushion the heart as it contracts and relaxes during each heartbeat. Essentially, it acts as a shock absorber for the heart, preventing damage from the friction caused by the movement of the heart. Therefore, the correct option is: "reduce the friction caused by the pumping movements of the heart".

Maelezo ya Majibu

Maelezo ya Majibu

Bacteria swimming from cold to warm regions is known as positive thermotaxis. This means that the bacteria are attracted to warmer temperatures and will move towards them. Bacteria use different types of taxis, such as chemotaxis and phototaxis, to move towards or away from different stimuli in their environment. In this case, the warm temperature acts as a stimulus that the bacteria are moving towards, which is why it is called positive thermotaxis.

Maelezo ya Majibu

The mammalian lung is made air tight by the pleural membrane. The pleural membrane is a thin, double-layered membrane that covers the lungs and lines the inside of the chest cavity. It creates a sealed, air-tight space around the lungs called the pleural cavity, which helps to maintain the pressure gradient necessary for breathing. The pleural membrane also produces a lubricating fluid that reduces friction and allows the lungs to expand and contract smoothly during breathing. Therefore, it is the pleural membrane that makes the mammalian lung air tight.

Maelezo ya Majibu

The hyphal wall of fungi is rigid owing to the presence of chitin. Chitin is a tough, protective, and semi-transparent polysaccharide that makes up the exoskeletons of insects and crustaceans, as well as the cell walls of fungi. It is made up of long chains of a modified sugar called N-acetylglucosamine, which form a tough, fibrous structure that provides support and protection to the fungal cell. The presence of chitin in the hyphal wall gives it its characteristic rigidity.

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

The evidence of a common ancestor for fishes, amphibians, reptiles, birds and mammals is the presence of gill clefts in vertebrate embryos. All vertebrate embryos at some point during development have gill slits, which are openings in the neck region that eventually develop into various structures in different species. This is evidence of a shared ancestry because it indicates that these organisms share a common developmental pathway that has been modified over time through evolution to produce the diverse range of adult forms seen in these groups. Possession of wings by birds and bats, cold-bloodedness of fishes, amphibians, and reptiles, and possession of scales by fish and reptiles are all characteristics that have evolved independently in these groups and are not unique to their common ancestor.

Maelezo ya Majibu

Secondary succession is usually much quicker than primary succession for the following reasons:

There is already an existing seed bank of suitable plants in the soil.

Root systems undisturbed in the soil, stumps and other plant parts from previously existing plants can rapidly regenerate.

The fertility and structure of the soil has also already been substantially modified by previous organisms to make it more suitable for growth and colonization.

Maelezo ya Majibu

The Mambila plateau is a unique Nigerian biome located in Taraba state.

Maelezo ya Majibu

The recycling method of solid waste disposal is unsuitable for organic matter. This is because organic matter can decompose over time and turn into compost, which is a valuable soil conditioner. However, glass, plastic, and metal scraps can be recycled and used again, which reduces the amount of waste that ends up in landfills or incinerators. Therefore, the recycling method is not suitable for organic matter, but it is suitable for glass, plastic, and metal scraps.

Maelezo ya Majibu

The members in the termite colony that can feed themselves are the workers. Workers are a caste of termites that are responsible for foraging for food, building and maintaining the nest, and caring for the other members of the colony. They are the only caste that can feed themselves, as they have well-developed mandibles and can digest cellulose, the main component of wood, which is a common food source for termites. The other castes, such as the reproductives, nymphs, and soldiers, rely on the workers to feed them.

Maelezo ya Majibu

The stage in the life history of a moth responsible for the destruction of agricultural crops is the caterpillar. Caterpillars are the larval stage of moths and butterflies, and they are known for their voracious appetite for plant matter. They have strong mandibles that allow them to chew through leaves, stems, and other plant parts, which can result in significant damage to crops. Once the caterpillar has completed its feeding stage, it will pupate and eventually emerge as an adult moth.

Maelezo ya Majibu

Maelezo ya Majibu

Angiosperms and gymnosperms belong to the class Spermatophyta. Spermatophyta is a group of plants that reproduce by producing seeds. This class includes two major divisions, gymnosperms and angiosperms. Gymnosperms are plants that have seeds without any protective covering or fruit, while angiosperms are plants that have seeds enclosed in a fruit. Both of these divisions are further divided into various families and species.

Maelezo ya Majibu

Maelezo ya Majibu

The leech and the earthworm both belong to the phylum Annelida. Annelids are segmented worms with a body that is divided into many small, repeating units. They have a closed circulatory system, a digestive system, and a nervous system. The leech and the earthworm are both hermaphrodites, which means they have both male and female reproductive organs. They play an important role in maintaining soil health and are often used as bait for fishing.

Maelezo ya Majibu

Maelezo ya Majibu

When a peacock displays its colourful feathers, it is courting a female. The elaborate display of feathers is a mating ritual that serves to attract the attention of female peahens. The peacock will fan out his feathers and perform a dance while making a loud calling sound. The brighter and more vibrant the feathers, the more attractive the peacock is to the female. The display of feathers is a way for the peacock to demonstrate his fitness as a mate and to compete with other males for the attention of the females.

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

Maelezo ya Majibu

Hydrostatic skeleton is the type of supporting system found in oligochaetes and some other invertebrates like cnidarians and flatworms. In this type of skeleton, the body is supported by a fluid-filled cavity, which acts as a hydrostatic skeleton. The muscles of the body wall contract against the fluid, generating a pressure that supports the body and provides the necessary rigidity for movement. The oligochaetes, which are a type of annelid worms, use hydrostatic skeletons to burrow in soil and move through water.

Maelezo ya Majibu

The adaptation described in the question is called countershading. Countershading is a form of camouflage in which the upper part of an animal's body is darkly colored while the lower part is light-colored. This adaptation helps to conceal the animal from predators or prey by breaking up its outline and making it more difficult to see. The dark dorsal surface blends in with the dark background above, while the light ventral surface blends in with the brighter background below, making the animal appear more uniform in color and therefore harder to detect.

Maelezo ya Majibu

From the question, it seems to be referring to the water cycle, where water moves through various stages, including evaporation, condensation, precipitation, and storage in different reservoirs. The question is asking about the main reservoir of water in this cycle. Out of the options given, the ocean is the largest and most significant reservoir of water in the water cycle. It holds about 97% of the Earth's water, making it the most significant water body on the planet. It plays a crucial role in the water cycle, as it's the primary source of water for the cycle. Water from the ocean evaporates, forming water vapor that rises into the atmosphere, and then it returns to the earth as precipitation, completing the water cycle. Therefore, the correct answer to the question is "ocean."

Maelezo ya Majibu

Maelezo ya Majibu

Shivering in a cold environment is a homostatic response in humans. Homostasis is the ability of the body to maintain a stable internal environment, despite external changes. Shivering is a mechanism that helps the body maintain its internal temperature in a cold environment by generating heat through muscle contractions. This is an example of a homostatic response, as it helps to maintain the body's internal temperature within a normal range. The other options are not examples of homostatic responses. Withdrawing the hand from a hot object is a reflex action to protect the body from injury. The mouth getting watery when food is sighted is a digestive response. Yawning due to tiredness is a physiological response, but not homostatic.

Maelezo ya Majibu

The vein that carries pure oxygenated blood is the pulmonary vein. The pulmonary vein is the only vein in the body that carries oxygenated blood from the lungs to the heart. The other veins in the body carry deoxygenated blood back to the heart. The renal vein carries blood from the kidney to the heart, the hepatic vein carries blood from the liver to the heart, and the sciatic vein does not exist (there is a sciatic nerve, but no sciatic vein).

Maelezo ya Majibu

An example of a radially symmetric organism is Hydra. Radial symmetry is a type of symmetry where the body of the organism can be divided into identical halves by any plane passing through its central axis. In the case of Hydra, it has a tubular body with tentacles around its mouth that can be extended and retracted in any direction, giving it radial symmetry. Other examples of radially symmetric organisms include jellyfish, sea anemones, and starfish.

Maelezo ya Majibu

If a child is phenotypically short and both parents are tall, the most likely explanation is that both parents carry a recessive gene for shortness. When both parents are heterozygous for a recessive trait, there is a 25% chance that their child will inherit two copies of the recessive allele and express the trait. In this case, the trait is shortness. Therefore, it is most likely that both parents possess the gene for shortness, but it is only expressed in the child because they inherited two copies of the recessive allele.

Maelezo ya Majibu

Crop rotation is an agricultural practice of planting different crops in the same field in successive seasons to maximize yields and maintain soil health. The importance of practicing crop rotation is to maintain soil fertility. Planting the same crop in the same field season after season can cause the depletion of certain nutrients in the soil, leading to reduced yields and poor crop quality. Crop rotation helps to balance soil fertility by allowing the soil to recover and replenish nutrients that were used up by the previous crop. This can improve soil structure, reduce soil erosion, and enhance the growth of subsequent crops. Additionally, crop rotation can help to control pests and diseases that may attack a specific crop by breaking their life cycles and reducing their population in the soil.

Maelezo ya Majibu

A non-renewable alternative source of energy is nuclear energy. Nuclear energy is obtained through the fission of uranium atoms in a process that produces heat, which is used to generate electricity. While it is an alternative to traditional fossil fuels, such as oil and coal, which are also non-renewable, nuclear energy is also controversial due to concerns about safety and the disposal of radioactive waste.

Maelezo ya Majibu

The order of evolutionary advancement of the above vertebrates can be explained as follows: Rattus rattus is a species of rodent, which belongs to the class Mammalia. Mammals are generally considered to be more evolutionarily advanced than other vertebrates such as reptiles, amphibians and fish. Agama agama is a species of lizard, which belongs to the class Reptilia. Reptiles are considered less evolutionarily advanced than mammals, but more advanced than amphibians and fish. Bufo regularis is a species of toad, which belongs to the class Amphibia. Amphibians are considered less evolutionarily advanced than reptiles and mammals, but more advanced than fish. Tilapia zilli is a species of fish, which belongs to the class Actinopterygii. Fish are generally considered to be the least evolutionarily advanced of the vertebrates. Therefore, the order of evolutionary advancement from the above vertebrates is: I, II, III, IV

Maelezo ya Majibu

The urinary tubules of the kidney function through ultrafiltration and selective reabsorption. The process of ultrafiltration involves the movement of small molecules, such as water and ions, from the blood in the glomerulus into the renal tubules. This is driven by the pressure of the blood in the glomerulus and results in the formation of a filtrate that contains water, ions, and other small molecules. Selective reabsorption then takes place in the renal tubules, where some of the substances that were filtered out of the blood during ultrafiltration are reabsorbed back into the bloodstream. This process is selective because only certain substances, such as glucose, amino acids, and ions, are reabsorbed, while other substances, such as urea and excess water, are left behind in the tubules to be excreted as urine. Therefore, the correct answer is ultrafiltration and selective reabsorption.

Maelezo ya Majibu

To calculate the population size of Tridex on the farm, we need to know the total area of the farm land. Since the farm land is square and has a side length of 200 m, the area is given by the formula: Area = Side length x Side length Area = 200 m x 200 m Area = 40,000 m2 Now, we know that the population density of Tridex is 5 plants per m2. To find the population size, we need to multiply the population density by the total area of the farm: Population size = Population density x Area Population size = 5 plants/m2 x 40,000 m2 Population size = 200,000 plants Therefore, the population size of Tridex on the farm is 200,000. Option (d) is the correct answer.

Maelezo ya Majibu

Excess water in plants is removed through a process called transpiration, where water vapour is released through tiny pores called stomata on the leaves. In some plants, excess water can also be removed through guttation, where droplets of water are excreted through special structures called hydathodes. Therefore, the correct answer is "transpiration and guttation".

Maelezo ya Majibu

Cockroaches are ectothermic animals, meaning their body temperature is regulated by the surrounding environment. They are known to thrive in warm environments, with some species preferring temperatures above 30oC. Studies have shown that cockroaches exposed to temperatures below their lower thermal limits can lead to death. Therefore, the temperature at which cockroaches will not survive after 10 days will depend on the temperature being lower than their lower thermal limit. From the given options, the lowest temperature is 15oC, which is lower than the lower thermal limit for most species of cockroaches. Hence, 15oC is the most likely option for the temperature at which cockroaches will not survive after 10 days.

Maelezo ya Majibu

When two organisms interact, and one benefits from the interaction while the other is not affected in either a positive or negative way, this type of association is called commensalism. In other words, one organism is "commensal" with the other, meaning that it is sharing the same space and resources without causing harm or benefit to the other organism. An example of commensalism is when a bird builds its nest on a tree, which doesn't harm the tree, but the bird benefits by having a place to raise its young.

Maelezo ya Majibu

Maelezo ya Majibu

The correct answer is HCl(aq). When HCl(aq) is added to a soil sample containing lime, a reaction occurs that produces carbon dioxide gas. The presence of carbon dioxide gas indicates the presence of lime in the soil sample. Therefore, HCl(aq) is used to test for the presence of lime in a soil sample.

Maelezo ya Majibu