JAMB UTME - Biology - 2007

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A biotic factor that affects the distribution and abundance of organisms in a terrestrial habitat is competition. Competition occurs when two or more individuals or populations try to use the same limited resource, such as food, water, or shelter. In a given habitat, there may be multiple species competing for resources, and the outcome of this competition can have a significant impact on the distribution and abundance of each species. For example, if two species have overlapping ranges and compete for the same food source, one species may outcompete the other and drive it to a different location or even cause it to become extinct in the area. Competition can also occur within a species, such as when members of the same population compete for limited resources. This can lead to changes in the distribution and abundance of individuals within that population, as those that are better suited to acquiring the limited resources are more likely to survive and reproduce. While temperature, pH, and light can also affect the distribution and abundance of organisms in a terrestrial habitat, these are considered abiotic factors, as they are non-living components of the environment.

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The highest level of ecological organization is the biosphere. The biosphere includes all living things on Earth, including all ecosystems and their interactions with each other. Essentially, the biosphere is the sum of all the planet's ecosystems, and it is the highest level because it encompasses the entire Earth and all the living things that inhabit it. The biosphere is a complex and dynamic system, and understanding how it works is essential for understanding the health and well-being of our planet.

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The mangrove swamp in Nigeria is restricted to the tropical rainforest. The mangrove swamps are found in the coastal regions of Nigeria and are characterized by the presence of mangrove trees. These trees are adapted to live in the brackish waters of the coastal regions, where saltwater and freshwater mix. The tropical rainforest region of Nigeria is located in the southern part of the country, along the coast. It is characterized by high rainfall and dense vegetation, including the mangrove trees in the coastal areas. The other regions mentioned - Sahel savanna, Sudan savanna, and Guinea savanna - are all located in the northern part of Nigeria and are characterized by grasslands, trees, and shrubs adapted to the drier conditions of the region.

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The organs that will be most useful to giant African rats in finding their way in underground habitats are their vibrissae or whiskers. These whiskers are long, stiff hairs located on their faces that are highly sensitive to touch and can detect changes in air currents and vibrations in the ground. By using their whiskers, giant African rats can create a mental map of their surroundings, including detecting obstacles, changes in the terrain, and the presence of prey or predators. Their nostrils are also important for detecting smells, but their sense of sight is not as useful in underground environments where light is limited. Their tails do not play a significant role in navigation, but they can help with balance and communication with other rats.

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The earthworm uses diffusion as the principal method of gaseous exchange. Earthworms are terrestrial invertebrates that breathe through their skin, which is thin, moist, and permeable to gases. As they move through the soil, oxygen from the air diffuses through their skin and into their bloodstream, while carbon dioxide and other waste gases diffuse out of their bodies and into the surrounding environment. This process of gas exchange is called diffusion, which is the passive movement of gases from an area of high concentration to an area of low concentration. Therefore, the earthworm is the organism that uses diffusion as the principal method of gaseous exchange.

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The characteristic that is common to the mosquito, housefly, and blackfly is that their immature stages are aquatic. Mosquitoes, houseflies, and blackflies all undergo a four-stage life cycle that includes an egg, larva, pupa, and adult stage. During the larval stage, these insects live in water and feed on organic matter, such as algae or detritus. Mosquito larvae live in standing water, while blackfly larvae live in flowing water. Housefly larvae, also known as maggots, can be found in a variety of moist organic material, including decaying plant matter and animal waste. After completing their larval stage, the insects undergo metamorphosis and develop into their adult form. Mosquitoes, houseflies, and blackflies all have two pairs of wings, and they are all important vectors of disease. However, the other options presented are not true for all three of these insects.

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The structure labelled l in the diagram is the pituitary gland, which is a major endocrine gland in the body. The function of the pituitary gland is to regulate the activities of other endocrine glands, including the thyroid gland, the adrenal glands, and the ovaries or testes. The pituitary gland produces several hormones that control the secretion of hormones from these other glands. For example, the pituitary gland produces thyroid-stimulating hormone (TSH), which stimulates the thyroid gland to produce thyroid hormones. It also produces adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to produce cortisol, a hormone that helps the body to cope with stress. The pituitary gland also produces follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which are involved in the development of secondary sexual characteristics and the regulation of the reproductive system. Therefore, the correct answer is that the function of the structure labelled l is to regulate the activities of other endocrine glands.

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None of its offspring will be born without a tail. The presence or absence of tails in dogs is a trait that is controlled by a single gene, with the dominant allele (T) producing tails, and the recessive allele (t) producing no tails. The diagram shows that dog II is heterozygous for this gene, meaning it carries one copy of the dominant allele and one copy of the recessive allele (Tt), and dog III is homozygous recessive (tt). When dog II mates with dog III, their offspring will inherit one allele from each parent. The Punnett square below shows the possible genotypes and phenotypes of their offspring: | | T | t | |---|---|---| | t | Tt| tt| | t | Tt| tt| As you can see from the Punnett square, all of the offspring will inherit one copy of the dominant T allele from dog II, and therefore they will all have tails. However, since dog II is heterozygous, 50% of the offspring will carry the recessive t allele, even though they have tails. If two of these tail-carrying offspring were to mate in the future, they could produce some offspring without tails. Therefore, none of the offspring from the mating of dog II and dog III will be born without tails, but some of them will carry the recessive allele for taillessness and could produce tailless offspring in the future if they mate with another carrier.

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The pancreas is a gland located in the abdomen and has both exocrine and endocrine functions. Its exocrine function is to secrete digestive enzymes into the small intestine for the breakdown of nutrients. The enzymes secreted by the pancreas include pancreatic amylase for the digestion of carbohydrates, pancreatic lipase for the digestion of fats and pancreatic proteases for the digestion of proteins. Therefore, the correct answer is "fats, proteins and carbohydrates".

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A water medium is necessary for fertilization in ferns. Fertilization is the process by which male and female gametes combine to form a zygote, which develops into a new individual. In ferns, the male gametes are produced in the antheridia and the female gametes are produced in the archegonia. In order for fertilization to occur, the male gametes need to swim through a water medium to reach the female gametes, which are protected inside the archegonia. This is why ferns require a water medium, such as rain or dew, for their reproduction. Fungi, conifers, and angiosperms do not require a water medium for fertilization. Fungi reproduce asexually or sexually through the fusion of hyphae, the thread-like structures that make up their body. Conifers and angiosperms are both seed-producing plants that use pollen to transfer male gametes to female gametes. The pollen is carried by wind or animals, such as bees or birds, and does not require a water medium for fertilization.

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The chromosomes of members of the kingdom Monera are within the cytoplasm. Monera is a kingdom of organisms that includes bacteria and cyanobacteria, which are single-celled and prokaryotic, meaning they do not have a nucleus. Instead, their genetic material, or chromosomes, are found within the cytoplasm, which is the jelly-like substance that fills the cell. In other words, the chromosomes in Monera are not separated from the rest of the cell by a nuclear membrane, as is the case in eukaryotic cells. Therefore, the chromosomes of Monera are located in the cytoplasm of the cell.

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The theory which supports the view that the large muscles developed by an athlete will be passed on to the offspring was proposed by Lamarck. Lamarck proposed a theory of inheritance of acquired characteristics which suggests that traits acquired by an individual during its lifetime can be passed on to its offspring. According to Lamarck, if an athlete develops large muscles through intense exercise, then those muscles will become larger and stronger during the athlete's lifetime. Lamarck suggested that these acquired traits could then be passed on to the athlete's offspring, allowing them to also have larger and stronger muscles. However, this theory has been largely discredited by modern genetics, which suggests that traits are primarily determined by an individual's genetic makeup, rather than their environment or experiences.

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The process of shedding the exoskeleton of an arthropod is known as ecdysis. Ecdysis, also known as molting, is a natural process that allows arthropods to grow. The exoskeleton of arthropods, such as insects, spiders, and crustaceans, is made of a tough, protective material called chitin. However, this exoskeleton does not grow with the animal. Therefore, arthropods must periodically shed their old exoskeleton and replace it with a new one. This process is called ecdysis, and it allows the arthropod to grow and develop. During ecdysis, the old exoskeleton splits open, and the arthropod crawls out. The new exoskeleton is soft at first but hardens over time, providing protection and support for the arthropod's body.

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The breeding posture illustrated in the diagram is known as "amplexus." Amplexus is a mating behavior commonly observed in amphibians, where the male grasps the female from behind with his front legs, while she lays eggs. This allows the male to fertilize the eggs as they are being released. Amplexus can be further categorized into two types: axillary amplexus and inguinal amplexus, depending on where the male grasps the female.

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One example of a fish that aestivates is the lungfish. Aestivation is a state of reduced activity and metabolic rate that some animals use as a way to survive during periods of high temperatures and low water availability. Lungfish are found in tropical and subtropical regions where the water can evaporate during the dry season, leaving behind isolated pools with limited resources. In response, lungfish can aestivate by burrowing into the mud at the bottom of the pool, secreting a mucus cocoon around themselves, and slowing down their metabolism to survive for months without food or water until the rainy season returns. Sharks, croakers, and catfish are not known to aestivate. Sharks are adapted to survive in a wide range of temperatures and environments, including cold and warm water. Croakers and catfish are freshwater fish that can tolerate a wide range of temperatures and water conditions, but they do not have the ability to aestivate.

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Monocot stems differ from dicot stems in that monocot stems have no cambium. The cambium is a layer of tissue in dicot stems that is responsible for producing new vascular tissue, allowing the plant to grow in diameter. Monocots, on the other hand, have scattered vascular bundles throughout the stem, which are not produced by cambium. This is one of the key differences between monocot and dicot stems.

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In mammals, the organ directly on top of the kidney is the adrenal gland. The adrenal gland is a small, triangular-shaped gland that is located on top of each kidney. It is an important endocrine gland that produces hormones such as adrenaline, cortisol, and aldosterone, which play important roles in regulating the body's response to stress, maintaining blood pressure, and controlling the balance of salt and water in the body.

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The type of protective adaptation exhibited by the animal in the diagram is countershading colouration. Countershading is a type of protective coloration that helps to camouflage an animal by using different colors on the upper and lower parts of the body. The darker color on the upper part of the body helps to blend in with the shadows and darker areas of the environment, while the lighter color on the lower part of the body helps to blend in with the brighter areas. This makes it more difficult for predators to detect the animal, as it appears to blend in with the surrounding environment. In the diagram, the animal has a darker color on its back and a lighter color on its belly, which is typical of countershading. This type of adaptation is common in many animals, including sharks, penguins, and deer. It is especially useful for animals that need to hide from predators or prey, as it helps to break up the outline of the body and make the animal less visible.

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The waste product of plants used in the conversion of hide to leather is tannin. Tannins are a type of astringent and bitter-tasting organic compounds that are found in various parts of plants, including leaves, bark, and fruit. They are commonly used in the production of leather from animal hides. During the process of tanning, the hide is treated with tannins, which bind to the collagen fibers and other proteins in the hide, making it more durable and resistant to decay. Tannins are also used to give leather its characteristic color and texture. Tannins can be obtained from a variety of plant sources, including oak bark, chestnut bark, and mimosa bark. These plant materials are boiled in water to extract the tannins, which are then used in the tanning process. In summary, tannin is the waste product of plants that is commonly used in the conversion of hide to leather. It is a type of organic compound found in various parts of plants and is used to bind to the collagen fibers in animal hides to make leather more durable and resistant to decay.

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In lizards, the lowering of the gular fold is used to attract mates. The gular fold is a flap of skin located on the throat of lizards. During courtship, males will lower their gular fold and display it to females as a form of visual communication. This display is often accompanied by head-bobbing, color changes, and other behaviors. The gular fold is an important part of courtship behavior in many lizard species, and is used to signal the male's availability and fitness to potential mates.

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An accurate identification of a rapist can be carried out by conducting a DNA analysis. DNA analysis involves comparing the DNA of the suspect with the DNA evidence collected at the crime scene, such as semen or saliva. If the DNA profiles match, it provides strong evidence that the suspect was present at the crime scene and could be the perpetrator of the crime. DNA is unique to each individual, except in the case of identical twins, making it a highly reliable method for identifying suspects. On the other hand, RNA analysis is not typically used for forensic identification because RNA is not as stable as DNA and is more difficult to isolate and analyze. Blood group typing can provide some limited information, but it is not as reliable as DNA analysis since many people can share the same blood group. Behavioural traits tests, such as polygraph tests, are also not reliable for forensic identification since they are not accurate enough to provide definitive evidence of guilt or innocence.

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The part labeled IV is responsible for osmoregulation. Osmoregulation is the process by which an organism regulates the concentration of water and solutes in its body fluids in order to maintain homeostasis. In aquatic animals like fish, osmoregulation is especially important because they are constantly surrounded by water that may have a different concentration of solutes than their body fluids. The part labeled IV in the diagram is the kidney, which is the primary organ responsible for osmoregulation in vertebrates. The kidney filters waste products and excess ions from the blood, while also reabsorbing essential molecules and regulating the balance of water and electrolytes in the body. Therefore, the kidney plays a crucial role in maintaining proper osmotic balance in the body. Respiration, ingestion, and locomotion are not directly related to the part labeled IV in the diagram.

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Cloning involves creating an organism with the same genetic material as the original organism. One way to clone an organism is by taking a somatic cell (any non-reproductive cell in the body) and transferring its nucleus to an egg cell that has had its nucleus removed. This new cell is then stimulated to develop into an embryo, which can be implanted in a surrogate mother to develop into a cloned organism. It is not necessarily true that cloning is welcomed as an ethical and morally sound science, as there are many ethical and social concerns surrounding cloning, particularly in the context of cloning humans. It is true that only one cell of the original organism is needed to initiate the cloning process, as this cell contains all the genetic information necessary to create a new organism. The clone is similar to but not exactly like the original organism, as environmental factors can play a role in shaping an organism's development and behavior, in addition to genetic factors. Finally, cloning does involve the asexual multiplication of the tissues of the original organism, as the new organism is essentially a genetic copy of the original organism.

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An example of a sex-linked trait is the possession of facial hair in adult humans. Sex-linked traits are traits that are determined by genes located on the sex chromosomes (X and Y chromosomes). In humans, the gene for the ability to grow facial hair is located on the Y chromosome, which is present only in males. This means that the ability to grow facial hair is inherited from the father to the son and is not expressed in females, who have two X chromosomes. The other traits mentioned - ability to grow long hair in females, colour of the skin in humans, and ability to roll the tongue - are not sex-linked traits but rather are determined by other genes or a combination of genes and environmental factors.

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In the diagram, the part marked I will contain a high concentration of auxin. Auxin is a plant hormone that plays a variety of roles in plant growth and development, including promoting cell elongation, regulating apical dominance, and initiating the formation of roots. The part marked I in the diagram is the tip of a plant shoot, which is the site of active cell division and growth. Auxin is produced in the tip of the shoot, and then transported downward through the plant to the roots. This means that the concentration of auxin is highest in the tip of the shoot, which is where the hormone is synthesized. Ascorbic acid, abscisic acid, and ethylene are also plant hormones, but they are not primarily associated with the tip of the shoot or with promoting cell elongation.

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Pineapple is an example of a composite fruit. A composite fruit is a fruit that develops from a cluster of flowers called an inflorescence. In the case of pineapple, the fruit develops from the fusion of many small individual fruits called fruitlets, which are arranged in a spiral pattern around the central core of the fruit. Each fruitlet contains a seed and is covered by a fleshy, edible layer that is derived from the ovary wall of the flower. Other examples of composite fruits include figs and mulberries. Composite fruits are different from simple fruits, which develop from a single ovary, and aggregate fruits, which develop from many separate ovaries in a single flower. Dehiscent fruits, on the other hand, are fruits that split open at maturity to release their seeds, such as legumes and capsules.

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The causative agent of bird flu is a virus. Specifically, it is an influenza virus that primarily affects birds, but can also infect humans and other animals. The virus is classified as a type A influenza virus and is further divided into subtypes based on the proteins on its surface, including H5N1 and H7N9. The virus is transmitted through contact with infected birds, their saliva, nasal secretions, or feces. In humans, bird flu can cause a range of symptoms, from mild to severe, including fever, cough, and difficulty breathing. In some cases, it can lead to severe respiratory illness, pneumonia, and even death. It is important to note that while the virus is primarily a concern for birds, it can occasionally infect humans, particularly those who work with birds or live in close proximity to them.