JAMB UTME - Biology - 2020

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The villi in the small intestine are significant because they increase the surface area for absorption. The small intestine is where most of the nutrients from digested food are absorbed into the bloodstream. The villi are small, finger-like projections on the inner wall of the small intestine that increase the surface area available for absorption. By increasing the surface area, the villi allow for a greater amount of nutrients to be absorbed in a shorter amount of time, thus increasing the efficiency of the digestive process.

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When bacteria swim from cold to warm regions, this is known as positive thermotaxis. Thermotaxis refers to the movement of organisms in response to changes in temperature. Positive thermotaxis means that the bacteria are attracted to warmer temperatures, so they swim from cold regions to warm regions. This behavior is thought to be an adaptation that allows bacteria to find environments that are optimal for growth and survival.

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Epiphytes growing on the branches of trees provide an example of the relationship known as commensalism. Commensalism is a type of symbiotic relationship in which one species benefits from the relationship, while the other species is neither helped nor harmed. In the case of epiphytes, they benefit from growing on the branches of trees by receiving support and access to light, while the trees are neither helped nor harmed by the presence of the epiphytes. In contrast, parasitism is a type of symbiotic relationship in which one species benefits at the expense of the other species, saprophytism is a type of symbiotic relationship in which one species benefits by consuming dead organic matter, and holophytism is a type of symbiotic relationship in which both species benefit by exchanging resources and nutrients.

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The butterfly is of great economic importance because it pollinates flowers of crops and other plants. This means that it helps in the fertilization of these plants, which is an essential step in their growth and reproduction. As a result, these crops can produce more fruits and vegetables, which can then be used for food, medicine, and other products. This ultimately helps to support agriculture and the overall economy. Additionally, by pollinating flowers, the butterfly also helps to maintain the balance of the ecosystem and preserve biodiversity.

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Fish have the most simple structured heart among the listed vertebrates. In fish, the heart is typically composed of two chambers: the atrium, which receives blood, and the ventricle, which pumps blood out to the gills and the rest of the body. This simple structure is sufficient for the needs of fish, which have a relatively low metabolic rate and a simple circulatory system. In comparison, reptiles, mammals, and amphibians have more complex hearts with additional chambers and more sophisticated circulatory systems to support their higher metabolic demands. For example, reptiles have a three-chambered heart with two atria and one ventricle, while mammals and birds have a four-chambered heart with two atria and two ventricles, which helps to separate oxygenated and deoxygenated blood.

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External fertilization takes place in amphibians, such as toads. External fertilization is a method of reproduction where the sperm and egg cells are fertilized outside of the female's body. This is different from internal fertilization, where the sperm and egg are fertilized inside the female's body. In the case of toads, the male will release his sperm into the water and the female will release her eggs, where they will meet and fertilize outside of the body. Other species, like birds, lizards, and cockroaches, typically have internal fertilization.

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The probability of a baby being a boy or a girl depends on the contribution of the father's and mother's sex cells. The father contributes a sperm cell, which can be either X (female) or Y (male) chromosome. The mother contributes an egg cell, which is always X chromosome. When the sperm fertilizes the egg, the combination of X and Y chromosomes determine the gender of the baby. If the sperm carries an X chromosome, the baby will be female (XX). If the sperm carries a Y chromosome, the baby will be male (XY).

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For growth to occur in organisms, the rate of anabolism must exceed that of catabolism. Anabolism is the process by which cells build up complex molecules, such as proteins and carbohydrates, from simpler precursors. Catabolism, on the other hand, is the process by which cells break down complex molecules into simpler components to release energy. In order for growth to occur, the rate of anabolism must be greater than the rate of catabolism, meaning that the organism is synthesizing more new material than it is breaking down. If catabolism exceeds anabolism, the organism will break down more material than it can replace, leading to a net loss of mass. Food storage levels do not directly impact growth, as growth can occur in organisms with both high and low food storage levels. In summary, for growth to occur in organisms, the rate of anabolism must exceed that of catabolism, regardless of food storage levels.

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In frogs, the skin functions as a respiratory surface. Frogs have moist, permeable skin that allows for gas exchange, meaning they can take in oxygen and release carbon dioxide through their skin. This is particularly important for frogs because they spend much of their time in water, where they are less able to obtain oxygen through their lungs. The skin on their underside is especially well adapted for this function and is often covered in tiny bumps, called papillae, which increase the surface area available for gas exchange. In contrast, rats, lizards, and fish do not use their skin as a respiratory surface. These animals have specialized respiratory systems, such as lungs or gills, that are specifically designed to exchange gases and support their respiratory needs.

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The term used to describe biotic and abiotic factors in the environment of an organism is "ecosystem". An ecosystem is a community of living and non-living things that interact with each other in a specific environment. Biotic factors are the living components of an ecosystem, such as plants, animals, and microorganisms. Abiotic factors are the non-living components, such as soil, water, temperature, light, and air. The way that these factors interact with each other in a particular ecosystem determines the unique characteristics of that ecosystem and the types of organisms that can survive there.

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A group of organisms of different species living in a particular area is described as a community. A community refers to the interaction and interdependence of different species living in a specific location. It includes all the different populations of organisms, such as plants, animals, and microbes, that live and interact with each other in a particular ecosystem. In contrast, a population refers to a group of individuals of the same species living in a specific area, while a niche refers to the role or position a species holds within an ecosystem, including the resources it uses and the functions it performs. A colony, on the other hand, refers to a group of individuals of the same species that live together and are physiologically connected, such as a colony of ants or a colony of coral.

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The function of ribosomes in cells is protein synthesis. Ribosomes are the cellular structures that are responsible for making proteins. They do this by reading the instructions encoded in messenger RNA molecules and assembling the appropriate sequence of amino acids to form a protein. This process is called translation and is a crucial step in the overall process of protein synthesis. Starch synthesis, transport of material, and lipid storage are not functions of ribosomes. These processes are carried out by different cellular structures and enzymes. Starch synthesis, for example, is carried out by specialized enzymes in the cytoplasm. Transport of material is carried out by specialized structures such as the endoplasmic reticulum, Golgi apparatus, and vesicles. Lipid storage is carried out by structures such as lipid droplets.

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The waste product in plants that is excreted through the stomata and lenticles is carbon dioxide. Plants take in carbon dioxide through the stomata and lenticles during the process of photosynthesis, where it is used as a source of carbon to make food. The oxygen produced during photosynthesis is released back into the air through the stomata and lenticles, while the excess carbon dioxide is excreted. This helps regulate the plant's internal carbon dioxide levels and maintain a healthy balance of gases in the plant's cells. On the other hand, alkaloids, tannins, and anthocyanins are all compounds produced by plants, but they are not excreted through the stomata and lenticles. Instead, they serve various functions in the plant, such as protecting it from predators and disease, attracting pollinators, and providing color and flavor to fruits and flowers.

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The noticeable adaptation of an animal to its aquatic habitat is the possession of webbed digits. Webbed digits are the fusion of the toes of an animal, giving them a wider surface area to help them swim through the water more efficiently. Animals that live in aquatic environments, such as ducks and otters, have webbed digits that allow them to swim and navigate through their habitats with greater ease. This adaptation is an example of how animals can evolve to better suit their environments and improve their chances of survival.

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The ability of the eyes to focus on both near and distant objects is called accommodation. Accommodation is the process by which the eyes adjust their focus to allow us to see objects clearly, whether they are close or far away. This is achieved through the action of the ciliary muscles and the crystalline lens inside the eye. When we look at a nearby object, the ciliary muscles contract, causing the lens to become thicker and more curved. This change in shape helps to bring the image of the object into focus on the retina. When we look at a distant object, the ciliary muscles relax, causing the lens to become flatter, which helps to focus the image of the distant object onto the retina. Image formation, refraction, and hypermetropia are related to the function of the eye, but they are not the same as accommodation. Image formation refers to the process by which light is transformed into an electrical signal that can be interpreted by the brain. Refraction refers to the bending of light as it passes through the cornea and lens to form an image on the retina. Hypermetropia is a type of refractive error in which the eye has difficulty focusing on nearby objects.

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The only caste in a termite colony whose members can feed themselves are the workers. Workers are responsible for foraging for food and bringing it back to the colony to feed the other members of the colony, including the reproductives, soldiers, and nymphs. The reproductives, soldiers, and nymphs are unable to feed themselves and rely on the workers for sustenance. The workers have specialized mouthparts that allow them to chew and process food, while the other castes have mouthparts that are not well-suited for feeding.

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In a population of living things, the parameters of size, height, weight, and color are examples of continuous variation. Continuous variation refers to the presence of a range of traits within a population, where individuals exhibit a spectrum of variation rather than distinct, separate categories. For example, height, weight, and size are continuously varying traits, with no clear-cut boundaries between individuals who are tall, short, heavy, or light. Similarly, color in many species, such as fur color in mammals, is a continuously varying trait, with no clear boundaries between individuals who are brown, black, or white. These traits are determined by multiple genes and can be influenced by environmental factors, leading to a wide range of variation within a population.

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The biological association that contributes directly to succession in a community is competition. Succession is the process of change and development in a community of organisms over time. Competition is the interaction between individuals or populations of different species that results in the exclusion of one or more species from the community. As species compete for resources such as light, water, and nutrients, some species may become dominant and others may become less abundant or disappear. This change in the composition of the community can lead to succession, as the dominant species create new microhabitats and provide resources for other species, ultimately leading to the development of a mature and diverse community. In contrast, predation is the interaction between a predator and its prey, parasitism is a type of symbiotic relationship in which one species benefits at the expense of the other species, and commensalism is a type of symbiotic relationship in which one species benefits from the relationship, while the other species is neither helped nor harmed.

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In an agricultural ecosystem, the biotic component consists of crops, pests, and beneficial insects. The biotic component of an ecosystem refers to all the living things that are present in the environment, including plants, animals, and microorganisms. In an agricultural ecosystem, crops are the main focus of attention as they are grown for human consumption or for use as animal feed. Pests, such as insects and diseases, can damage crops and reduce yields, while beneficial insects, such as pollinators and predators, help to maintain a healthy ecosystem by controlling pests and pollinating crops. So, the biotic component of an agricultural ecosystem includes crops, pests, and beneficial insects.

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Walking is controlled by the cerebellum, which is located in the brainstem at the base of the brain. The cerebellum is responsible for coordinating movement, balance, and coordination. It receives information from the muscles and joints about the body's position and movement, and then sends signals to other parts of the brain and the spinal cord to make adjustments and ensure smooth, coordinated movement. This is why the cerebellum plays a crucial role in the process of walking.

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The bright colors of the comb and feathers in the peacock are for courtship. Peacocks use their colorful and distinctive feathers as a way to attract mates during the breeding season. The vibrant colors and intricate patterns of the feathers are meant to display the male peacock's health, strength, and fitness to potential mates. This display of colorful feathers is part of the courtship behavior of peacocks and is meant to attract a female for mating. The bright colors are not directly related to sex differentiation, beauty, or defence.

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The hormone that regulates the amount of glucose in the blood is insulin. Insulin is a hormone produced by the pancreas, an organ located near the stomach. Its main function is to regulate the levels of glucose, or sugar, in the blood. When we eat, our blood glucose levels rise and the pancreas releases insulin to help move glucose from the bloodstream into the cells, where it can be used for energy. Insulin also helps store excess glucose in the liver and muscle tissue for later use. By regulating the levels of glucose in the blood, insulin helps maintain overall health and prevent conditions such as diabetes, which can occur when insulin production is disrupted. Adrenaline, auxin, and thyroxine are other hormones in the body that serve different functions, but do not regulate glucose levels in the blood. Adrenaline is a hormone involved in the fight-or-flight response and helps increase heart rate, breathing, and blood flow. Auxin is a hormone involved in plant growth and helps regulate the elongation of cells and the formation of roots and shoots. Thyroxine is a hormone produced by the thyroid gland and helps regulate metabolism, or the process by which the body converts food into energy.

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The most accurate way to resolve paternity disputes is through DNA Analysis. DNA Analysis is a scientific method that compares a person's genetic material to determine if there is a biological relationship. This method works by looking at specific regions of a person's DNA that are inherited from their parents. By comparing the DNA of a child with that of the alleged father, it is possible to determine with a high degree of accuracy whether the man is the biological father of the child. This method is widely used in legal and medical contexts to resolve paternity disputes, as it provides a clear and reliable answer.

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The process you are referring to is called hemolysis. Hemolysis is when a red blood cell, which normally contains a high concentration of dissolved substances such as hemoglobin, bursts due to an increase in fluid pressure. This can occur when the cell is placed in a solution with a lower concentration of dissolved substances, such as distilled water. The water moves into the cell, causing it to swell and eventually burst. In contrast, osmosis is the diffusion of water molecules from an area of high concentration to an area of low concentration through a semi-permeable membrane. Plasmolysis is the shrinking of a plant cell due to water loss through osmosis. Turgidity is the normal, healthy state of a plant cell where it is swollen due to the absorption of water.

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The hypha of Rhizopus is said to be non-septate because it does not have cross walls, also known as septa. In fungi, septa are walls that divide the hypha into individual cells. However, in Rhizopus, the hyphae do not have septa, meaning that the hyphae are continuous and not divided into separate cells. This allows for more efficient transport of nutrients and waste products within the hyphae, which can help the fungus to grow and spread.

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A child who is phenotypically short and born of two tall parents can be explained by the presence of genes for shortness in both parents. Our physical characteristics, such as height, are determined by a combination of genes inherited from both parents. Just because a parent is tall doesn't mean they don't carry genes for shortness. When two carriers of the gene for shortness have a child, there is a chance that the child will inherit two copies of the gene and express the short phenotype. This is an example of how dominant and recessive genes can interact and result in a phenotype that is different from the parents.

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The smallest living organism that shares characteristics of both living and non-living matter is a virus. Viruses are unique in that they cannot reproduce on their own and must infect a living host cell in order to replicate. While they contain genetic material, they lack many of the other characteristics typically associated with living organisms, such as the ability to independently carry out metabolic processes. Bacteria, fungi, and protozoa are all examples of true living organisms that have the ability to independently carry out metabolic processes and reproduce. They are typically larger in size than viruses and have a more complex structure. In summary, the smallest living organism that shares characteristics of both living and non-living matter is a virus, while bacteria, fungi, and protozoa are true living organisms with more complex structures and abilities.

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The excretory structure in earthworms is the nephridium. A nephridium is a tubular structure that is responsible for removing waste products from the body of an earthworm. It works similarly to a kidney in other organisms and helps to maintain the balance of water and other substances in the earthworm's body.

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Floating microscopic heterotrophs are mostly grouped as zooplankton. Heterotrophs are organisms that cannot produce their own food and must consume other organisms for sustenance. Zooplankton are small, floating organisms that play an important role in the aquatic food chain, serving as a food source for larger aquatic animals such as fish. Zooplankton can be either microscopic or macroscopic, and they can include a variety of different types of organisms, including small crustaceans, mollusks, and some types of algae. In contrast, phytoplankton are microscopic, photosynthetic organisms that form the base of the aquatic food chain, producing energy through photosynthesis and serving as a food source for zooplankton and other organisms.

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A microscope is not used in measuring abiotic factors in any habitat. Abiotic factors are physical and chemical components of an ecosystem that are not created by living organisms. These include temperature, light, moisture, wind, and soil characteristics. Instruments such as a thermometer, hygrometer, and windvane are used to measure abiotic factors like temperature, moisture, and wind direction. However, a microscope is an instrument used to magnify and examine small, living or non-living, objects and is not commonly used to directly measure abiotic factors in a habitat. In summary, a microscope is not used to measure abiotic factors in a habitat, while instruments like a thermometer, hygrometer, and windvane are commonly used for this purpose.

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The vertebra illustrated is likely a thoracic vertebra. Thoracic vertebrae are the middle bones in the spinal column and are located in the chest region. They are distinguishable by the characteristic spinous process (bony bump) on the back and the two small facets on the sides that allow the rib bones to attach to them. These vertebrae play a crucial role in protecting the spinal cord and allowing for movement of the upper body.

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Deamination occurs in the liver. Deamination is a process where an amino acid is broken down into a simpler molecule by removing its amino group (-NH2). This process is important because it helps to release nitrogen from amino acids, which can then be used to make other important compounds in the body, such as urea. The liver plays a key role in this process because it is responsible for removing excess nitrogen from the body, and deamination is one of the ways it accomplishes this.