JAMB UTME - Biology - 2014

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Akọwa Nkọwa

Explanation provided by Dr. Deraji

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A poikilothermic organism is an organism whose body temperature changes with the surrounding environment. An example of a poikilothermic organism is a lizard. Lizards cannot regulate their body temperature like humans can, so their body temperature fluctuates with changes in the environment. For example, when it's cold outside, a lizard's body temperature will drop, and when it's hot outside, a lizard's body temperature will rise. This is why you often see lizards basking in the sun on hot rocks or surfaces - they are trying to raise their body temperature.

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The lowest level of organization in living organisms is the cell. A cell is the basic unit of life and is the smallest structure that can perform all the necessary functions for an organism to live. All living things are made up of one or more cells, and each cell has a specific function to perform. Cells can be compared to tiny factories that work together to keep an organism alive and functioning properly. Different types of cells have different structures and functions, but they all share certain characteristics such as the ability to grow, reproduce, respond to stimuli, and maintain homeostasis. Therefore, the cell is the fundamental building block of life and the lowest level of organization in living organisms.

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The sieve tubes and companion cells are present in the phloem. Phloem is the tissue in vascular plants that is responsible for the transport of food (sugar) from the leaves to other parts of the plant. The sieve tubes and companion cells work together to move the food through the plant. The sieve tubes are long, thin cells with porous walls that allow food to flow through them. The companion cells are adjacent to the sieve tubes and help regulate the flow of food by controlling the size of the pores in the sieve tube walls.

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The lowest level of organization in living organisms is the "cell". A cell is the smallest unit of life that can carry out all the functions necessary for an organism to survive. Cells are like tiny factories, each performing its specific job to keep the organism alive. Different types of cells have different structures and functions. For example, red blood cells transport oxygen, nerve cells transmit signals, and muscle cells allow movement. Cells can also group together to form tissues, such as muscle or skin, which perform specific functions. Tissues can then combine to form organs, like the heart or liver, which have more complex functions. Organs work together in organ systems, such as the digestive or respiratory system, to carry out vital processes for the organism's survival. But it all starts with the cell, the basic unit of life.

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The group of organisms that feeds directly on green plants are called "Primary Consumers". Primary consumers are herbivores, which means they eat plants as their main source of food. They are the first level of consumers in the food chain and they rely on the energy and nutrients from plants to survive. For example, a caterpillar that feeds on leaves, a rabbit that grazes on grass, or a deer that browses on shrubs are all examples of primary consumers. These organisms are an important link between the producers (plants) and the rest of the food chain, as they convert the energy and nutrients from plants into forms that can be used by other organisms.

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The growth pattern in plants is described by the statements "Growth is mainly apical" and "Growth is throughout life". "Growth is mainly apical" means that the primary growth of plants occurs at the tips of roots and shoots, where the apical meristem (a group of undifferentiated cells) is located. These cells divide and differentiate to produce new cells, which elongate and become specialized to form different tissues such as the stem, leaves, and roots. This type of growth allows the plant to increase its length and height. "Growth is throughout life" means that plants continue to grow and develop throughout their entire lifespan. While the majority of growth occurs during the early stages of development, plants can continue to grow and produce new cells even in old age. This is in contrast to animals, where growth is typically restricted to a certain period of development. The statement "Growth is specific with definite shape" is not a characteristic of plant growth. While plants do exhibit some degree of morphological and anatomical specificity, their growth is not limited to a predetermined shape. Rather, the shape and form of the plant are the result of various environmental and genetic factors that influence its growth and development.

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In bryophytes, sex organs are produced in the gametophyte. Bryophytes are non-vascular plants that include mosses, liverworts, and hornworts. The gametophyte is the dominant phase of the bryophyte life cycle, and it produces male and female sex organs called antheridia and archegonia, respectively. Antheridia produce male gametes called sperm, while archegonia produce female gametes called eggs. Fertilization occurs when sperm swim through water to reach the archegonia and fertilize the eggs, leading to the production of a sporophyte. The sporophyte is the diploid phase of the life cycle, and it grows out of the gametophyte. It produces spores through meiosis, which are dispersed to new locations to begin new gametophyte generations.

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The concept that all living organisms are constantly involved in a struggle for existence was proposed by Charles Darwin. Charles Darwin was a famous naturalist and biologist who proposed the theory of evolution by natural selection. According to Darwin, all living organisms compete with each other for limited resources such as food, water, and shelter. Those organisms that are better adapted to their environment have a greater chance of surviving and reproducing, passing on their advantageous traits to their offspring. Darwin's theory of natural selection is based on the idea that random genetic mutations occur in living organisms, leading to variations in traits. These variations can either be beneficial, detrimental, or neutral. Organisms with beneficial traits are more likely to survive and reproduce, while those with detrimental traits are less likely to survive and reproduce. Over time, the beneficial traits become more common in a population, and the detrimental traits become less common. In summary, Darwin proposed that all living organisms are constantly involved in a struggle for existence, where only the fittest survive and pass on their advantageous traits to their offspring. This concept is a cornerstone of the theory of evolution by natural selection.

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The biological agent with antiviral properties is Interferon. Interferons are proteins that are naturally produced by cells in response to viral infections. They help to boost the immune system's response to viruses by blocking the ability of viruses to replicate and spread in the body. Interferons can also activate other immune cells to help fight the viral infection. Overall, Interferons are a valuable tool in treating viral infections and are used in various antiviral therapies.

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The study of how and why population size changes over time is called "Population dynamics". It is a branch of ecology that focuses on understanding the factors that affect the size, distribution, and composition of populations of organisms, including humans. Population dynamics involves analyzing changes in population size, birth rates, death rates, immigration, and emigration to gain insights into the factors that influence population growth or decline. By studying population dynamics, ecologists and other scientists can better understand the relationships between organisms and their environment, and develop strategies to manage or conserve populations of species that are important for human well-being or ecosystem health.

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The circulatory system is essential in larger organisms, such as mammals, because their bodies are made up of many cells, and diffusion alone is not sufficient to transport materials to all parts of the body. On the other hand, smaller organisms, like Amoeba, are unicellular, meaning they are made up of only one cell. This allows materials, such as oxygen and nutrients, to diffuse easily across the cell membrane, without the need for a circulatory system. Additionally, Amoeba doesn't require blood containing haemoglobin for oxygen transport, as it absorbs oxygen directly from the surrounding water through its cell membrane. Moreover, as Amoeba doesn't have complex organs and tissues, anaerobic respiration is sufficient to produce energy for its needs. Therefore, Amoeba doesn't require a circulatory system like larger organisms, as diffusion is sufficient to transport materials across its cell membrane.

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The stomata of leaves are similar in function to the spiracles of insects. Stomata are tiny openings or pores found on the surface of leaves and stems of plants. They are responsible for regulating the exchange of gases (such as oxygen and carbon dioxide) between the plant and the environment. During photosynthesis, plants absorb carbon dioxide through the stomata, while releasing oxygen and water vapor. Spiracles are the small openings found on the surface of an insect's exoskeleton. They also serve as a means of gas exchange, allowing for the diffusion of oxygen and carbon dioxide between the insect's body and the environment. Similar to stomata, the opening and closing of spiracles is controlled by specialized cells to help regulate gas exchange and prevent water loss. While the pharynx of humans, the scales of fish, and the trachea of toads are all important structures in their respective organisms, they are not similar in function to the stomata of leaves.

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The nitrogen-fixing blue-green algae of soil is Anabaena. Anabaena is a type of cyanobacteria that is capable of fixing atmospheric nitrogen into a form that plants can use. It forms symbiotic associations with certain plants, such as rice and Azolla ferns, where it provides them with fixed nitrogen in exchange for carbohydrates. Anabaena is commonly found in soil, freshwater, and marine environments, and it is important for maintaining soil fertility and supporting plant growth.

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A severe and long dry season is a characteristic feature of the Sahel Savanna. The Sahel Savanna is a transitional region between the Sahara desert to the north and the more humid savannas to the south, located in West Africa. The region is characterized by a semi-arid climate with a long, severe dry season and a short rainy season. During the dry season, which lasts for several months, there is little to no rainfall, and the region experiences high temperatures and strong winds, leading to drought and water scarcity. The vegetation in the Sahel Savanna is adapted to this dry climate, with sparse grasses and small trees that can survive with limited water. In contrast, Mangrove Swamps are wetland ecosystems found along coastal areas that are characterized by brackish water and tidal movements. Sudan Savanna and Guinea Savanna are savanna regions located to the south of the Sahel Savanna that receive more rainfall and have a less severe dry season.

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The pollutant that is mostly associated with acid rain is nitrogen (IV) oxide, also known as nitrogen dioxide (NO2). When nitrogen oxide is released into the atmosphere, it reacts with other gases to form nitric acid and other acidic compounds. These compounds then fall to the earth's surface as acid rain, which can have harmful effects on the environment, including damaging plant and animal life and corroding buildings and infrastructure. Nitrogen oxide is primarily produced by human activities, such as burning fossil fuels and operating transportation vehicles.

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The part of the brain responsible for peristalsis is the Medulla Oblongata. The Medulla Oblongata is located at the base of the brain stem, and it controls many vital functions such as breathing, heart rate, and digestion. It is responsible for coordinating the contractions of smooth muscles in the digestive tract, which is called peristalsis. Peristalsis is a wave-like movement that pushes food along the digestive tract, allowing for the absorption of nutrients and the elimination of waste. The Medulla Oblongata sends signals to the muscles in the digestive tract to contract and relax in a coordinated manner, which results in peristalsis. So, the Medulla Oblongata plays an important role in the digestive process by controlling peristalsis, which allows us to break down food and absorb nutrients.

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A characteristic feature of tropical rainforest is that it contains a large number of plant species. Tropical rainforests are known for their incredible biodiversity and are home to more plant and animal species than any other biome on Earth. These forests are typically located near the equator, where the climate is warm and humid year-round, providing ideal conditions for plant growth. The high level of rainfall and constant warmth create a diverse range of microclimates within the rainforest, which in turn supports a wide variety of plant life, from towering trees to tiny ferns and mosses. Therefore, the key characteristic of tropical rainforest is its high level of plant species diversity.

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Whorls, arches, loops, and compounds are types of variations in finger prints. Finger prints are unique patterns of ridges and valleys on the fingertips that are used for identification. The four types describe the shape of the ridges in the print. For example, a loop fingerprint has a loop shape, while a whorl has a circular pattern.

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The soil with the highest water-retaining capacity is clayey soil. Clay particles are very small and have a high surface area, which allows them to hold onto water molecules tightly. The spaces between clay particles are also very small, which means water has a harder time escaping the soil once it's absorbed. In contrast, sandy soil has large particles with larger spaces in between them, which means water can easily pass through and drain out. Loamy soil is a mixture of clay, sand, and silt, so it has some water-retaining capacity, but not as much as clayey soil. Stony soil, on the other hand, typically has poor water-retaining capacity since the stones take up space and leave fewer spaces for water to be retained in the soil.

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The cerebellum, located at the base of the brain, is responsible for coordinating movement and balance. It helps to control the smooth and accurate execution of voluntary movements, such as reaching for a glass of water or playing a sport. It also plays a role in maintaining balance and stability, and in some cases, it can even modify movements based on sensory information. In short, the cerebellum helps to regulate muscular activity, but it does not control reflex action, emotional expressions, or the endocrine system.

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The correct term for the use of moist skin for respiration in amphibians is "cutaneous respiration". Cutaneous respiration is a process where the skin of an amphibian absorbs oxygen from the surrounding environment and releases carbon dioxide, allowing the amphibian to breathe. This type of respiration is especially important for amphibians that live in water or in environments with low oxygen levels, as it helps them to supplement their respiratory system and stay alive. In simple terms, cutaneous respiration is a way for amphibians to breathe through their skin.

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The alternation of generation is a feature shown in mosses and some other plants, but not in fungi or grasses or conifers. Alternation of generation refers to a life cycle where an organism alternates between a multicellular diploid (2n) phase called the sporophyte, and a multicellular haploid (n) phase called the gametophyte. In mosses, the sporophyte is a stalk-like structure that grows out of the gametophyte and produces spores, while the gametophyte is a small leafy structure that produces gametes. The spores produced by the sporophyte develop into a new gametophyte, completing the life cycle. In fungi, there is no alternation of generation. Most fungi have a haploid-dominant life cycle, meaning that they spend most of their life cycle in the haploid phase. They produce haploid spores that can grow into new haploid individuals, without the need for a diploid phase. In grasses and conifers, the life cycle is dominated by the diploid sporophyte phase, with the haploid gametophyte phase being reduced to small structures that produce gametes. These gametes fuse to form a diploid zygote, which develops into a new sporophyte. So, in summary, mosses exhibit alternation of generation, while fungi, grasses, and conifers do not.

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Binary fission and conjugation are two different processes of reproduction in single-celled organisms. Binary fission is a simple type of asexual reproduction in which a single cell divides into two daughter cells. On the other hand, conjugation is a type of sexual reproduction that occurs in some single-celled organisms, including the protozoan Paramecium. In Paramecium, when the cells reach a certain level of maturity or stress, they may engage in conjugation instead of binary fission. During conjugation, two Paramecium cells temporarily join together and exchange genetic material. This process allows for genetic diversity and can help the organisms adapt to changing environments. So to answer the question, when the adults have reached a certain degree of weakness, the process of binary fission is replaced by conjugation in Paramecium.

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Smallpox is a highly infectious and deadly disease caused by the variola virus. It is not caused by bacteria, but by a virus. Antibiotics are not effective against viruses, so smallpox cannot be controlled with antibiotics. However, vaccination is an effective way to prevent the spread of smallpox. The smallpox vaccine was developed in the late 18th century and has been used to successfully eradicate smallpox globally. The vaccine works by introducing a weakened form of the virus into the body, which triggers an immune response and provides immunity against the disease. Smallpox is not a water-borne infection. It is spread through the air by respiratory droplets or by direct contact with an infected person's bodily fluids or contaminated objects such as bedding or clothing.

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A barometer is used for measuring atmospheric pressure. It works by measuring the weight of the atmosphere pressing down on a surface and is typically used to predict changes in weather. A barometer can be either an aneroid barometer, which uses a sealed chamber to measure pressure changes, or a mercury barometer, which uses a column of mercury to measure pressure changes. Both types of barometers provide a simple and comprehensive way to measure atmospheric pressure in a way that is easy to understand.

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The situation can be explained by the fact that the sex of a baby is determined by the combination of sex chromosomes from both parents. Typically, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). Since the couple has 10 female children, it means that the father has been consistently passing on his X chromosome to all his offspring instead of the Y chromosome. This is not an unusual occurrence and is purely a matter of chance. Therefore, the best explanation for this situation would be "The sex determination was by the man's X chromosome." The other options are not relevant to the situation as there is no evidence to suggest that the man's sperm count is low, the woman is incapable of producing male children, or the sex determination was by the man's Y chromosome.

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The genetic make-up of an organism is described as its genotype. Genotype refers to the complete set of genes and genetic material that an organism inherits from its parents. This includes both the dominant and recessive genes, and determines the genetic traits and characteristics of the organism. For example, a person's genotype determines things like their eye color, hair color, and height, as well as their susceptibility to certain diseases or conditions. While some genetic traits may be visible, such as eye color or hair color, many others are not visible to the naked eye. Allele refers to a variant form of a gene that codes for a specific trait. Chromosomes are structures that contain DNA and are located in the nucleus of a cell. Phenotype refers to the observable physical or biochemical traits of an organism, which are determined by both the genotype and environmental factors.

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The streamlined shape of fishes is an adaptation for easy movement through water. The long and narrow body of fishes reduces water resistance, making it easier for them to swim and move quickly through the water. This shape also allows them to make quick turns and changes in direction, which helps them escape from predators and catch their prey. Additionally, the streamlined shape reduces the amount of energy required for swimming, allowing fishes to swim for longer periods without getting tired. Therefore, the streamlined shape of fishes is primarily an adaptation for efficient swimming and movement in their aquatic environment.

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An arboreal organism is an organism that lives in trees. Out of the options listed, the bird is the only arboreal organism, as birds can live and build their nests in trees. Elephants are terrestrial (land-dwelling) animals, fish live in water, and antelopes are also terrestrial animals that live on the ground.

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Explanation provided by Dr. Deraji

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An individual with blood group AB can receive blood from donors who have any blood group. This is because individuals with blood group AB have both A and B antigens on the surface of their red blood cells, making them compatible with all other blood groups. On the other hand, people with blood group O are universal donors, as their red blood cells do not have A or B antigens and can be transfused to individuals with any blood group.

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The causative agent of Poliomyelitis is a virus. Poliomyelitis, also known as polio, is an infectious disease caused by a virus called the poliovirus. This virus primarily affects the nervous system and can lead to paralysis, muscle weakness, and even death. The virus is spread from person to person, usually through contaminated food or water. The other options, Fungus, Protozoan, and Bacterium, are not the cause of Poliomyelitis.

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The constituent of the exhaust fumes from electricity generating sets which causes serious pollution is Carbon Dioxide (CO2). CO2 is a colorless and odorless gas that is released when fossil fuels like coal, oil, and natural gas are burned to generate electricity. While it is a naturally occurring gas, the burning of fossil fuels has caused a significant increase in the amount of CO2 in the atmosphere, leading to a phenomenon known as global warming and climate change. This increase in CO2 levels has caused the Earth's average temperature to rise, leading to changes in weather patterns, melting of polar ice caps, and rising sea levels. These changes are having a profound impact on the planet and its inhabitants, making it crucial for us to reduce our carbon footprint and transition to cleaner, renewable sources of energy.

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The correct answer is "transpiration." Transpiration is the process by which water in plants is removed as water vapor. It occurs when water is drawn up from the roots and moves through the plant's tissues to the leaves. Once the water reaches the leaves, it evaporates and exits the plant as water vapor through tiny pores on the surface of the leaves called stomata. Think of it like sweating in humans. When we sweat, water is drawn from our bodies and evaporates from our skin, cooling us down. Similarly, when plants transpire, water is drawn from the plant and evaporates from the leaves, helping to cool the plant down and maintain its temperature. Transpiration is an important process for plants because it helps to transport nutrients throughout the plant, maintain the plant's structure, and regulate its temperature. It also plays a role in the water cycle by releasing water vapor into the atmosphere, which can eventually condense and form precipitation.

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An example of an organ of perennation in plants is a rhizome. Perennation refers to the survival of a plant from one growing season to another. Rhizomes are specialized underground stems that grow horizontally, producing roots and shoots at intervals. They serve as a food storage organ and also help plants survive adverse environmental conditions. During unfavorable conditions such as drought or extreme temperatures, the above-ground parts of the plant may die back, but the rhizome can remain dormant until conditions improve. When the environment becomes favorable again, the rhizome can sprout new shoots and leaves, allowing the plant to continue growing. Seeds can also serve as organs of perennation, allowing plants to survive through unfavorable conditions, but they are not considered examples of organs of perennation since they are not a part of the plant itself. Petals and calyx of flowers are not organs of perennation because they are involved in reproduction and not survival from one growing season to another.

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The influence of soil on organisms in a habitat is referred to as "edaphic". Edaphic factors include soil pH, texture, moisture content, and nutrient availability, among others, all of which can affect the growth and survival of plants and other organisms. For example, some plants may require well-drained soil, while others may thrive in soil that retains more moisture. The presence of certain nutrients in the soil may also be essential for the growth of specific organisms. In short, edaphic factors are critical components of any habitat and play a significant role in shaping the ecosystem.

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Coordination and regulation of body activities in mammals is achieved by both nerves and hormones. Nerves are a part of the nervous system and work by sending electrical signals, or impulses, between the brain and other parts of the body. This allows for rapid communication and control of muscle movement, sensation, and other functions. Hormones, on the other hand, are chemical messengers produced by glands in the endocrine system. They are transported in the bloodstream and help to regulate processes such as growth, metabolism, and reproductive functions. Hormones act more slowly than nerves but can have long-lasting effects. Together, nerves and hormones work to maintain the balance and stability of the body, allowing it to respond to changes in the environment and carry out daily activities.