JAMB UTME - Biology - 2013
Pregunta 1 Informe
The main structure in vertebrates that supports and protects the body is the
Detalles de la respuesta
The main structure in vertebrates that supports and protects the body is the skeleton. The skeleton is a framework of bones that provides support for the body and protects vital organs such as the heart, lungs, and brain. It also provides a place for muscles to attach, allowing for movement and flexibility. The skeleton is an essential part of the body and plays a crucial role in maintaining its shape, stability, and overall health.
Pregunta 2 Informe
The process in which complex substances are broken down into simpler ones is referred to as
Detalles de la respuesta
The process in which complex substances are broken down into simpler ones is referred to as "catabolism". Catabolism is a type of metabolic process that breaks down large molecules (such as carbohydrates, proteins, and fats) into smaller molecules (such as glucose, amino acids, and fatty acids) to release energy that the body can use for various functions. Think of it as like breaking down a big puzzle into smaller pieces, which can then be used to create something else. For example, when you eat food, your body breaks it down through catabolism into simpler molecules that can be used for energy, growth, and repair.
Pregunta 3 Informe
Which blood cell are involved in the immune response of vertebrates?
Detalles de la respuesta
Lymphocytes are the blood cells involved in the immune response of vertebrates. They are white blood cells that play a crucial role in protecting the body from infections and diseases. Lymphocytes have the ability to recognize and remember specific invaders, such as bacteria, viruses, and other harmful substances. When they encounter these invaders, they respond by producing and releasing special proteins called antibodies, which help to neutralize the invaders and prevent them from causing harm. In addition to producing antibodies, lymphocytes can also directly attack and destroy infected cells. They do this by recognizing and targeting cells that have been taken over by viruses or other invaders. Overall, lymphocytes play a vital role in the body's defense against diseases and infections, helping to keep us healthy and protected.
Pregunta 4 Informe
The clumping together of red blood cells is
Detalles de la respuesta
The clumping together of red blood cells is called agglutination. It occurs when antibodies in the plasma of one blood type bind to the antigens on the surface of another blood type's red blood cells, causing them to stick together and form clumps. This process is part of the body's immune response, as it helps to identify and attack foreign substances in the bloodstream. However, if it occurs during a blood transfusion or in the case of incompatible blood types, it can lead to serious complications such as organ damage or even death. Therefore, blood compatibility is an important consideration in medical procedures that involve the transfer of blood or blood products.
Pregunta 5 Informe
A plant tissue that carries water and mineral salts is the
Detalles de la respuesta
The plant tissue that carries water and mineral salts is called xylem. Xylem is like the plant's plumbing system, it's responsible for transporting water and nutrients from the roots to the rest of the plant, including the leaves. The water and nutrients move through tiny tubes called xylem vessels, which are made up of special cells that are long and narrow, with thick walls to prevent collapsing under pressure. These cells are also dead at maturity, which allows them to form a continuous pipeline without any interruptions. Overall, the xylem plays a crucial role in keeping the plant hydrated and providing it with the necessary nutrients for growth and development.
Pregunta 6 Informe
Movement of minerals and chemical compounds with a plant occurs during
Detalles de la respuesta
Movement of minerals and chemical compounds within a plant occurs during translocation. Translocation is the process by which organic compounds, nutrients, and hormones are transported throughout the plant from the site of production to the site of utilization or storage. This process occurs in the phloem tissue, which is responsible for the movement of organic compounds such as sugars, amino acids, and hormones. During translocation, organic compounds are actively transported from source tissues (such as leaves and storage organs) to sink tissues (such as growing roots, fruits, and flowers) through specialized cells called sieve tubes. This transport occurs through a pressure gradient, with the source tissues creating a high pressure and the sink tissues creating a low pressure, which pushes the organic compounds through the phloem tissue. Translocation is vital for plant growth and development, as it enables the movement of nutrients and hormones to where they are needed most. Without translocation, plants would not be able to survive or thrive, as they would be unable to transport vital nutrients and hormones throughout the plant.
Pregunta 7 Informe
The solid part of the ecosystem is referred to as the
Detalles de la respuesta
The solid part of the ecosystem is referred to as the lithosphere. The lithosphere includes the Earth's crust and the uppermost part of the mantle, and it is the layer that supports all life on Earth. It is made up of rocks, minerals, and soils that provide the foundation for all terrestrial life. The lithosphere interacts with the other components of the ecosystem, such as the atmosphere, hydrosphere, and biosphere, through various physical, chemical, and biological processes. Together, these components make up the Earth's ecosystem, which sustains life on our planet.
Pregunta 8 Informe
Which of the following distinguishes a butterfly from a moth?
Detalles de la respuesta
Butterflies usually rest with their wings closed, while moths rest with their wings open. Butterflies have long, thin antenna, while moths have shorter feathery antennas.
Pregunta 9 Informe
The absence of anti-diuretic hormone in humans results in
Detalles de la respuesta
The absence of anti-diuretic hormone (ADH) in humans results in increasing dehydration. ADH is a hormone produced by the pituitary gland in the brain that helps regulate the body's water balance by controlling the amount of water that is reabsorbed by the kidneys. When ADH is absent, the kidneys do not reabsorb enough water from the urine, which leads to an increase in urine output and a decrease in the amount of water in the body. As a result, the body becomes dehydrated, which can lead to symptoms such as thirst, dry mouth, fatigue, and dizziness. So, in summary, the absence of ADH in humans results in increasing dehydration, as the kidneys excrete too much water, leading to a decrease in the overall amount of water in the body.
Pregunta 10 Informe
The sensory cell that responds to dim light is referred to as the
Detalles de la respuesta
The sensory cell that responds to dim light is called a "rod." Rods are one of two types of light-sensitive cells in the retina of the eye, the other being "cones." While cones are responsible for color vision and work best in bright light conditions, rods are more sensitive to light and help us see in low-light conditions, such as at night. The high concentration of rods in the peripheral areas of the retina is why we often use our side vision to see in the dark.
Pregunta 11 Informe
During the manufacture of food by plants, which of the following organism use energy from the sun?
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Pregunta 12 Informe
Which of the following is a waste product of an insect?
Detalles de la respuesta
The waste product of an insect is uric acid. Insects, like all animals, need to get rid of waste products produced by their bodies. Insects do not have kidneys like humans, so they cannot excrete waste in the form of urine. Instead, they excrete waste in the form of solid uric acid crystals. These crystals are formed from the breakdown of nitrogenous waste products produced during the insect's metabolic processes. The uric acid crystals are then excreted from the insect's body through special structures called Malpighian tubules, which are located in the insect's digestive system. Therefore, uric acid is the waste product of an insect.
Pregunta 13 Informe
A pollutant that is biodegradable is
Detalles de la respuesta
A pollutant that is biodegradable is sewage. Biodegradable means that a substance can be broken down into smaller, simpler compounds by natural processes, such as the action of microorganisms like bacteria or fungi. Sewage, which is a mixture of human and animal waste, is biodegradable because it contains organic matter that can be decomposed by microorganisms. Crude oil and heavy metals are not biodegradable pollutants. Crude oil is a complex mixture of hydrocarbons that can persist in the environment for a long time and is difficult to break down naturally. Heavy metals, such as lead and mercury, are also persistent in the environment and can accumulate in living organisms, causing harm to ecosystems and human health. Cellophane is a man-made material that is generally not biodegradable. It is made from cellulose, a natural polymer found in plant cell walls, but it is treated with chemicals to make it waterproof and resistant to degradation. Cellophane can persist in the environment for a long time, contributing to plastic pollution.
Pregunta 14 Informe
The chitin in the exoskeleton of many arthropods is strengthened by
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Pregunta 15 Informe
The eye defect cause by the development of cloudy areas in the lenses is
Detalles de la respuesta
The eye defect caused by the development of cloudy areas in the lenses is cataract. A cataract is a condition where the natural lens in the eye becomes cloudy, leading to blurred vision, difficulty seeing in dim light, and glare. It usually occurs as a result of aging, but can also be caused by factors such as genetics, injury, or certain medical conditions. Cataracts can be corrected with surgery, where the cloudy lens is replaced with an artificial one, resulting in improved vision.
Pregunta 16 Informe
The process in which complex substances are broken down into simpler ones is referred to as
Detalles de la respuesta
The process in which complex substances are broken down into simpler ones is referred to as catabolism. Catabolism is a metabolic process that breaks down complex molecules such as carbohydrates, fats, and proteins into smaller, simpler units such as glucose, fatty acids, and amino acids. This process releases energy that can be used by cells for various activities such as growth, repair, and movement. Catabolism is essential for the proper functioning of living organisms as it helps to provide energy and raw materials for anabolism, the opposite process that builds complex substances from simpler ones. In addition, catabolism also helps to remove waste products from cells, which can be toxic if they accumulate. In contrast, anabolism is the metabolic process that builds complex molecules from simpler ones, and metabolism is the sum of all the chemical reactions that occur in living organisms. Tropism refers to the response of a plant or animal to external stimuli such as light or gravity.
Pregunta 17 Informe
The special pigment for colour change in chameleon is
Detalles de la respuesta
The special pigment for color change in a chameleon is chromatophore. Chromatophores are specialized cells found in the skin of many animals, including chameleons, that can change color rapidly to help the animal blend into its surroundings or communicate with others of its species. Chromatophores contain different pigments, including melanin and carotenoids, which can be controlled by muscles to expand or contract and change the color and pattern of the animal's skin. For example, when a chameleon wants to blend in with green leaves, it will expand the green pigment-containing chromatophores, and when it wants to appear darker to regulate body temperature, it will expand the black chromatophores. This ability to change color is a remarkable adaptation that helps chameleons avoid predators and attract mates, and it's all thanks to the unique and specialized cells called chromatophores.
Pregunta 18 Informe
The behavioural adaptation in social insects could best be described as
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Cause eveyone in the colony or hive get to do work that will benefit everyone
Pregunta 20 Informe
Fungi are referred to as hetotrophs because they
Detalles de la respuesta
Fungi are referred to as heterotrophs because they cannot make their own food like plants do. They do not have chlorophyll, which is the pigment that allows plants to produce their own food through photosynthesis. Instead, fungi obtain their nutrients by absorbing them from other organisms, dead or alive. This process is known as heterotrophy. The fungal body, known as mycelium, consists of a network of filaments that helps them to break down and absorb nutrients from their surroundings. Fungi do not have roots, but they may have structures called rhizoids that function similarly to roots.
Pregunta 22 Informe
Which of the following forms about 55% of the volume of the blood in man?
Detalles de la respuesta
The component of the blood in humans that forms about 55% of its volume is plasma. Plasma is the yellowish fluid part of the blood that carries nutrients, hormones, waste products, and other substances throughout the body. It also helps regulate the body's pH, temperature, and fluid balance. Plasma is made up of water, proteins, and other dissolved substances, and it plays an important role in maintaining the overall health of the body.
Pregunta 23 Informe
The organ which is sensitive to light in Euglena is the
Detalles de la respuesta
The organ in Euglena that is sensitive to light is called the eyespot. The eyespot is a small, red-colored, pigmented area located near the base of the flagellum in Euglena. It contains a light-sensitive pigment that helps the organism detect the intensity and direction of light. This allows Euglena to move towards light for photosynthesis, and to avoid intense light that can damage its chloroplasts. Think of it like a tiny eye for Euglena that helps it navigate and survive in its environment!
Pregunta 24 Informe
The part of the mammalian skin involved in excretion is the
Detalles de la respuesta
The part of the mammalian skin involved in excretion is the sweat glands. The sweat glands are small structures found in the skin that produce sweat. This sweat helps regulate the body temperature and also helps in removing waste products and toxins from the body through the process of sweating. In this way, the sweat glands play an important role in excretion.
Pregunta 25 Informe
The gland that is found just below the hypothalamus is the
Detalles de la respuesta
The gland that is found just below the hypothalamus is the pituitary gland. The pituitary gland is a small, pea-sized gland located at the base of the brain, beneath the hypothalamus. It is often referred to as the "master gland" because it produces and releases hormones that control the functions of many other glands in the body. The pituitary gland has two main parts: the anterior pituitary and the posterior pituitary, which release different hormones that regulate growth, reproduction, metabolism, and other bodily functions.
Pregunta 26 Informe
The most important plant hormone is
Detalles de la respuesta
The most important plant hormone is auxin. Auxins are plant hormones that play a crucial role in a variety of plant processes, including growth and development, phototropism, gravitropism, apical dominance, and root development. Auxins are produced in the apical meristem of plants and are transported downwards through the plant, where they regulate cell division and elongation. This hormone also promotes the growth of lateral buds and suppresses the growth of lower buds, allowing the plant to grow taller and compete for sunlight. Additionally, auxin is responsible for phototropism, which is the plant's ability to bend towards light. This is particularly important for plants growing in shaded areas, as they need to bend towards light to maximize photosynthesis. Overall, auxin is the most important plant hormone because it controls many vital aspects of plant growth and development, including cell division, elongation, phototropism, and lateral bud growth.
Pregunta 27 Informe
The plants that grow in deserts or very dry areas are referred to as
Detalles de la respuesta
The plants that grow in deserts or very dry areas are referred to as xerophytes. Xerophytes are adapted to survive in environments with limited water availability, high temperatures, and high levels of sunlight. These plants have a variety of adaptations such as long roots to reach water deep underground, small leaves to reduce water loss, and waxy coatings to prevent evaporation. These adaptations allow xerophytes to thrive in arid and desert climates where other plants cannot survive.
Pregunta 28 Informe
One of adaptation of Cactus opuntia to conserve water is the reduction of
Detalles de la respuesta
Pregunta 29 Informe
Oestrogen is a hormone that is synthesized in the
Detalles de la respuesta
Oestrogen is a hormone that is synthesized in the ovaries. The ovaries are two small, almond-shaped organs located in the female reproductive system. They are responsible for producing and releasing eggs, as well as several important hormones, including oestrogen. Oestrogen plays a key role in regulating many aspects of female reproductive and sexual function. It helps to control the menstrual cycle, regulate the growth and development of the reproductive system, and maintain bone density and overall health. Oestrogen levels can fluctuate throughout a woman's life, with levels increasing during puberty and declining after menopause. The decline in oestrogen levels during menopause can result in a range of symptoms, including hot flashes, night sweats, and vaginal dryness. Overall, oestrogen is an important hormone for female health and reproductive function, and it is synthesized and produced by the ovaries.
Pregunta 30 Informe
An example of a parasitic protozoan is
Detalles de la respuesta
One example of a parasitic protozoan is Plasmodium. Plasmodium is a type of protozoan that causes malaria in humans. It is transmitted to humans through the bite of an infected female Anopheles mosquito. Once inside the human body, the Plasmodium parasites multiply in the liver and red blood cells, causing the symptoms of malaria, such as fever, chills, and fatigue. If left untreated, malaria can lead to serious complications and even death.
Pregunta 31 Informe
Which of the following structure is adapted for feeding in a bird of prey?
Detalles de la respuesta
The structure adapted for feeding in a bird of prey is a hooked beak and sharp claws. This is because birds of prey, such as eagles, hawks, and owls, are hunters and use their sharp beaks and claws to catch and kill their prey. The hooked beak helps them to tear apart their food, while the sharp claws allow them to grip and hold onto their prey. This combination of features makes it easier for the bird of prey to feed efficiently and effectively.
Pregunta 32 Informe
The male reproductive organ of a flower is the
Detalles de la respuesta
The male reproductive organ of a flower is called the stamen. The stamen is made up of two main parts: the anther and the filament. The anther is the part of the stamen that produces pollen, which contains the male reproductive cells called sperm. The filament is the stalk-like part that holds up the anther. When a flower is pollinated, the pollen from the anther can travel to the female reproductive part of another flower, called the stigma, where it can fertilize the female reproductive cells called eggs. This process is how plants reproduce and create new seeds to grow into new plants. In summary, the stamen is the male reproductive organ of a flower, and it consists of the anther and filament. The anther produces pollen containing sperm, which can fertilize the female reproductive cells and create new seeds.
Pregunta 33 Informe
Which of the following is the simplest living organism?
Detalles de la respuesta
Among the given options, the simplest living organism is a virus. Viruses are tiny, infectious agents that are not technically alive because they cannot replicate or carry out metabolic activities without a host cell. They consist of a genetic material (DNA or RNA) enclosed within a protein coat, known as a capsid. Some viruses also have an additional outer envelope made of lipids. Viruses rely on host cells to replicate and reproduce, hijacking the cell's machinery to make copies of themselves. Once inside a host cell, the virus injects its genetic material and takes over the cell's metabolism to produce new virus particles. These particles can then infect other cells and continue the cycle of infection. In contrast, the other options, such as Paramecium, Amoeba, and Chlamydomonas, are all considered unicellular organisms because they are made up of a single cell and have the ability to carry out metabolic activities and reproduce on their own. They also have more complex structures and mechanisms than viruses, such as organelles and a range of cellular processes.
Pregunta 34 Informe
To which blood group do universal recipients belong?
Detalles de la respuesta
Universal recipients belong to blood group AB. Blood groups are classified based on the presence or absence of certain antigens on the surface of red blood cells. These antigens can trigger an immune response if they are not compatible with a person's blood type. Blood group AB has both A and B antigens on the surface of their red blood cells, but does not have antibodies against either A or B antigens in their plasma. This means that they can receive red blood cells from any blood type (A, B, AB, or O) without triggering an immune response, making them universal recipients. However, blood group AB individuals can only donate blood to other AB individuals, as their blood contains both A and B antigens.
Pregunta 35 Informe
Proboscis is a structure that is mostly found in
Detalles de la respuesta
Proboscis is a structure that is mostly found in insects. A proboscis is a tubular mouthpart that is used for feeding, sucking up liquids, or probing. It is a long, thin, and flexible appendage that is located on the head of the insect. Some insects, such as butterflies, moths, and mosquitoes, have a proboscis that they use to extract nectar from flowers or blood from animals. Other insects, such as flies, use their proboscis to feed on decaying matter or to lay eggs. In contrast, tapeworms, amphibians, and mollusks do not have a proboscis.
Pregunta 36 Informe
Which of the following is caused by Treponema palladium?
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Pregunta 37 Informe
Which of the following helps in the clotting of blood?
Detalles de la respuesta
Platelets are the blood cells that help in the clotting of blood. When there is an injury or damage to a blood vessel, platelets rush to the site of injury and form a plug to stop the bleeding. Platelets are tiny cell fragments that are produced in the bone marrow and circulate in the blood. They contain special proteins and enzymes that help them to stick together and form a clot. The clotting process begins when platelets are activated by a signal from damaged tissue or blood vessel. Once activated, the platelets stick together to form a plug that helps to stop bleeding. The clotting process is also aided by a number of clotting factors that are present in the plasma, the liquid part of the blood. Red blood cells carry oxygen to the body's tissues, while white blood cells help to fight infections. However, neither of these cell types are directly involved in the clotting process. In summary, platelets are the blood cells that help in the clotting of blood, by forming a plug at the site of injury or damage to a blood vessel.
Pregunta 38 Informe
Detalles de la respuesta
Pregunta 39 Informe
A tropical disease caused by Trypanosoma is
Detalles de la respuesta
Sleeping sickness, also known as African trypanosomiasis, is a tropical disease caused by the parasite Trypanosoma. It is transmitted to humans through the bite of infected tsetse flies. The disease affects the central nervous system and can lead to confusion, behavioral changes, and eventually, coma and death if left untreated. Sleeping sickness is prevalent in sub-Saharan Africa and is considered a neglected tropical disease by the World Health Organization.
Pregunta 40 Informe
The blood circulatory system of vertebrates consists of
Detalles de la respuesta
The blood circulatory system of vertebrates, including humans, consists of four main components: the heart, arteries, capillaries, and veins. The heart pumps blood, which is rich in oxygen and nutrients, to the rest of the body through a large artery called the aorta. The arteries branch off into smaller vessels and eventually into tiny capillaries. Capillaries are the smallest blood vessels and are responsible for delivering oxygen and nutrients to cells while removing waste products. After passing through the capillaries, the blood then flows into the veins, which gradually increase in size as they merge together to form larger vessels that eventually lead back to the heart. The largest veins in the body are the vena cava, which bring blood back to the heart from the body's lower and upper halves. This continuous loop of blood flow enables the body to receive the necessary oxygen and nutrients it needs to function properly, while also removing waste products like carbon dioxide.
Pregunta 41 Informe
The process of transforming the chemical energy of cellular fuels into the high energy bonds of ATP in plants is
Detalles de la respuesta
The process of transforming the chemical energy of cellular fuels into the high energy bonds of ATP in plants is called respiration. During respiration, organic molecules such as glucose are broken down in the presence of oxygen to release energy. This energy is then used to make ATP, which is the main source of energy for all cellular activities in plants. In contrast, photosynthesis is the process by which plants use light energy to convert carbon dioxide and water into glucose and oxygen. This glucose can then be used in respiration to produce ATP. Photolysis is a process of splitting water molecules into oxygen and hydrogen ions, which occurs during photosynthesis. Autotrophism is a characteristic of organisms that can produce their own food, such as plants, through processes like photosynthesis. Therefore, while photosynthesis and autotrophism are important processes for plants to produce their own food, respiration is the process by which plants use this food to produce ATP and provide energy for all cellular processes.
Pregunta 42 Informe
Which of the following types of feathers is used for flight in birds?
Detalles de la respuesta
The type of feather that is used for flight in birds is called a "quill" feather. Quill feathers are large, strong, and stiff feathers located on the wings and tail of birds. They are responsible for providing lift and control during flight. Quill feathers have a central shaft or "quill" that is surrounded by many small branches or "barbs". These barbs are interlocked with each other, forming a flat surface that helps birds to fly. Additionally, quill feathers are coated with a special oil that makes them water-resistant and helps to keep birds dry while they are in flight.
Pregunta 43 Informe
The long and sharp clawed feet of birds is an adaptation for
Detalles de la respuesta
Birds have long and sharp clawed feet, also known as talons, to help them grasp their prey. These talons are specially adapted for catching and holding onto prey tightly, allowing birds to capture and eat their food effectively. The size and shape of the talons can vary depending on the bird's diet and hunting habits. For example, raptors such as eagles and hawks have large, powerful talons that are designed to grasp and kill prey, while birds that eat smaller prey, such as songbirds, have smaller, more delicate talons. So, the answer is that the long and sharp clawed feet of birds is an adaptation for grasping prey.
Pregunta 44 Informe
Physiological adaptation to very dry conditions in animals demonstrates
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Pregunta 45 Informe
Plants that have special devices for trapping and digesting insects are
Detalles de la respuesta
Plants that have special devices for trapping and digesting insects are called carnivorous plants. These plants have adapted to living in nutrient-poor environments, such as bogs and swamps, by evolving unique ways of obtaining the nutrients they need. By trapping and digesting insects, carnivorous plants can obtain nitrogen and other essential nutrients that are lacking in their soil. Carnivorous plants have various mechanisms for capturing their prey, such as sticky surfaces, pitcher-shaped leaves, or snap traps. Once an insect has been caught, the plant secretes enzymes that break down the insect's tissues and release the nutrients that the plant needs. Some examples of carnivorous plants include the Venus flytrap, the pitcher plant, and the sundew. These plants are fascinating examples of how nature can adapt and evolve to survive in even the harshest of environments.
Pregunta 46 Informe
The structural adaptation of desert plants for water conservation is
Detalles de la respuesta
Desert plants have developed various structural adaptations to conserve water due to the arid environment they live in. One of these adaptations is having spiny leaves. The spines reduce the surface area of the leaves, which helps to reduce water loss through transpiration. Another adaptation is the presence of spongy mesophyll tissue in the leaves. This tissue is able to store water for the plant to use during dry periods. Additionally, the leaves may have prominent stomata, which are openings that allow for gas exchange. These stomata are typically found on the underside of the leaves to help reduce water loss through transpiration. In contrast, broad leaves with numerous stomata would not be an effective adaptation for desert plants, as they would lose too much water through transpiration in the hot, dry environment. Therefore, desert plants have evolved specific adaptations to thrive in their unique ecosystem.
Pregunta 47 Informe
Taenia solium can be found in
Detalles de la respuesta
Taenia solium is a parasite that can be found in pigs. This parasite can cause a disease called cysticercosis, which can be harmful to humans if they accidentally consume undercooked or raw infected pork. Pigs can become infected with the parasite by eating infected human feces, which contains the parasite's eggs. To avoid getting sick, it is important to cook pork thoroughly and to practice good hygiene, especially in areas where Taenia solium is common.
Pregunta 48 Informe
The transfer of pollen grains from the anther to a sigma is
Detalles de la respuesta
The transfer of pollen grains from the male part of a flower, called the anther, to the female part of a flower, called the stigma, is called pollination. Pollination is a very important step in the process of sexual reproduction in flowering plants because it allows the male gamete (sperm) to reach the female gamete (egg) for fertilization, which leads to the formation of seeds. There are two main types of pollination: self-pollination and cross-pollination. Self-pollination occurs when the pollen from the anther of a flower lands on the stigma of the same flower or on another flower on the same plant. Cross-pollination occurs when the pollen from the anther of one flower lands on the stigma of another flower on a different plant of the same species. Once the pollen grains land on the stigma, they begin to grow a tube called a pollen tube that grows down through the style towards the ovary. This tube contains the male gamete (sperm) that will fertilize the female gamete (egg) to form a seed. So, to summarize, the transfer of pollen grains from the anther to the stigma is called pollination, which is an important step in the sexual reproduction of flowering plants that allows for the formation of seeds.
Pregunta 49 Informe
The organelles present in cells that are actively respiring and photosynthesizing are
Detalles de la respuesta
The organelles present in cells that are actively respiring and photosynthesizing are mitochondria and chloroplasts. Mitochondria are responsible for cellular respiration, the process by which cells convert glucose into ATP (a molecule that provides energy for the cell). They contain enzymes that break down glucose and oxygen to produce ATP, which is used by the cell for various processes. Chloroplasts are responsible for photosynthesis, the process by which plants convert light energy into glucose. They contain chlorophyll, a pigment that captures light energy, and enzymes that use that energy to convert carbon dioxide and water into glucose and oxygen. In summary, mitochondria are responsible for cellular respiration, while chloroplasts are responsible for photosynthesis. These organelles play a crucial role in energy production and are present in cells that are actively respiring and photosynthesizing.
Pregunta 50 Informe
Detalles de la respuesta
The enzyme that is present in the saliva is called ptyalin, also known as salivary amylase. Ptyalin is an enzyme that breaks down carbohydrates, such as starch and glycogen, into smaller molecules like maltose and glucose. This process is called hydrolysis, and it helps to start the digestion of carbohydrates in the mouth. When you eat food, your salivary glands produce saliva that contains ptyalin. As you chew and mix the food with saliva, ptyalin begins to break down the carbohydrates into simpler molecules. This process continues as the food moves through your digestive system, with other enzymes and digestive juices breaking down the food further until the nutrients are absorbed by the body. In summary, ptyalin is an important enzyme present in saliva that helps break down carbohydrates during digestion.
