JAMB UTME - Biology - 2023

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The urinary tubule, a part of the nephron in the kidney, is indeed responsible for the production of urine. It does this by reabsorbing useful substances from the filtrate, such as glucose and ions, and secreting waste products into it. The modified filtrate, now called urine, is then passed on to the bladder for storage and eventual excretion.

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Digestive enzymes play a crucial role in our digestive system. They are responsible for breaking down the food we eat into smaller molecules so that our bodies can absorb the nutrients more easily. When we eat, our food enters the stomach and then moves into the small intestine. Here, the digestive enzymes are released and start breaking down the carbohydrates, proteins, and fats present in our food. These enzymes help break down complex molecules into simpler ones. For example, amylase is an enzyme that breaks down carbohydrates into smaller sugar molecules like glucose. Proteases break down proteins into amino acids, while lipases break down fats into fatty acids and glycerol. Once these molecules are broken down, they can be easily absorbed into the bloodstream through the lining of the small intestine. This is where the nutrients are taken up by our body cells and used for energy, growth, and repair. In addition to breaking down food, digestive enzymes also help in regulating the pH of the digestive tract. The stomach, for instance, has a highly acidic environment due to the presence of hydrochloric acid. Digestive enzymes help maintain the optimal pH level needed for their proper functioning. Lastly, digestive enzymes are also involved in transporting food through the digestive system. Peristalsis, which is the movement of food through the digestive tract, is facilitated by these enzymes. In conclusion, digestive enzymes are responsible for breaking down our food into smaller molecules, absorbing the nutrients into the bloodstream, regulating the pH of the digestive tract, and transporting food through the digestive system. They play a vital role in ensuring proper digestion and nutrient absorption in our bodies.

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Sexual reproduction in organisms involves the fusion of gametes from two parents, resulting in offspring with genetic variation. This means that the offspring inherit traits from both parents, leading to a combination of their genetic material. This process starts with the production of specialized cells called gametes by each parent. These gametes, such as sperms and eggs, contain half the number of chromosomes as other cells in the body. When two gametes fuse during sexual reproduction, they form a new cell called a zygote. The zygote then develops into an offspring with a unique combination of genes from both parents. This genetic variation is beneficial to the survival of a species. It allows for adaptation to changing environments. For example, if one parent has a genetic trait that provides resistance to a certain disease, there is a chance that the offspring may inherit that trait and be better equipped to survive if they encounter the same disease. In contrast, asexual reproduction involves the production of offspring through a single parent, resulting in genetically identical offspring. This can occur through processes such as budding, fragmentation, or binary fission. In asexual reproduction, there is no genetic variation, as the offspring are essentially clones of the parent. So, the true statement regarding sexual reproduction in organisms is that it involves the fusion of gametes from two parents, resulting in offspring with genetic variation.

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Fishes have a swim bladder or air bladder which helps them to remain buoyant without sinking in water. They are present in the body cavity.

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Formation of complex caste systems is an example of an adaptation for survival in social insects. Social insects like ants, bees, and termites live in colonies and work together for the benefit of the entire colony.

Caste systems in social insects are the division of labor within the colony, where individuals are assigned specific roles and tasks based on their physical characteristics and abilities. These castes typically include workers, soldiers, and reproductive individuals such as queens and drones.

The formation of complex caste systems is an important adaptation that helps social insects survive and thrive. Each caste has specific functions and responsibilities. For example, workers are responsible for tasks like foraging for food, building and maintaining the nest, and caring for the young. Soldiers, on the other hand, are responsible for defending the colony against threats.

This division of labor allows social insects to efficiently allocate their resources and adapt to various environmental conditions. It increases their chances of survival and success as a colony.

By having specialized castes, social insects can provide different services simultaneously, allowing the colony to be more efficient and resilient.

Overall, the formation of complex caste systems is a remarkable adaptation in social insects that enables them to effectively carry out their survival tasks and thrive in their habitats.

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The skeletal system in humans is composed of bones and joints. Bones and joints are the primary components of the human skeletal system

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The term "cell" was given by Robert Hooke. He was an English scientist who lived in the 17th century. Hooke is famous for his book called "Micrographia," in which he described his observations under a microscope. In one of his observations, Hooke examined a thin slice of cork and noticed small compartments that reminded him of the empty rooms (cells) where monks lived in monasteries. He called these compartments "cells," and that's how the term came into existence. Although Hooke initially used the term to describe the structures he observed in cork, it was later found that cells are the fundamental units of life in all living organisms. Cells are the building blocks of life and are responsible for carrying out various functions necessary for an organism to survive and thrive. So, to summarize, the term "cell" was given by Robert Hooke when he observed small compartments in cork and named them after the rooms in monasteries. These cells are now known to be the basic units of life in all living organisms.

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Trophic levels in a functioning ecosystem refer to the different levels of energy flow within the ecosystem. To understand this concept, let's imagine an ecosystem like a food pyramid. At the very bottom of the pyramid, we have the producers, which are usually plants or algae. These organisms use energy from the sun to create food through photosynthesis. They are able to convert sunlight into stored energy in the form of carbohydrates. Moving up the food pyramid, we have the herbivores or primary consumers. These are animals that eat the producers directly. They obtain energy by consuming plants or algae. Next, we have the carnivores or secondary consumers. These are animals that eat other animals. They obtain energy by consuming the herbivores. Finally, at the top of the food pyramid, we have the apex predators. These are usually large predators that have no natural predators of their own. They are at the highest trophic level because they obtain energy by consuming other carnivores. Each trophic level represents a different level of energy transfer. As energy flows from one level to the next, there is a decrease in the amount of available energy. This is because not all energy is efficiently transferred from one organism to another. Some energy is lost as heat or used for metabolic processes. In summary, trophic levels in a functioning ecosystem describe the different levels of energy flow within the ecosystem, starting with the producers and progressing through the different levels of consumers.

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A natural habitat in ecology refers to an **area where organisms naturally live and interact with their surroundings**. It is a place where various plants, animals, and other organisms coexist and depend on each other for survival. In a natural habitat, organisms have access to the necessary resources, such as food, water, and shelter, that enable them to thrive and reproduce. It is important to note that natural habitats can vary widely, ranging from forests and grasslands to deserts and oceans. They can be found in different parts of the world, each supporting a unique set of species that are adapted to their specific environment. The diversity and complexity of interactions within a natural habitat contribute to the overall resilience and balance of the ecosystem.

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In monohybrid inheritance, if an organism carries two different alleles for a particular gene, it is called **heterozygous**. Let's break it down to understand why this is the correct answer. Genes are the units of heredity that determine traits in living organisms. Each gene exists in different forms called alleles. In monohybrid inheritance, we focus on the inheritance of a single gene from one generation to the next. When an organism has two copies of the same allele for a gene, it is called **homozygous** for that gene. Homozygous individuals can have two copies of the dominant allele (DD) or two copies of the recessive allele (dd). On the other hand, if an organism carries two different alleles for a gene, it is called **heterozygous**. Heterozygous individuals have one copy of the dominant allele and one copy of the recessive allele (Dd). In this case, the dominant allele often determines the visible trait, while the recessive allele is hidden or masked. To summarize, in monohybrid inheritance, if an organism carries two different alleles for a particular gene, it is called **heterozygous**.

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Cell walls and turgor pressure are the mechanisms responsible for providing support in plants. Unlike animals that have muscles and skeletons for support, plants have cell walls and turgor pressure.

Cell walls: Plant cells have strong and rigid cell walls made of cellulose. These cell walls provide structural support to the entire plant. They help plants maintain their shape and prevent them from collapsing under their own weight. The cell walls also protect the delicate cell membrane and organelles inside the cell.

Turgor pressure: Within plant cells, there is a high concentration of water, and this water creates pressure against the cell walls. This pressure is called turgor pressure. Turgor pressure provides rigidity to plant cells, which in turn helps support the entire plant. When plant cells are well hydrated, turgor pressure keeps them turgid and upright, maintaining the shape and structure of the plant.

Together, the cell walls and turgor pressure work hand in hand to provide support to plants. The cell walls provide a strong framework, while turgor pressure maintains the structural integrity of individual cells.

This combination allows plants to stand upright and resist external forces such as wind or gravity.

To recap, while animals rely on muscles and skeletons for support, plants utilize cell walls and turgor pressure to provide their structural support.

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The process in the nutrient cycle that converts atmospheric nitrogen into a form that plants can utilize is called nitrogen fixation.

Nitrogen gas makes up about 78% of the Earth's atmosphere, but plants cannot directly use this form of nitrogen for their growth and development. They need nitrogen in a different chemical form, like ammonia or nitrate, to be able to absorb it from the soil and use it to build important molecules such as proteins and DNA.

Nitrogen fixation is the process by which atmospheric nitrogen gas is converted into these usable forms of nitrogen. This process is mainly carried out by specialized bacteria, known as nitrogen-fixing bacteria, that are found in the soil or in the root nodules of certain plants, like legumes (e.g., peas, beans, and clover).

These nitrogen-fixing bacteria have a unique ability to convert atmospheric nitrogen gas into ammonia through a series of biochemical reactions.

This ammonia can then be further converted into other forms, such as nitrate or ammonium, which can be taken up by plants and used for their growth.

So, nitrogen fixation is a crucial step in the nutrient cycle as it makes atmospheric nitrogen available to plants, which in turn, becomes a source of nitrogen for other organisms in the ecosystem.

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The organs that are part of the alimentary canal in the human digestive system are the **esophagus, stomach, pancreas, and small intestine**. **Esophagus**: It is a muscular tube that connects the mouth to the stomach. Its role is to transport food from the mouth to the stomach through a process called peristalsis, which is the contraction and relaxation of the muscles in the esophagus. **Stomach**: The stomach is a J-shaped organ located below your diaphragm in the upper-left side of your abdomen. It is an important part of the digestive system because it breaks down food into a liquid mixture called chyme. The stomach has strong muscles that churn and mix the food with digestive juices that contain acids and enzymes. **Pancreas**: The pancreas is a long, flat gland located behind the stomach. It has both endocrine and exocrine functions. In terms of digestion, the pancreas releases digestive enzymes into the small intestine to help break down carbohydrates, fats, and proteins. **Small Intestine**: The small intestine is a long, coiled tube that is the major site of digestion and absorption of nutrients. It is divided into three sections: the duodenum, jejunum, and ileum. The lining of the small intestine has tiny finger-like projections called villi, which increase its surface area for efficient absorption of nutrients into the bloodstream. It's important to note that while the salivary glands, tongue, pharynx, large intestine, appendix, and rectum are all important parts of the digestive system, they are not part of the alimentary canal. The salivary glands produce saliva, the tongue helps with chewing and swallowing, and the pharynx is the pathway for food and air. The large intestine, appendix, and rectum are mainly involved in the absorption of water, electrolytes, and the elimination of solid waste. To summarize, the organs that are part of the alimentary canal in the human digestive system are the **esophagus, stomach, pancreas, and small intestine**. These organs work together to break down food, absorb nutrients, and eliminate waste.

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Viviparity refers to the reproductive strategy in which offspring develop and are nourished inside the female's body. This means that instead of laying eggs externally, like in other reproductive strategies, the female's body provides a protected environment for the embryo to develop and receive nutrients.

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The correct statement is: The heart is a muscular organ that contracts to circulate blood throughout the body.

The heart is a vital organ that keeps us alive by pumping blood continuously throughout our body. It is a muscular organ located in the chest, slightly tilted towards the left.

The main function of the heart is to circulate blood throughout the body, delivering oxygen and nutrients to all the organs and tissues. It does this by continuously contracting and relaxing, creating a pumping action.

The heart is made up of four chambers: two atria (singular: atrium) and two ventricles. The atria receive blood from the veins, while the ventricles pump the blood out of the heart. Deoxygenated blood, which has low oxygen levels and high carbon dioxide levels, enters the right atrium from the body through the superior and inferior vena cava.

The right atrium then contracts, pushing the blood into the right ventricle. From there, it is pumped to the lungs to get oxygenated. In the lungs, oxygen is added to the blood while carbon dioxide is removed. Oxygenated blood returns to the heart, specifically to the left atrium, through the pulmonary veins.

The left atrium contracts, pushing the blood into the left ventricle. The left ventricle, being the strongest chamber, pumps the oxygenated blood out of the heart and into the arteries that supply the rest of the body.

So, the heart does not produce red blood cells or receive blood from the kidneys. Its primary job is to pump oxygenated blood to the lungs for oxygenation and then pump the oxygen-rich blood to the rest of the body.

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Carbohydrates are classified as macronutrients. Macronutrients are the nutrients that our bodies need in large amounts to provide energy and support various functions.

This classification is correct for carbohydrates because they are a primary source of energy for our bodies. Carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen atoms. They are found in a variety of foods such as grains, fruits, vegetables, and dairy products.

Carbohydrates can be further categorized into three types: sugars, starches, and fibers. Sugars are simple carbohydrates that are quickly broken down by the body into glucose, which is used for immediate energy.

Examples of foods high in sugar include table sugar, honey, and fruits. Starches are complex carbohydrates made up of many sugar molecules linked together. They are found in foods like grains, potatoes, and legumes.

Starches take longer to digest and provide a more sustained release of energy compared to sugars. Fiber is also a complex carbohydrate that cannot be fully digested by the body. It passes through the digestive system largely intact and provides important health benefits such as promoting regular bowel movements and supporting gut health.

Fiber is found in foods like whole grains, fruits, vegetables, and legumes. In summary, carbohydrates are classified as macronutrients because they provide our bodies with energy.

They can be classified into sugars, starches, and fibers, each with its own role in our diet.

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Migration is an example of a behavioral adaptation for survival in animals.

Migration is the regular movement of animals from one place to another, usually in search of better resources or favorable conditions. It is a behavior that helps animals survive by allowing them to find food, escape harsh weather conditions, or reproduce successfully.

During migration, animals travel long distances, sometimes across continents or even oceans, to reach their desired destination. They may travel in groups or flocks, following established routes or using environmental cues such as the position of the sun or Earth's magnetic field.

Some well-known examples of migrating animals include birds, butterflies, whales, and wildebeests. Migration is an effective strategy for survival because it helps animals ensure their survival by accessing resources that may be unavailable in their current location.

By moving to areas with more favorable conditions, such as areas with abundant food or suitable breeding grounds, animals increase their chances of survival and reproduction.

In summary, migration is a behavioral adaptation for survival in animals because it allows them to find better resources and escape unfavorable conditions, ultimately increasing their chances of survival and successful reproduction.

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The statement that best describes the role of competition in the process of adaptation is: Competition leads to the selection of individuals with favorable traits for survival and reproduction.

Competition refers to the struggle among individuals for limited resources, such as food, territory, mates, or other necessities for survival. In a population with limited resources, not all individuals can have access to them.

This competition creates a selective pressure which drives the process of adaptation. Adaptation is the process by which individuals become better suited to their environment over time.

Through competition, individuals with advantageous traits, which may include physical characteristics or behaviors, have a higher chance of surviving and reproducing successfully. This is because these individuals are better able to acquire the limited resources compared to those who do not possess these traits.

For example, in a population of birds, competition for food may be fierce. Birds with longer beaks may have an advantage in reaching and eating certain types of food that are otherwise inaccessible to birds with shorter beaks.

Over time, the birds with longer beaks are more likely to survive and pass on their longer beak trait to future generations. Therefore, competition plays a crucial role in the process of adaptation by selecting individuals with favorable traits, enabling them to survive, reproduce, and pass on those traits to future generations.

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Pollination is the process of transferring pollen from the anther to the stigma of a flower.
In simple terms, pollination is like the plant's way of reproduction. It involves the transfer of pollen, which contains the plant's male reproductive cells, from the anther (part of the flower where pollen is produced) to the stigma (part of the flower where pollen needs to land for fertilization).
This transfer can happen in different ways, depending on the plant species. It can be done by wind, insects, birds, or other animals. When pollen reaches the stigma, it can fertilize the female reproductive cells and lead to the formation of seeds and fruits.
To summarize, pollination is the essential step in plant reproduction where pollen is moved from the male part of the flower to the female part, allowing for the production of seeds.

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The primary products of photosynthesis are **glucose and oxygen**. During photosynthesis, plants use sunlight, carbon dioxide, and water to produce glucose, which is a type of sugar. This process occurs in special structures called chloroplasts, which are found in the cells of plants. Here's how it works: 1. **Sunlight**: Plants capture sunlight using a pigment called chlorophyll, which is located in the chloroplasts. This chlorophyll absorbs the energy from sunlight. 2. **Carbon Dioxide**: Plants take in carbon dioxide from the atmosphere through tiny pores called stomata, which are present on their leaves. Carbon dioxide is a gas that is released by animals and is also present in the air we breathe out. 3. **Water**: Plants absorb water from the soil through their roots. This water is then transported up through the stems to the leaves. 4. **Photosynthesis**: Inside the chloroplasts, the energy from sunlight is used to convert carbon dioxide and water into glucose and oxygen. This process involves a series of chemical reactions that occur in multiple steps. The glucose produced during photosynthesis serves as a source of energy for the plant. It can be used immediately, stored as starch for later use, or used to make other compounds needed by the plant. The oxygen produced as a byproduct of photosynthesis is released into the atmosphere through the stomata. It is a vital component for most living organisms, including animals, as we need oxygen to survive and carry out cellular respiration.

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Tropical rains can cause intense leaching, which is the process of nutrients being washed away from the soil. This leaching can have a significant impact on soil fertility. Out of the given options, the soil type that becomes less fertile due to intense leaching caused by tropical rains is laterite soil.

Laterite soil is formed in areas with high temperatures and heavy rainfall, such as tropical regions. It is usually found in regions with a tropical monsoon climate, such as parts of India, Southeast Asia, and parts of Africa.

Because of the intense rainfall in these regions, laterite soil experiences a high degree of leaching. The heavy rainwater carries away the essential nutrients from the soil, making it less fertile over time. These nutrients include vital elements like nitrogen, phosphorus, and potassium, which are crucial for plant growth. As a result of intense leaching, laterite soils can become impoverished and low in nutrients.

This can pose challenges for agriculture as plants need these nutrients to thrive. Therefore, it is important for farmers in such regions to practice appropriate soil management techniques, such as using organic fertilizers or crop rotation, to replenish and maintain the fertility of laterite soil.

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One of the main differences between plant and animal cells is that plant cells contain chloroplasts for photosynthesis, while animal cells do not. However, plant cells contain chloroplasts, which are organelles responsible for photosynthesis, enabling plants to convert sunlight into energy-rich molecules. Animal cells lack chloroplasts and obtain energy through other means, such as consuming organic matter.

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Viruses require a host cell to replicate. Viruses are not living organisms on their own. They are tiny infectious agents that can only replicate and multiply inside the cells of other living organisms. In order to reproduce, viruses depend on a host cell. They infect the host cell and take control of its machinery, directing it to produce more viruses. This process of using the host cell's machinery for replication is known as the viral life cycle. Once the new viruses are produced, they can go on to infect other cells and continue the cycle of reproduction. Therefore, it is true that viruses need a host cell to replicate.

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The most inclusive level of classification in the Linnaean system is the kingdom.

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Behavioral adaptation refers to the actions and behaviors that animals take to survive in their environment. When it comes to dealing with a hot climate, animals have developed various behavioral adaptations to help them cope with the high temperatures.

One example of a behavioral adaptation for dealing with a hot climate is hibernating during the hottest part of the day. Hibernation is a state of deep sleep or dormancy that animals enter to conserve energy and protect themselves from extreme temperatures. By hibernating during the hottest part of the day, animals can avoid exposure to the intense heat and reduce their risk of overheating.

Another behavioral adaptation is having large scales on the back of a lizard. These scales act as a protective layer, shielding the lizard from direct sunlight and reducing heat absorption. The large scales help to reflect sunlight away from the lizard's body, keeping it cooler in hot climates.

Contrary to what one might expect, feeding during the hottest part of the day can also be a behavioral adaptation to deal with a hot climate. While it may seem counterintuitive, by feeding during this time, animals can take advantage of the increased availability of food. Many insects and small animals are more active during the daytime to avoid predators that are less active in the heat. By feeding during the hottest part of the day, animals can also conserve energy and avoid the need to search for food in hotter conditions later on.

Lastly, having a small kidney to conserve water is another behavioral adaptation for dealing with a hot climate. In a hot environment, water becomes a scarce resource, so animals need to be efficient in conserving and utilizing it. Having a small kidney allows the animal to produce less urine and retain more water in its body, preventing dehydration.

In summary, behavioral adaptations for dealing with a hot climate include hibernating during the hottest part of the day, having large scales on the back of a lizard, feeding during the hottest part of the day, and having a small kidney to conserve water. These adaptations help animals minimize heat exposure, reduce water loss, and maximize energy efficiency in hot environments.

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The factor that primarily affects the distribution of organisms in an ecosystem is **temperature**. Temperature plays a crucial role in determining where different organisms can survive and thrive. Organisms have specific temperature ranges called their "optimal temperature range", within which they can function and grow most effectively. This range varies for different species. Some organisms, such as tropical plants and animals, thrive in hotter temperatures, while others, like polar bears and Arctic plants, are adapted to colder temperatures. Temperature affects the distribution of organisms in several ways. First, it determines the availability of water. Warmer temperatures lead to evaporation and increased water vapor in the air, which can result in areas with high humidity. This higher humidity may support different types of organisms compared to areas with lower humidity. Second, temperature affects the metabolism and physiological processes of organisms. Higher temperatures generally speed up biological processes, while lower temperatures slow them down. As a result, organisms have specific temperature thresholds beyond which they struggle to survive. For example, if the temperature becomes too hot, certain plants may wilt or die, while cold-blooded animals like reptiles may become sluggish or unable to move. Third, temperature influences the growth and reproduction of organisms. Some plants require specific temperature conditions to flower and produce fruit, while animals may have specific temperature requirements for breeding and reproduction. Lastly, temperature also affects the availability of resources for organisms. Different temperatures may lead to variations in the abundance and distribution of food sources, as well as availability of shelter and other resources necessary for survival. In summary, temperature is the primary factor that affects the distribution of organisms in an ecosystem. It determines the availability of water, influences biological processes and metabolism, affects growth and reproduction, and impacts resource availability.

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An example of a microorganism in action as a disease vector is the mosquito transmitting malaria. Mosquitoes are tiny insects that can carry the malaria parasite from an infected person to a healthy person through their bites. Malaria is a disease caused by a microscopic parasite called Plasmodium. When a mosquito bites a person infected with malaria, it sucks up the Plasmodium parasites along with the person's blood. Inside the mosquito, the parasites go through a complex life cycle and multiply. When the mosquito bites another person, it injects saliva containing the malaria parasites into the healthy person's bloodstream. The parasites then travel to the person's liver and red blood cells, where they continue to multiply, causing the symptoms of malaria. This means that the mosquito acts as a vector, carrying and transmitting the disease-causing microorganism (Plasmodium) from one person to another. Mosquitoes are responsible for spreading malaria, which is a major health concern in many parts of the world, especially in tropical and subtropical regions. It's important to note that while fungi decomposing dead plant material, bacteria causing food poisoning, and algae producing oxygen through photosynthesis are all examples of microorganisms, they do not typically act as disease vectors like the mosquito in the case of malaria transmission.

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A characteristic of cells related to irritability is the ability to respond to stimuli.

This means that cells can detect changes in their environment and react accordingly. Cells have specialized structures called receptors that can detect different types of stimuli such as light, temperature, chemicals, or pressure.

When a stimulus is detected, the cell can initiate a series of events to respond to it. This response can involve various cellular processes such as changing the cell's shape, releasing chemicals, or activating specific genes to produce proteins. For example, when your skin cells are exposed to heat, the receptors in those cells detect the change in temperature.

In response, the cells generate signals that travel to the brain, allowing you to feel the heat and take appropriate action like moving your hand away from the source of heat.

In summary, the ability to respond to stimuli is an important characteristic of cells related to irritability because it allows them to interact with their surroundings and adapt to changes in their environment.

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The correct option that identifies excretory organs in animals is Lungs, kidneys, and skin.

Excretion is the process by which waste products are removed from an organism's body. Organisms produce waste as a result of their metabolic processes, and these waste products need to be eliminated from the body to maintain a healthy internal environment. Let's now examine each organ mentioned in the correct option:

1. Lungs: Lungs are the main respiratory organs in most animals. They play a crucial role in the process of respiration, which involves the exchange of gases between the body and the environment. During respiration, carbon dioxide, which is a waste product of cellular respiration, is eliminated through exhalation.

2. Kidneys: Kidneys are the primary excretory organs in animals. They filter the blood and regulate the composition of body fluids by removing waste products such as urea, excess water, and ions. The waste products filtered by the kidneys are then excreted as urine.

3. Skin: The skin, which is the largest organ in the body, also plays a role in excretion. It contains sweat glands that excrete sweat, a watery fluid that helps cool the body and removes certain waste products such as urea and salts.

In summary, the lungs eliminate carbon dioxide, the kidneys eliminate waste products through urine, and the skin excretes sweat. These three organs, lungs, kidneys, and skin, collectively facilitate the process of excretion in animals.

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One characteristic feature of Kingdom Plantae is the ability to perform photosynthesis. Photosynthesis is the process by which plants use sunlight, carbon dioxide, and water to produce glucose (a sugar) and release oxygen as a byproduct. This process occurs within specialized organelles called chloroplasts, which are found in plant cells. Chloroplasts contain a pigment called chlorophyll that absorbs light energy from the sun and facilitates the conversion of carbon dioxide and water into glucose and oxygen. Through photosynthesis, plants are able to produce their own food and energy, making them autotrophs. Autotrophs are organisms that can synthesize organic compounds from inorganic substances. This ability allows plants to sustain themselves and support the growth and development of their tissues and structures. The presence of chloroplasts and the ability to perform photosynthesis are crucial characteristics that differentiate Kingdom Plantae from other kingdoms, such as Kingdom Animalia. Animals lack chloroplasts and are unable to produce their own food through photosynthesis. Instead, animals usually obtain their energy by consuming other organisms, making them heterotrophs. Therefore, the correct characteristic feature of Kingdom Plantae is the ability to perform photosynthesis.

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Cell growth refers to the increase in size and mass of a cell. It is an essential process for living organisms as it allows them to develop and maintain healthy bodily functions. Now, let's address each statement and determine which one is true. 1. **Cell growth is solely influenced by external factors:** This statement is not true. While external factors such as nutrients, temperature, and pH can influence cell growth, it is not solely dependent on them. Internal factors, such as the genetic makeup of the cell and its ability to respond to signals, also play a crucial role in cell growth. 2. **Cell growth is a continuous process throughout the life of a cell:** This statement is also not true. Cell growth is generally a controlled process and takes place at specific times during the cell's life cycle. In some cases, cells can even stop growing and enter a state of dormancy or apoptosis (programmed cell death). So, cell growth is not continuous throughout the life of a cell. 3. **Cell growth involves an increase in the number of organelles within a cell:** This statement is partially true. While cell growth can involve an increase in the number of organelles within a cell, it is not the only factor. Cell growth also includes an increase in the size and volume of organelles, as well as the synthesis of new proteins and genetic material. 4. **Cell growth occurs by cell division:** This statement is true. Cell growth most commonly occurs through cell division, where a single cell divides into two daughter cells. This process, known as mitosis, allows for cell multiplication and subsequent growth of tissues and organs in multicellular organisms. In conclusion, the true statement regarding cell growth is that it occurs by cell division. However, it is important to note that cell growth is not solely influenced by external factors and is not a continuous process throughout the life of a cell. It involves not only an increase in the number of organelles but also an increase in their size and volume.

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Population ecology is the scientific study of how populations of living organisms interact with each other and their environment. It focuses on understanding the distribution, abundance, and dynamics of populations within a species. This field of study aims to answer questions such as why certain species are more abundant in certain areas, how populations change over time, and how they interact with other populations in their ecosystem. Population ecology also examines the factors that influence the growth and decline of populations, including birth rates, death rates, immigration, and emigration. By studying these factors, scientists can gain insights into the mechanisms that regulate population sizes. In summary, population ecology is concerned with understanding the relationships between individuals of the same species and how they are influenced by their environment. It helps us understand how populations change, adapt, and interact within ecosystems.

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An abiotic ecological factor refers to a non-living component of the environment that can affect living organisms. Out of the options provided, **temperature** is an example of an abiotic ecological factor. Temperature plays a crucial role in shaping the environment and influencing the distribution and survival of living organisms. It is a measure of how hot or cold a place or object is. For organisms, temperature affects their physiology, behavior, and overall survival. Different species have specific temperature ranges within which they can function optimally. Too high or too low temperatures can have adverse effects on their growth, reproduction, and overall health. Temperature influences the rate of biological processes in organisms. For example, enzymes, which are essential for various biochemical reactions in living things, have an optimum temperature at which they work most efficiently. Deviation from this temperature can cause enzymes to denature or become less effective, affecting an organism's ability to carry out essential metabolic functions. Moreover, temperature influences the availability and movement of water, which is a vital resource for living organisms. In colder environments, water may freeze, limiting its availability, while in hotter environments, water may evaporate quickly, making it harder for organisms to obtain and conserve water. In conclusion, **temperature** is an abiotic ecological factor because it is a non-living component that significantly affects the distribution, physiology, and overall survival of living organisms.

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The type of reproduction that involves the fusion of gametes from two parents is sexual reproduction.

In this process, two parents contribute their genetic material to produce offspring that inherits traits from both parents. Sexual reproduction involves the fusion of two specialized cells called gametes.

Gametes are produced by the parents and they contain half of the genetic information of each parent. In most animals, the male parent produces small motile gametes called sperm, while the female parent produces larger non-motile gametes called eggs. During sexual reproduction, the sperm and egg unite in a process called fertilization. This fusion forms a new cell called a zygote.

The zygote then develops into an offspring with a unique combination of genetic traits inherited from both parents. The process of sexual reproduction introduces genetic diversity among offspring.

This genetic diversity is important for the survival and adaptation of species to changing environments. It allows for the combination and recombination of genetic traits, enhancing the chances of producing offspring with advantageous characteristics.

Overall, sexual reproduction is a complex and fascinating process that involves the fusion of gametes from two parents, leading to the creation of genetically diverse offspring.

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The primary function of the liver in the human body is **detoxification and metabolism** of various substances. The liver acts as a filter, breaking down and removing toxins such as alcohol, drugs, and other waste products from the bloodstream. It also plays a crucial role in the metabolism of nutrients, including carbohydrates, proteins, and fats. Furthermore, the liver produces bile, a substance that helps in the digestion and absorption of fats. It also stores essential vitamins and minerals, such as vitamin A, D, and B12, as well as iron and copper. In addition to its detoxification and metabolic functions, the liver is involved in the production of blood-clotting proteins and the breakdown of old red blood cells. Overall, the liver is an incredible organ that carries out numerous vital functions to keep our body running smoothly and in a healthy state.

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Ecological management and conservation through a biological association refers to a practice where a specific ecological system is protected and managed by using the interactions and relationships between different organisms within that system. Out of the given options, the **establishment of marine protected areas** represents an example of ecological management and conservation through a biological association. Marine protected areas are specific zones in the ocean where human activities, such as fishing or oil drilling, are restricted or prohibited. They are designed to conserve and protect marine biodiversity, ecosystems, and natural resources. Marine protected areas work by allowing ecosystems to function naturally, and they rely on the interactions between the different organisms within the marine environment. By restricting human activities, these areas provide essential habitats for marine species to reproduce, feed, and seek shelter. The establishment of marine protected areas promotes ecological balance and helps protect vulnerable and endangered species. It also allows for the recovery and regeneration of damaged marine ecosystems. In summary, the establishment of marine protected areas represents an example of ecological management and conservation through a biological association because it utilizes the natural interactions and relationships between organisms in the marine environment to preserve and protect the ecosystem for future generations.

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The liver is NOT a part of the alimentary canal. The alimentary canal, also known as the digestive tract, is a long tube that starts from the mouth and ends at the anus. It is responsible for the process of digestion and absorption of nutrients from the food we eat.

The oesophagus is a muscular tube that connects the mouth to the stomach. It allows food to pass from the mouth to the stomach by a process called swallowing.

The small intestine is the longest part of the digestive tract, where most of the digestion and absorption of nutrients take place. It receives the partially digested food from the stomach and breaks it down further with the help of enzymes, before absorbing the nutrients into the bloodstream.

The large intestine is the final part of the digestive system. It is responsible for absorbing water and electrolytes from the remaining indigestible food matter, and forming solid waste (feces) that is expelled from the body. However, the liver is not a part of the alimentary canal. It is an important organ located in the upper right side of the abdomen.

The liver has numerous functions in the body, including production of bile, which helps in the digestion and absorption of fats. While the liver plays a crucial role in digestion, it is not a structural part of the alimentary canal itself.

In summary, the liver is NOT a part of the alimentary canal. The oesophagus, small intestine, and large intestine are all parts of the alimentary canal responsible for the digestion and absorption of nutrients.

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The plant hormone responsible for promoting cell elongation and growth is **Gibberellins**. Gibberellins play a vital role in regulating plant growth and development. They are primarily responsible for promoting cell elongation, which leads to the growth of stems and leaves. When plants receive signals such as sunlight or changes in their environment, they produce gibberellins. These hormones then move throughout the plant, stimulating the cells to elongate. This elongation allows the stems and leaves to grow taller or expand in size, enabling the plant to reach for sunlight, absorb nutrients, and carry out other essential functions. In addition to promoting cell elongation, gibberellins also influence other aspects of plant growth, such as seed germination, flowering, and fruit development. They can break seed dormancy, ensuring that the seed sprouts and grows into a seedling. They also regulate the flowering process, helping plants transition from vegetative to reproductive stages. Lastly, gibberellins control fruit development by influencing cell division, expansion, and ripening. In summary, gibberellins are plant hormones responsible for promoting cell elongation and growth. They play a crucial role in regulating various aspects of plant development, from stem and leaf growth to seed germination, flowering, and fruit development.

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Vegetative propagation is a method of asexual reproduction in plants. It involves the production of new plants from vegetative parts of an existing plant, such as leaves, stems, or roots. In this process, specialized cells present in these vegetative parts undergo cell division and differentiation to form new plant structures.

These structures can develop into independent, full-grown plants that are genetically identical to the parent plant. Vegetative propagation occurs in various ways:

1. Stem cuttings: A portion of a stem (with leaf nodes) is cut from a parent plant and placed in a suitable medium, where it develops roots and grows into a new plant.

2. Root cuttings: Portions of a root are cut and planted, and they produce new shoots and roots, forming a new plant.

3. Leaf cuttings: Leaves are detached from a parent plant, and specific parts of the leaf develop into roots, stems, and eventually, new plants.

4. Suckers and runners: Some plants produce horizontal stems called runners or suckers that grow from the base of the parent plant. These stems develop roots and give rise to new plants.

This method of asexual reproduction is advantageous because it allows plants to produce offspring quickly without relying on pollination or fertilization. It also ensures that the offspring are genetically identical to the parent, maintaining desirable traits and characteristics.

In summary, vegetative propagation is a form of asexual reproduction in plants where new plants are produced from vegetative parts of an existing plant, such as stems, roots, or leaves. It helps plants multiply quickly and maintain genetic uniformity.

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The alternate form of a gene is called an allele. An allele is a specific version or variant of a gene that codes for a particular trait or characteristic. Genes are sections of DNA that contain instructions for building and function of our bodies. They determine things like our eye color, hair texture, and the ability to taste certain flavors. Each gene can have different forms or variations, known as alleles. These alleles can be slightly different in their DNA sequence, resulting in different traits or characteristics being expressed. For example, the gene for eye color can have alleles for blue, brown, or green eyes. When a person inherits two different alleles of a gene, one from each parent, they are said to be heterozygous for that gene. In this case, one allele may be dominant, which means its trait will be expressed, while the other allele may be recessive, which means its trait will only be expressed if the dominant allele is not present. The way in which alleles interact with each other determines the inheritance patterns and the traits we observe. It is important to note that alleles can be dominant or recessive depending on the trait being considered. So, it is not accurate to say that alleles themselves are dominant or recessive, but rather how they interact with each other in the context of a specific gene.