JAMB UTME - Biology - 2024

The pigment carrying oxygen in the blood is

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The pigment responsible for carrying oxygen in the blood is haemoglobin. Haemoglobin is a complex protein found in red blood cells. Its primary function is to transport oxygen from the lungs to the rest of the body and return carbon dioxide from the body to the lungs for exhalation. Each haemoglobin molecule can bind to four oxygen molecules, allowing it to carry and efficiently distribute a large amount of oxygen throughout the body.

Here's a simple explanation of how it works:

• Haemoglobin binds with oxygen in the lungs, forming oxyhaemoglobin, which gives blood its bright red color.
• This oxyhaemoglobin travels through the bloodstream to tissues and organs, where it releases the oxygen for cell respiration.
• As it releases oxygen, it picks up carbon dioxide, a waste product from cells, and becomes deoxygenated, giving it a darker color.
• The deoxygenated blood returns to the lungs, where carbon dioxide is released, and the cycle repeats.

It is essential to note that while oxyhaemoglobin is simply haemoglobin that has combined with oxygen, the fundamental oxygen-carrying pigment itself is still haemoglobin.

Gaseous exchange takes place through the plasma membrane in

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Gaseous exchange is a biological process through which different gases are transferred in opposite directions across a specialized respiratory surface. When it comes to simple organisms, this exchange can occur directly through the plasma membrane. The organism where gaseous exchange takes place through the plasma membrane is the paramecium.

Here is a simple explanation:

• Hydra: This is a simple aquatic organism; gaseous exchange can occur through its entire body surface because of its simple body structure.
• Paramecium: As a single-celled organism, paramecium relies on its plasma membrane for gaseous exchange. Oxygen from the surrounding water diffuses across the membrane into the cell, and carbon dioxide diffuses out. The plasma membrane is thin and semi-permeable, allowing this process to happen effectively.
• Flatworm: Flatworms have a larger surface area compared to their volume, and they also rely on diffusion through their body surface for gaseous exchange.
• Earthworm: This is a more complex organism. Earthworms have a moist skin through which gaseous exchange takes place. They possess a dense network of capillaries under the skin that facilitates this exchange.

In conclusion, paramecium utilizes its plasma membrane for gaseous exchange due to its single-celled structure, allowing direct diffusion of gases.

The type of variation where there are no remarkable differences between the two extreme individuals is called

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The type of variation where there are no remarkable differences between the two extreme individuals is called continuous variation.

In biology, variation refers to the differences among individuals within a population. When we refer to continuous variation, we're talking about traits that are measured on a scale and show a range of small differences between individuals. An example is human height or weight. In these cases, individuals do not fall into a finite or distinct number of categories, but rather display a smooth and gradual transition across a range.

This type of variation typically results from the combined effects of many genes (polygenic inheritance) and the influence of environmental factors. It presents as a continuous range of expression, forming a bell-shaped curve when graphed, rather than discrete categories. Because of this smooth transition without sharp differences, it's termed as continuous variation.

Similar structures that are modified to work in different ways in different organisms are referred to as

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Structures that are similar in form and origin but have been **modified** over time to function differently in various organisms are known as **homologous structures**. These structures indicate a common evolutionary ancestor. For example, the forelimbs of humans, bats, whales, and cats have the same basic bone structure but have adapted differently for tasks such as grabbing, flying, swimming, and walking. Each of these organisms developed modifications in their limb structure to suit their environment and lifestyle, which showcases the concept of homologous structures. Unlike **analogous structures** that have similar functions in different organisms but different evolutionary origins, homologous structures emphasize a common ancestry with different functional outcomes.

A medium texture soil with high organic matter is

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A medium texture soil with high organic matter is best described as loamy soil. Here is why:

Loamy soil is a mix of three main soil types: sand, silt, and clay. This combination creates a soil that is rich in organic matter and nutrients, providing an excellent environment for plant growth.

Key Characteristics of Loamy Soil:

• It has a balanced texture, giving it good drainage and water retention capabilities, which are important for plant roots to access both air and water effectively.
• This soil type contains enough organic matter to support healthy plant life, as it facilitates nutrient absorption and microbial activity.
• Loamy soil is often referred to as the ideal gardening soil due to its ability to maintain structure and support plant health.

Understanding the benefits and characteristics of loamy soil can help in recognizing its importance in agriculture and gardening. Unlike clay or sandy soils, which might have issues with drainage or nutrient retention respectively, loamy soil offers a balance that is conducive for a wide variety of plants.

The changes of living organisms over generation is referred to as

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The process by which living organisms change over generations is referred to as organic evolution. This concept explains how species undergo gradual change over long periods of time, which can ultimately result in the emergence of new species. These changes are brought about by mechanisms such as mutation, natural selection, gene flow, and genetic drift. As a result, populations of organisms adapt to their environments and can become better suited to survive and reproduce. The concept of organic evolution is a fundamental principle in biology, as it helps us understand the history of life on Earth and the shared ancestry of all living organisms.

The cell organelle responsible for the synthesis of protein is the 

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The cell organelle responsible for the synthesis of protein is the ribosome.

To put it simply, ribosomes are like tiny factories within the cell. They read the genetic instructions carried by messenger RNA (mRNA) and use these instructions to assemble amino acids into proteins, which are essential molecules for various cell functions.

Here's how it works in a straightforward manner:

• The cell's DNA contains the "blueprint" for proteins. This information is copied into mRNA in a process called transcription.
• The mRNA travels to the ribosome. The ribosome reads the sequence of the mRNA. This process is called translation.
• As it reads the mRNA sequence, the ribosome assembles amino acids in a specific order, creating a protein chain, which eventually folds into a functional protein.

In summary, the ribosome is an essential organelle for protein synthesis, which is crucial for the cell's structure, function, and regulation of the body's tissues and organs.

The causative agent of tuberculosis is

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Tuberculosis, often abbreviated as TB, is a disease that primarily affects the lungs, although it can spread to other parts of the body. The **causative agent** of tuberculosis is a specific type of **bacteria** known as Mycobacterium tuberculosis.

To understand this better, let's break it down:

• Definition of Bacteria: Bacteria are microscopic, single-celled organisms. They can be found everywhere and can be helpful or harmful to humans. In the case of tuberculosis, the bacteria are harmful.
• Mycobacterium tuberculosis: This bacterium is rod-shaped and has a thick, waxy coat, which makes it different from many other types of bacteria. This unique structure allows it to survive in harsh environments, including the human body.

When someone with active tuberculosis coughs, sneezes, or even speaks, the bacteria can be spread through the air and inhaled by others, leading to new infections. This is why tuberculosis is described as a **contagious** disease.

Understanding that tuberculosis is caused by **bacteria** is crucial for its treatment and prevention. Antibiotics, which are medicines that specifically target bacterial infections, are used to treat and control the spread of tuberculosis.

In summary, it's important to recognize that tuberculosis is caused by a specific type of bacteria called Mycobacterium tuberculosis, which explains why antibiotics can be effective in its treatment.

Xerophytes are mostly found in the

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Xerophytes are mostly found in arid land. Arid lands are environments that receive very low rainfall, typically classified as deserts or semi-deserts. These areas are characterized by extreme dryness and have conditions that make it difficult for most plants to survive.

Xerophytes are a type of plant specifically adapted to survive in these dry environments. They have special features that help them conserve water. These adaptations include thick, waxy leaves, reduced leaf sizes, deep root systems, and the ability to store water in their tissues. By being able to withstand long periods of drought, xerophytes thrive where other plants cannot.

In contrast, areas like the tropical rainforest and montane forest are characterized by high levels of rainfall and humidity, which support a diverse range of plant and animal life. Similarly, the Sudan savanna has more rainfall than arid lands and supports grasslands and woody plants. Therefore, the environment of arid land is significant to the existence of xerophytes.

Which of the following characteristics is possessed by both living and non-living things?

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In considering the given options, the characteristic that is possessed by both living and non-living things is that they both have weight.

Here is the simple explanation:

• Both age and die: This characteristic applies exclusively to living things. Living organisms grow, age, and eventually die as part of their life cycle. Non-living things do not age or die.
• Both have life: By definition, only living things possess life. Non-living entities do not have life.
• Both have weight: This is the characteristic that applies to both living and non-living things. Every object that has mass is influenced by gravity, which gives it weight. Hence, both living organisms and non-living objects have weight.
• Both have no shape: This is incorrect. While gases may have no definite shape, many non-living things like rocks, tables, or buildings have specific shapes. Conversely, many living organisms, like animals and plants, also have definite shapes.

Therefore, the characteristic of having weight is shared by both living and non-living things.

Comparative anatomy to study evidence for evolution depends on

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**Comparative anatomy** involves studying the similarities and differences in the anatomy of different species. One of its main purposes in understanding **evolution** is to trace how organisms are related through common ancestry. When we look at the limbs of different animals, some specific features provide essential evidence for evolution.

A key feature often examined is the structure of the limbs of vertebrates, which have evolved to adapt to different environments and modes of living, but share a basic underlying structure. This shared structure is often referred to as the **pentadactyl limb** pattern. The term "pentadactyl" means **five-fingered** or having five digits.

In many vertebrates like humans, whales, bats, and so forth, this **five-fingered** limb structure can be observed, although it has evolved to perform different functions in each species. For example, a human hand, a bat's wing, and a whale's flipper all have the same basic arrangement of bones. This points to the fact that these species share a **common ancestor** and have evolved differently as they adapted to their environments.

Thus, comparative anatomy's focus on the **five-fingered** pattern in limbs is crucial as it provides **evidence** of evolutionary relationships among diverse species, illustrating how they have evolved from a shared ancestry.

Ecological succession can result from 

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Ecological succession is a natural process by which ecosystems change and develop over time. This process can be initiated by several factors, resulting in the gradual replacement of one community by another until a stable ecosystem, known as a climax community, is achieved.

One such factor that can lead to ecological succession is a newly formed habitat. When an area is newly formed, such as from a volcanic eruption creating new land, or when a glacier retreats exposing bare rock, there is no pre-existing community. Over time, pioneer species such as lichens and mosses begin to colonize the area. As they die and decompose, they contribute organic matter to the soil, making it more hospitable for future plant species. This leads to the gradual development of a more complex community.

A habitat with abundant food might not directly cause ecological succession, but it can support the growth and reproduction of organisms, contributing to the stability and complexity of existing ecosystems. However, changes in food availability can lead to shifts in populations and species interactions, indirectly influencing successional changes.

Another important factor is a habitat with space and light. When a disturbance such as a fire clears an area, removing trees and other vegetation, it creates open space and increases light availability. This situation allows new species to colonize the area, starting a process known as secondary succession. Initially, fast-growing species that require a lot of light dominate the area, but eventually, as the ecosystem matures, it becomes more diverse and balanced.

Lastly, a population of plants on fertile land provides a suitable environment for ecological succession. Fertile soils support a wide variety of plant species, which contribute to the formation of a complex and stable ecosystem over time. As plants grow and die, they enrich the soil, promoting the growth of secondary species until a mature community is established.

In summary, ecological succession can result from newly formed habitats, disturbances that create space and light, and fertile lands. These changes create conditions that allow different species to colonize and thrive, leading to the evolution of ecosystems over time.

In which zone of the marine habitat does the organisms require adaptation for attachment?

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The marine habitat is divided into various zones, each with its own environmental conditions and challenges for the organisms living there. Among these zones, the intertidal zone is the one where organisms require significant adaptation for attachment. The intertidal zone is the area that is exposed to the air at low tide and submerged under water at high tide.

The main reasons organisms need adaptations for attachment in this zone are:

• Wave Action: The intertidal zone experiences strong waves and tidal currents that can easily dislodge organisms from the substrate. To survive, organisms like barnacles and mussels have developed strong attachments, like suction cups or byssal threads, that help them cling to rocks and other surfaces.
• Changing Environmental Conditions: As the tide rises and falls, organisms in the intertidal zone must endure both aquatic and terrestrial conditions. They need to remain attached to a stable surface to avoid being swept away by the tides.
• Preventing Desiccation: During low tide, when they are exposed to air, organisms must prevent drying out. Remaining attached to a secure surface allows them to find crevices or use their protective shells effectively.

Therefore, the intertidal zone specifically requires organisms to have adaptations that ensure they remain securely attached despite the dynamic and challenging conditions encountered daily.

A fruit formed from one flower with many carpels is referred to as

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A fruit formed from one flower with many carpels is referred to as an aggregate fruit.

Let me break that down further for clarity: When a single flower contains multiple ovaries (carpels), each of these ovaries can develop into a small fruit. These small fruits collectively form what is known as an aggregate fruit. This means that although the fruit appears to be one single entity, it is actually made up of many small fruits that are clustered together. Each small fruit in the cluster originates from a single ovary of the flower.

An example of an aggregate fruit is a raspberry or a blackberry, where the clustered small fruits can easily be observed.

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Iron is a crucial nutrient for plants due to its involvement in several important biological processes. Let's break these down:

• Aids in the formation of chlorophyll and proteins: Without iron, plants cannot produce chlorophyll, the pigment that gives plants their green color and is essential for photosynthesis, the process through which plants convert sunlight into chemical energy. Additionally, iron is a component of some proteins and enzymes that facilitate various metabolic reactions within the plant.
• Helps in cell division: Iron plays a role in cell division and plant growth by being a part of enzymes that drive the synthesis of DNA. This is vital for the overall development and reproduction of plant cells.


• Protects the plants from pest attack: While iron is not primarily known for its role in pest protection, healthy plants, which benefit from sufficient iron, are generally more resilient to diseases and pests.
• Fastens fruits maturation: A well-functioning plant metabolism, aided by adequate iron levels, ensures that the plant's life cycle progresses timely, allowing fruits to mature at the right time.

In summary, iron is crucial because it is involved in the formation of chlorophyll, proteins, and DNA, all of which are essential for the growth, energy production, and reproduction of the plant. This, in turn, helps the plant grow healthy and resilient.

Which of the following factors can lead to overcrowding?

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To understand overcrowding, we need to consider factors that increase or decrease a population within a certain area.

High natality refers to a high birth rate. When more individuals are born in an area than those leaving it, the population will naturally increase, potentially leading to overcrowding as the area becomes inhabited by more individuals than it can comfortably support. This is because more births without corresponding departures or deaths means more people vying for the same resources.

Emigration is the process of individuals moving out of a given area to live elsewhere. This movement decreases the population of an area, which would typically help prevent overcrowding rather than cause it. Hence, emigration does not lead to overcrowding.

Competition involves individuals or species competing for limited resources such as food, water, or territory. While it does not directly cause overcrowding, high population density due to overcrowding can intensify competition since more individuals fight for the same scarce resources. Thus, competition is more of a consequence rather than a direct cause of overcrowding.

High mortality means a high death rate. This reduces the number of individuals in a population, which works against overcrowding. With more individuals dying, the population decreases or stabilizes, alleviating pressures that lead to overcrowding.

In summary, among the listed factors, high natality is the most significant contributor to overcrowding as it directly increases population size when not matched by increased emigration or mortality.

Use the diagram above to answer the question that follows

The organelle that shows the organism has plant characteristics is

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The organelle that indicates the organism has plant characteristics is the chloroplast. Chloroplasts are essential because they contain chlorophyll, the green pigment crucial for photosynthesis. Photosynthesis is the process by which plants convert light energy from the sun into chemical energy stored in glucose, a type of sugar. This capability to conduct photosynthesis is a key characteristic that differentiates plants from animal cells.

Moreover, plant cells are generally characterized by having an additional cell structure which is the cell wall. The cell wall provides structural support and protection. However, in the context of identifying plant characteristics primarily through organelles, the chloroplast is the distinctive feature.

The part of the flower that develops into seed is

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In the process of flowering and reproduction in plants, the part of the flower that develops into a seed is the ovule. Let me explain this in a simple manner:

Flowers are the reproductive structures of flowering plants. They consist of various parts, each with a specific role in reproduction.

• The ovule is located within the ovary of the flower. During the process of fertilization, the ovule is fertilized by pollen, which contains the male gametes. Once fertilization occurs, the ovule develops into a seed. So, the ovule is the crucial part that, upon receiving pollen, transforms into a seed.
• The petal is not involved in the development of seeds. Petals are usually colorful and are meant to attract pollinators to the flower. They play no role in the development or transformation into seeds.
• The pedicel is the flower stalk that attaches the flower to the plant. It does not participate in seed formation.
• The style is a part of the female reproductive organ, but it serves only as a pathway for pollen tubes to reach the ovary where the ovule is situated. It does not develop into seeds.

Therefore, the correct answer is the ovule, as it is the part that transforms into a seed after fertilization.

Darwin's theory of evolution is based on the principle of 

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Darwin's theory of evolution is based on the principle of natural selection. This concept explains how species change over time in response to their environment.

Here's a simple way to understand it: In any given environment, there are more individuals born than can survive. These individuals vary slightly in their traits, such as color, size, speed, etc. Some of these variations might give an individual a slight edge in the environment, helping them to survive better or reproduce more than others. For example, a faster rabbit might escape predators more successfully than slower ones.

These advantageous traits are more likely to be passed down to the next generation. Over many generations, these beneficial traits become more common in the population. This process is known as natural selection because it "selects" the traits that best suit the environment. Consequently, the species slowly evolves and adapts to their surroundings.

The key point is that natural selection is a gradual process driven by the survival and reproduction of individuals with favorable traits in a specific environment. Unlike the other options, it doesn't rely on the use or disuse of organs, the inheritance of acquired characteristics during an individual's life, or sudden genetic changes known as mutations.

A form of adaptive colouration that helps animals to remain unnoticed is

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A form of adaptive coloration that helps animals to remain unnoticed is called countershading.

Countershading is a type of camouflage where an animal's coloration is darker on the upper side and lighter on the underside. This coloration helps them to blend into their surroundings better, reducing the chance of being seen by predators or prey.

Here's a simple explanation of how it works:

• Upper Side (Darker): The darker color on the top of the animal helps them to merge with the darker environment when viewed from above, such as the forest floor or the deep ocean when viewed from high above.


• Underside (Lighter): The lighter color on the underside helps them blend in with the lighter background when viewed from below, like the sky or the surface of the water illuminated by the sun.

This dual shading effect reduces the animal's shadow and profile, making them less visible and thereby improving their chances of survival. Other terms like hibernation, aestivation, and migration refer to processes that are not directly related to coloration or camouflage. Therefore, countershading is the correct term for adaptive coloration that aids in concealment.

The bacteria in the large intestine of man synthesizes

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The large intestine of humans is home to a diverse community of beneficial bacteria. These bacteria primarily synthesize vitamins, particularly vitamin K and some of the B vitamins, such as B12. They do not typically produce minerals or glucose.

Here's a simple breakdown:

• Vitamins: These are organic compounds that are essential in small quantities for human health. The bacteria in the large intestine help produce certain vitamins that our bodies cannot synthesize efficiently on their own. For example, vitamin K is essential for blood clotting and bone health, and some B vitamins play crucial roles in metabolism and energy production.
• Glucose: While it is a major source of energy for the body, it is not synthesized by intestinal bacteria. Glucose is typically obtained from the digestion of carbohydrates in the diet.
• Amino Acids: These are the building blocks of proteins. Although some bacteria can modify specific amino acids, the primary synthesis and provision of amino acids come from dietary proteins and metabolic pathways within human cells, not directly from bacteria in the large intestine.
• Minerals: These are inorganic elements like calcium and iron that are absorbed from the diet. Bacteria in the intestine can assist in the absorption process but do not synthesize minerals themselves.

Thus, the correct and simplest answer is that the bacteria in the large intestine primarily synthesize vitamins.

Use the diagram above to answer the question that follows

The organ is responsible for

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Since I do not have access to the diagram mentioned, I will explain all the functions listed and how they relate to specific organs. You can then match the explanation with the organ shown in the diagram.

• Production of Heat: This function is typically related to muscles, primarily skeletal muscles. During physical activity, muscles contract and produce heat as a byproduct of metabolism. The liver is another organ involved in heat production through metabolic reactions.
• Osmoregulation: This function is primarily associated with the kidneys. The kidneys help maintain the balance of water and electrolytes in the body by filtering blood and forming urine, thus regulating the body's internal environment.
• Vasoconstriction: This process is often related to blood vessels, particularly the arterial system. It involves the narrowing of blood vessels, which increases blood pressure and reduces blood flow to certain areas. The nervous system, specifically the autonomic nervous system, plays a key role in regulating vasoconstriction.
• Production of Hormones: Many organs are involved in hormone production, including the hypothalamus, pituitary gland, thyroid gland, adrenal glands, pancreas, and reproductive organs. Each of these organs produces specific hormones that regulate various physiological functions in the body.

Identify the organ in the diagram and match it with the corresponding function explained above.

One of the following is a courtship behaviour in animals

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Courtship behavior in animals is a complex set of actions and rituals that animals perform to attract a mate and ensure reproduction. Among the given options, the behavior most directly related to courtship is display.

Why is display a courtship behavior?
A display involves a series of movements, sounds, visual appearances, or other activities performed by animals to attract a mate. These displays are meant to show off the animal's strength, health, genetic quality, and overall suitability as a mate. For example, peacocks spread their colorful feathers to attract peahens, while many bird species might sing or dance.

The purpose of such displays is to communicate information and signals to potential mates, enhancing the chances of successful mating. These displays often indicate the physical and genetic fitness of the individual performing them, allowing potential mates to choose who to pair up with best. Therefore, display is directly associated with attracting mates and is considered a courtship behavior.

Mouth part adapted for piercing and sucking is found in

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The mouth parts adapted for piercing and sucking are found in the mosquito. Mosquitoes have specialized mouthparts known as a proboscis, which is designed to pierce the skin of their hosts and suck blood. This proboscis consists of a long, slender, and flexible tube that can penetrate the skin. Inside the proboscis are several delicate structures that help to hold the host's skin and locate blood vessels, allowing the mosquito to efficiently feed on blood.

In contrast, insects like the housefly have sponge-like mouthparts for lapping up liquids, the grasshopper has chewing mouthparts adapted for eating plants, and the cockroach also has chewing mouthparts suitable for a wide range of foods.

The main excretory product of earthworm is

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The main excretory product of an earthworm is urea, with some ammonia gas also being released.

Earthworm is an annelid whose major excretory products are: Urea ~ 50% , Ammonia ~ 20-40% , Creatinine and other nitrogenous compounds ~ 5%

Uric acid is the main excretory product of birds, reptiles, and some insects. 

The formation of cilia and flagella in living cells is carried out with the help of

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The formation of cilia and flagella in living cells is primarily carried out with the help of centrioles.

In eukaryotic cells, cilia and flagella are long, hair-like structures that extend from the surface of the cell and are responsible for movement. They are made up of microtubules, which are protein structures. The base of a cilium or a flagellum is anchored to a cell by a structure called the basal body.

The basal body is very similar in structure to a centriole. Centrioles are cylinder-shaped organelles found in animal cells and are composed of microtubule triplets. When a cell is ready to produce cilia or flagella, the centrioles migrate to the surface of the cell and become basal bodies by aiding in the assembly and organization of these microtubules.

Therefore, the role of centrioles is crucial because they act as the organizing centers for the microtubule structures that comprise cilia and flagella. Without centrioles, a cell would not be able to form these important structures.

An example of organism that exhibits counter-shading to escape from its predator is 

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An example of an organism that exhibits counter-shading to escape from predators is a fish. Counter-shading is a type of camouflage where an animal has a darker coloration on its upper side and a lighter coloration on its underside.

This adaptation helps fish in two main ways:

1. When viewed from above, the darker top side blends with the dark depths of the water, making it less visible to predators looking down.
2. When viewed from below, the lighter underside blends with the lighter surface of the water, making it less visible to predators looking upwards.

This dual blending effect helps fish to reduce the risk of being detected by predators, enhancing its chances of survival. This strategy is particularly beneficial in open water habitats where there are few places to hide.

A succession that occurs in an area where there are no pre-existing community is called

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A succession that occurs in an area where there is no pre-existing community is called Primary Succession.

To understand this, imagine a barren landscape where life has never existed before, such as a newly formed volcanic island or a region uncovered by a retreating glacier. In such places, there are no soils or organisms present initially. Here’s how it happens:

• Initial Growth: The first organisms, often called pioneer species, start to colonize the area. They are usually hardy organisms like lichens or certain grasses that can survive in such harsh, lifeless conditions.
• Soil Formation: Over time, these pioneer species help break down rocks into soil as they live and die, adding organic material that enriches the soil.
• Arrival of New Species: As the soil develops, it supports more complex plant species, such as shrubs and trees, which, in turn, create habitats for various animal species.
• Development of a Climax Community: Eventually, the area transforms into a stable and mature ecosystem, known as a climax community, which can sustain a diverse range of life.

In summary, primary succession describes the process of life gradually establishing itself from scratch in an environment that starts with no life or soil, forming an ecosystem over time.

Bilateral symmetry,cylindrical bodies and double openings are characteristic features of

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The features you mentioned, namely bilateral symmetry, cylindrical bodies, and double openings, are characteristic of nematodes.

Let's break it down further:

• Bilateral Symmetry: This means that if you draw a line down the middle of the organism, both halves will be mirror images of each other. Nematodes exhibit this kind of symmetry, which is quite common in more complex organisms as it allows for streamlined movement and efficient sensory processing.


• Cylindrical Bodies: Nematodes have long, tube-like bodies that look like a cylinder. This shape helps them move efficiently through their environment, which can be soil, water, or as parasites inside other organisms.


• Double Openings: Unlike some simpler organisms, nematodes have a complete digestive system with a mouth at one end and an anus at the other, allowing for more efficient digestion and nutrient absorption.

In contrast:

• Hydra: These primarily show radial symmetry and have a single opening for both intake and excretion.


• Protozoa and Protists: These are generally single-celled organisms and do not exhibit all three characteristics mentioned (bilateral symmetry, cylindrical bodies, and double openings). They have more varied body plans and structures.

Therefore, based on these descriptions, nematodes clearly align with the features of bilateral symmetry, cylindrical bodies, and double openings.

Which of the following processes releases oxygen to the atmosphere?

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In the context of releasing oxygen to the atmosphere, only one of the processes you've listed does this: photosynthesis. Let me explain it in a simple way.

Photosynthesis is a process carried out by plants, some bacteria, and algae. These organisms use sunlight, carbon dioxide, and water to create their food, which is a form of sugar. As a byproduct, they release oxygen into the atmosphere. During this process, chlorophyll, the green pigment in plant cells, captures light energy, and helps convert it into chemical energy.

None of the other processes release oxygen:

- Respiration is a process in which living organisms, including plants and animals, take in oxygen and use it to convert glucose into energy, producing carbon dioxide and water as byproducts.

- Combustion involves burning substances, typically in the presence of oxygen, usually resulting in the production of carbon dioxide, water, and energy (heat and light). It does not release oxygen; rather, it consumes oxygen.

- Decomposition is the breakdown of dead organic matter by microorganisms. During this process, organic matter is converted back into carbon dioxide, methane, and other compounds, but it does not release oxygen.

So, the process that releases oxygen into the atmosphere is photosynthesis.

The rhizoid of liverwort is

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The rhizoid of liverwort is unicellular and unbranched.

Here's a simple explanation: Liverworts are a type of non-vascular plant that have structures called rhizoids. These rhizoids look like tiny hairs and they help the plant attach to surfaces like rocks or soil. Even though they help with attachment, they do not have the complexity of true roots.

In liverworts, these rhizoids are formed as single cells, which means they are unicellular. Think of them as being like a single long cell that looks like a hair. This single-celled structure is unbranched, meaning it doesn't split or divide into more parts or sections.

In summary, liverwort rhizoids are unicellular and unbranched, helping them secure the plant to various surfaces without forming complex root structures.

The total number of ATP produced during glycolysis is

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Glycolysis is the process through which one molecule of glucose is broken down into two molecules of pyruvate, and this process occurs in the cytoplasm of the cell. During glycolysis, two different phases are involved: the energy investment phase and the energy payoff phase. Let's break it down:

Energy Investment Phase: At the start of glycolysis, the cell uses 2 ATP molecules. This phase is necessary to modify the glucose molecule and prepare it for the subsequent reactions.

Energy Payoff Phase: As glycolysis continues, 4 ATP molecules are produced. These ATP molecules are formed when certain intermediates donate phosphate groups to ADP (adenosine diphosphate) to form ATP.

Hence, the net gain of ATP during the glycolytic process is calculated by subtracting the ATP used in the Energy Investment phase from those produced in the Energy Payoff phase.

The calculation is as follows:
ATP Produced = 4 molecules
ATP Used = 2 molecules
Net Gain = 4 - 2 = 2 molecules

Therefore, the total number of ATP produced during glycolysis, when considering the net gain, is 2 molecules of ATP.

One of the components of xylem tissue is

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One of the components of xylem tissue is the tracheid.

Let me explain this in simple terms:

The xylem is a type of plant tissue that is crucial for transporting water and nutrients from the roots to the rest of the plant. It plays a key role in plant hydration and nutrition.

Tracheids are long, tubular cells found within the xylem tissue. Their primary function is to help in the transport of water and minerals. Tracheids have thick walls and are dead at maturity, meaning they are hollow and create a continuous network for water flow. This structural arrangement also helps support the plant, providing rigidity and strength.

So, in summary, tracheids are an essential component of xylem tissue because they facilitate the movement of water and provide mechanical support.

The feeding relationship between ruminants and the bacteria in their digestive tract is

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The feeding relationship between ruminants and the bacteria in their digestive tract is symbiotic. In this type of relationship, both the ruminants and the bacteria benefit from each other.

Here's how it works:

• Ruminants are animals such as cows, sheep, and goats. They consume a lot of plant materials, primarily grass, which is rich in cellulose. However, these animals cannot digest cellulose on their own.
• The bacteria living in their digestive tract, particularly in the rumen, help by breaking down cellulose into simpler compounds like fatty acids, which the ruminant can then absorb and use for energy.
• In return, these bacteria benefit by living in a warm and nutrient-rich environment where they can grow and multiply.

This mutual benefit showcases a symbiotic relationship, where both organisms support each other's survival and wellbeing.

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The main excretory products of plants during metabolism are carbon dioxide, excess water, and nitrogenous compounds.

Plants produce carbon dioxide as a metabolic waste product during respiration, while oxygen is a metabolic waste product from photosynthesis. Excretion of gaseous waste in plants takes place through stomatal pores on leaves. Oxygen released during photosynthesis is used for respiration while carbon dioxide released during respiration is used for photosynthesis.

In vascular plants, xylem tissue is responsible for

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In vascular plants, the xylem tissue is primarily responsible for the transportation of water. The xylem functions like a network of tubes spreading throughout the plant, from the roots up to the leaves. Its main role is to carry water and dissolved minerals absorbed from the soil by the roots to other parts of the plant. This movement of water is crucial for maintaining plant health as it supports essential processes like photosynthesis and nutrient distribution. Unlike other tissues, xylem is specifically adapted for this task, with its elongated, tube-like structures which provide an effective passage for water movement.

One of the following is an example of discontinuous variation

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Discontinuous variation refers to variations where the traits are distinct and categorical, meaning individuals can be grouped into distinct categories with no intermediate states. A good example of **discontinuous variation** from the options provided is **blood group**. This is because blood groups are distinct categories (e.g., A, B, AB, O) and individuals belong to one category without any intermediate states.

In contrast, other traits like **shape of the head**, **body complexion**, and **pointed nose** often show a range of variations that are continuous, meaning these traits can have many intermediate forms and cannot be easily categorized into discrete categories. Therefore, **blood group** is an **example of discontinuous variation** because it consists of clearly defined and non-overlapping categories.

The schlerenchyma tissues consist of

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Schlerenchyma tissues are a type of plant tissue known for providing structural support. These tissues are composed of cells that are typically dead at maturity. The cell walls of schlerenchyma tissues are thickened with lignin, which makes them rigid and strong. These characteristics help in supporting the plant body and protecting the plant against external mechanical forces.

To clarify, let's consider the types of cells mentioned:

• Dead Cells: Schlerenchyma tissues consist predominantly of these, as the cells are dead at maturity and filled with lignin.
• Living Cells: These are not characteristic of schlerenchyma tissues. Living cells are more associated with other tissue types, like parenchyma.
• Tracheid Cells: These are specific types of conducting cells in the xylem part of vascular plants, which are different from schlerenchyma.
• Meristematic Cells: These are undifferentiated cells that are capable of division, found in growth regions of plants, unlike the hardened structure of schlerenchyma.

In summary, schlerenchyma tissues consist mainly of dead cells. Their primary role is structural support, making them distinct from tissues composed of living cells, tracheid cells, or meristematic cells.

The transmission of diseases through contamination of food is an economic importance of

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The transmission of diseases through contamination of food is an economic importance primarily related to cockroaches.

Cockroaches are considered pests that thrive in unsanitary environments. They are known to carry various pathogens, such as bacteria, viruses, and parasites, on their bodies and in their droppings. When they come into contact with food, they can contaminate it, leading to foodborne diseases.

This contamination can have several economic impacts:

• Health Care Costs: People who consume contaminated food may fall ill, leading to medical expenses for treatment and care.
• Workplace Productivity: Sick employees may need to take time off work, affecting productivity and economic output.
• Restaurant and Business Reputation: Establishments found to have unsanitary conditions due to cockroach infestations can face loss of customers, declining sales, and potential closure.
• Regulatory Fines: Businesses may incur fines or penalties from health and safety agencies if they fail to control cockroach infestations.

Therefore, managing and preventing cockroach infestations is crucial to safeguarding public health and protecting economic interests associated with food safety.

After fertilization in plants, the zygote develops into

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After fertilization in plants, the zygote develops into an embryo. This process is a critical stage in the life cycle of a plant. Let me explain it in simple steps:

• When a pollen grain fertilizes an ovule, the male gamete (sperm) unites with the female gamete (egg cell) within the ovule, leading to the formation of a zygote.
• The zygote is the first cell of the new plant, and it will initially undergo a series of mitotic cell divisions. As it divides and grows, it transforms into a small, multicellular structure known as the embryo.
• The embryo is essentially the young plant encased within the protective environment of the seed, and it will later develop into the mature plant.

Therefore, after fertilization, the focus on growth centers around the development of the embryo, which is a crucial step in the successful reproduction and life cycle continuation of plants.