JAMB UTME - Biology - 2024

A trait that is always expressed during crossing of hereditary characteristics is

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When discussing the crossing of hereditary characteristics, a trait that is always expressed is known as a dominant trait. In genetics, traits are determined by genes, and each trait has two alleles, one from each parent. Alleles can either be dominant or recessive.

Dominant traits are those that are expressed in the organism's phenotype when at least one allele for the trait is dominant. This means that even if the organism has one dominant and one recessive allele for a trait, the dominant trait will take precedence and be observed in the individual.

Conversely, a recessive trait is only manifested in the phenotype if both alleles for that trait are recessive. Therefore, when a dominant allele is present, it will mask the expression of a recessive allele, resulting in the dominance of the trait in question.

For example, if a plant has one allele for tall height (dominant) and one for short height (recessive), the plant will appear tall because the tall allele is dominant.

Which of these is a respiratory organ in mammals?

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The organ responsible for respiration in mammals is the lungs. The lungs are located in the chest cavity and are essential for breathing. Here's a simple explanation:

• The lungs allow mammals to take in oxygen from the air and expel carbon dioxide, which is a waste product of the body's metabolism.
• Air enters the body through the nose or mouth and travels down the trachea to reach the lungs.
• Inside the lungs, the air travels through smaller and smaller passages called bronchi and bronchioles, eventually reaching tiny air sacs known as alveoli.
• The alveoli are where the exchange of gases occurs: oxygen passes from the air into the bloodstream, and carbon dioxide moves from the blood into the alveoli to be breathed out.

The other options mentioned are not used for respiration in mammals:

• The skin is primarily an organ for protection. It acts as a barrier against physical damage, pathogens, and dehydration.
• The mouth is involved in breathing but is not the primary organ for gas exchange. It is part of the pathway for air and also plays a role in digestion.
• The heart is a muscle that pumps blood throughout the body. It is an essential component of the circulatory system, but it is not directly involved in the respiratory process.

The major building block of an organism is...

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The major building block of an organism is Carbon. Let me explain why:

1. Backbone of Organic Compounds: Carbon is the fundamental component in organic compounds, which form the basis of all living organisms. This includes carbohydrates, proteins, lipids, and nucleic acids (DNA and RNA). These molecules are crucial for the structure and function of cells.

2. Versatile Bonding: Carbon atoms can form four covalent bonds with other atoms. This allows carbon to form a diverse array of molecules, ranging from simple methane (CH₄) to complex macromolecules like proteins and nucleic acids.

3. Stability: Carbon-based molecules are stable and can exist in various forms. This stability is critical for building compounds that are integral to life.

4. Flexibility in Forming Structures: Carbon chains can form rings, long chains, and branched formations, providing structural diversity that supports the complex needs of living organisms.

While elements like nitrogen, oxygen, and hydrogen are also essential, carbon's unique ability to bond in multiple and versatile ways is why it is considered the backbone of life. Hence, we often refer to life as "carbon-based."

The part of the inner ear that is responsible for hearing is

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The part of the inner ear that is responsible for hearing is the cochlea.

The cochlea is a spiral-shaped, fluid-filled structure that looks a little like a snail shell. Its primary function is to convert sound waves from the air into electrical signals that can be interpreted by the brain as sound. Here's how it works:

• Sound waves enter the ear canal and cause vibrations in the ear drum.
• These vibrations are transmitted through the tiny bones in the middle ear and reach the cochlea in the inner ear.
• Inside the cochlea, the vibrations cause the fluid to move, which in turn moves tiny hair cells located on a structure known as the basilar membrane.
• The movement of these hair cells produces electrical signals.
• The electrical signals are then sent to the brain via the auditory nerve, where they are interpreted as sound.

Thus, the cochlea plays an essential role in the process of hearing by transforming sound vibrations into nerve impulses that the brain can understand.

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Use the diagram above to answer the question that follows

The diagram above is

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The circulatory system is a network of blood vessels, the heart, and blood that moves throughout the body. The circulatory system's main function is to transport nutrients, oxygen, and hormones to the body's cells, and remove waste products. 

The reproductive system is a collection of organs in both males and females that work together to produce offspring, primarily consisting of the gonads (ovaries in females, testes in males) which create sex cells (eggs and sperm), and accessory organs that transport and nurture these cells to facilitate fertilization and potential pregnancy.

The nervous system is a complex network of nerves and nerve cells (neurons) that control bodily functions by sending signals between the brain and the rest of the body, allowing us to move, think, feel, and regulate internal processes; it consists of two main parts: the central nervous system (brain and spinal cord) and the peripheral nervous system

The urinary system helps the body maintain balance by removing waste products like urea, extra salt, and extra water. Urea is a waste product created when the body breaks down protein from foods like meat, poultry, and some vegetables. Its function is to remove waste from the body through urine bladder, urethra, kidneys and ureters.

Parts of the urinary system 

• Kidneys: Two bean-shaped organs located in the middle back, under the ribs. They filter blood to remove waste and extra water.
• Ureters: Two tubes that carry urine from the kidneys to the bladder.
• Bladder: A hollow organ in the pelvis that stores urine. When the bladder is full, it signals the body to urinate.
• Urethra: A small tube that carries urine from the bladder out of the body.

The urinary tubules opens into a proximal convoluted tubule coils to form distal by making a

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The urinary tubules are part of the nephron, which is the basic functional unit of the kidney. Each nephron has several segments, including the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule, and the collecting duct.

After the proximal convoluted tubule, the nephron forms a loop known as the loop of Henle. This loop dips down into the medulla of the kidney and is crucial for concentrating urine and maintaining water balance. The form that this loop takes is best described as a U-shaped loop. This shape is because the loop of Henle descends, makes a turn, and then ascends, forming a ‘U’ as it transitions eventually into the distal convoluted tubule.

Therefore, the correct description of the transition from the proximal convoluted tubule to the distal convoluted tubule, via the loop of Henle, is through a U-shaped loop.

Which of the following evidences of evolution employs the use of radio-isotope dating?

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The evidence of evolution that employs the use of radio-isotope dating is fossil records.

Let me explain this further. Fossils are the preserved remains or traces of organisms that lived in the past. Scientists use fossils to understand the history of life on Earth and how species have changed over time. But to make meaningful conclusions, they need to know the age of these fossils.

This is where radio-isotope dating comes into play. Radio-isotope dating, also known as radiometric dating, is a technique used to determine the age of rocks and fossils. It measures the decay of radioactive isotopes in materials.

Here's a simple way to understand it: you can think of radioactive isotopes as tiny clocks contained within rocks and fossils. These isotopes decay at a constant rate over time. By measuring the amount of remaining isotopes and knowing their half-life (the time it takes for half of the isotopes to decay), scientists can calculate how long the isotopes have been decaying. This gives them the age of the fossil or rock, helping to place it in the context of Earth's history.

In conclusion, fossil records are the evidence of evolution that utilize radio-isotope dating to provide a time frame and chronological context for evolutionary events.

A discontinuous morphological variation often used in crime detection is the

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In crime detection, the most popular discontinuous morphological variation used is finger prints.

Here's a simple way to understand why:

Defining Morphological Variation: Morphological variation refers to differences in the form and features of living organisms. A variation is termed as 'discontinuous' when it falls into distinct categories with no intermediates. For example, you either have a particular feature or you don't.

Why Fingerprints are Discontinuous: Fingerprints are a good example of discontinuous variation because each individual's set of fingerprints is unique. There are no gradual transitions – you either have a specific fingerprint pattern, like a loop, whorl, or arch, or you don't.

Application in Crime Detection: Because everyone has a unique set of fingerprints and these can be easily left on surfaces, fingerprints are a powerful tool in crime detection. Investigators gather fingerprint evidence from crime scenes and compare them with fingerprint databases to identify suspects.

In conclusion, the use of fingerprints lies mainly in their uniqueness and distinctiveness, making them crucial for identifying individuals in forensic investigations.

Use the diagram above to answer the question that follows

The experiment is set up to determine the presence of

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Chlorophyll: Experiments related to chlorophyll typically involve leaves and light exposure to understand photosynthesis. You might see diagrams showing a leaf that is partially covered with foil to demonstrate which parts of the leaf perform photosynthesis.

Starch: To test for the presence of starch, particularly in plants, an experiment usually involves boiling a leaf in water, then in alcohol, and finally treating it with iodine solution. The presence of starch is confirmed by a blue-black color change.

Oxygen: Experiments designed to detect oxygen often involve aquatic plants like Elodea. When the plant is exposed to light, bubbles or gases released would indicate photosynthetic activity, releasing oxygen.

Pigment: Pigment experiments often relate to chromatography, where pigments are separated on a medium like paper. These are used to study various pigments present within plant tissues.

The part of the brain that receives sensory impulses of smell is the

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The part of the brain that receives sensory impulses of smell is the olfactory lobe. When you perceive a scent, information from the nose's sensory cells is sent to the olfactory lobe, and it is here that the brain begins the process of identifying the fragrance. The olfactory bulb is the first region that processes smell sensory data, allowing you to discern various odors. Other parts of the brain, like the cerebrum, help process and associate these smells with memories or emotions, but the olfactory lobe is the initial receiver of these sensory signals related to smell.

Bryophyte is an intermediate group between higher algae and 

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Bryophytes are an intermediate group between higher algae and pteridophytes. Let's break this down to understand why.

Bryophytes include plants like mosses and liverworts. They are often referred to as the simplest form of land plants because they are non-vascular, meaning they do not have specialized tissues, like xylem and phloem, for water and nutrient transport. Instead, they rely on diffusion, which limits their size and requires them to live in moist environments.

On the other hand, pteridophytes are a group of plants that include ferns and are the next step up in complexity from bryophytes. They are important in this context because they mark the transition from non-vascular bryophytes to vascular plants (plants with vascular systems).

Why is this important? This transition is crucial because it represents the evolution of plants from simple, water-dependent organisms to more complex and diverse forms that can live in a wider range of environments, thanks to their vascular systems.

In summary, bryophytes serve as an evolutionary bridge between the simpler algae and the more complex pteridophytes due to their similarities and differences in structure and reproduction.

Use the diagram above to answer the question that follows

The part labelled III is

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The diagram provided is not visible since this is a text-based interface. However, I can help explain the parts of an insect as they typically relate to the given options: abdomen, head, maxillae, and thorax. Typically, insects have three main body parts: the head, the thorax, and the abdomen. The maxillae are a part of the mouthparts, usually located on the head. Here is a simple explanation of these parts:

Head: The head is the front part of the insect's body where the eyes, antennae, and mouthparts, such as the maxillae, are located. It is the center for sensory input and feeding.

Thorax: Located just behind the head, the thorax is the middle section of an insect's body. It is where the legs and wings (if present) are attached. It contains muscles that help in movement.

Abdomen: The abdomen is the rear part of an insect's body. It contains vital organs such as those for digestion, excretion, and reproduction. It is generally more flexible than the thorax.

Maxillae: The maxillae are a part of the insect's mouthparts and are found on the head. They assist in manipulating food.

Based on the given options, if Part III is a section of an insect's body segmented into three prominent parts, it usually corresponds to the thorax or abdomen. Without the diagram, a precise answer cannot be given, but based on typical labeling, Part III is often referring to the middle segment; hence, the thorax is a likely match.

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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.

Bile is a greenish alkaline liquid which is stored in the

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Bile is a greenish alkaline liquid that plays a crucial role in the digestion of fats. It is produced by the liver and contains bile acids, which are essential for emulsifying fats, making them easier for enzymes to break down. Once bile is produced by the liver, it is not immediately released into the digestive tract. Instead, it is stored and concentrated in the **gall bladder**. The gall bladder is a small, pouch-like organ located just beneath the liver. It stores bile until it is needed, typically after eating, when it is then released into the small intestine to aid in digestion.

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.

A community with a population of two million three hundred and ten thousand people living in an area of two thousand three hundred and ten square kilometres has a population density of

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To calculate the population density of a region, you need to divide the **total population** by the **area** they are living in. This will give you the number of people per unit area, typically per square kilometer in this case.

Given:

• Total population: 2,310,000 people
• Area: 2,310 square kilometers

The formula for population density is:

Population Density = Total Population / Area

By plugging in the given values:

Population Density = 2,310,000 / 2,310 = 1,000

This means there are **1,000 people per square kilometer** in this community. Therefore, the correct population density is **1,000**.

The common examples of trees found in the desert are

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Deserts are characterized by their arid conditions, meaning they receive very little rainfall throughout the year. To survive in such environments, plants need special adaptations. Among the plant varieties, the trees commonly found in deserts include **cacti** and the **baobab tree**. Here's a brief explanation of why these trees are well-suited to desert environments:

• Cacti: Cacti are well-known for their ability to store water. They have thick, fleshy stems that retain water, allowing them to survive long periods of drought. Additionally, cacti have spines instead of leaves. Not only do these spines offer protection, but they also reduce water loss by minimizing the surface area exposed to the harsh desert sun.
• Baobab Trees: Baobabs are distinct because of their massive trunks, which can store large quantities of water—essential for enduring extended dry periods in desert locales. Their ability to thrive in arid regions stems from this water storage feature, making them symbols of resilience in the desert habitat.

Plants like **raffia palm**, **coconut**, **white and red mangrove**, and **shea-butter** trees are not typically found in desert environments because they require more moisture and different soil conditions compared to the harsh, dry lands of the desert.

The abiotic factor that affect the population growth of an organism is

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The term abiotic factors refers to the non-living components of an environment that can influence the growth and survival of organisms. In the given options, the factor that qualifies as an abiotic factor is rainfall. Abiotic factors are different from biotic factors, which involve living things such as predators, food availability, and diseases.

Explanation:

1. **Rainfall**: This is the only abiotic factor mentioned in the list. Rainfall provides water, which is essential for the survival of most organisms. It affects the availability of water resources, which are crucial for hydration of plants and animals, as well as for maintaining aquatic habitats. The amount, timing, and distribution of rainfall can influence the growth of plant populations, which in turn affects the availability of food and shelter for other organisms.

2. **Predator**: This is not an abiotic factor. Predators are living organisms that can directly influence the population of prey species by hunting and consuming them. This is a biotic interaction.

3. **Food Shortage**: Food availability is related to living organisms and is considered a biotic factor. Food shortage directly affects the survival and reproduction of organisms that depend on that food source.

4. **Disease**: This is again a biotic factor. Diseases are caused by pathogens, which are living organisms such as bacteria, viruses, or fungi, and they can spread among populations, reducing their size and growth.

In summary, rainfall is the abiotic factor from the choices given, and it plays a critical role in the environment by influencing water availability and ecosystem balance.

Infectious diseases are caused by

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Infectious diseases are illnesses caused by certain harmful microorganisms that invade the body. These microorganisms can be grouped into several categories. Among these categories, two of the most notable are bacteria and protozoa. Both of these groups contain species that can lead to disease.

Bacteria are single-celled microorganisms. While many bacteria are harmless or even beneficial to humans, some can cause diseases such as strep throat, tuberculosis, and urinary tract infections. Bacteria are living organisms that reproduce by themselves, and they can sometimes produce toxins that harm the host.

Protozoa are a diverse group of single-celled organisms that live in a variety of moist or aquatic environments. Many protozoa are harmless, but some can cause serious diseases. For example, the protozoan parasite Plasmodium causes malaria, a serious disease transmitted by mosquitoes.

Protists is a broader term that includes protozoa as well as algae and fungi-like organisms, and while not all protists cause disease, the term could refer to certain disease-causing protozoans.

Amoebas are a type of protozoan characterized by their changing shape and movement. Although many amoebas are harmless, some types, such as Entamoeba histolytica, cause illnesses like amoebic dysentery, which is characterized by diarrhea and stomach pain.

In summary, infectious diseases can be caused by bacteria and a variety of protozoa, including specific types like amoebas. Understanding these different microorganisms helps in diagnosing and treating the diseases they cause.

Use the diagram above to answer the question that follows:

Recombination of genes at fertilization is represented by the part labelled

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During prophase I, homologous chromosomes from each parent pair up and exchange genetic material, a process known as crossing over. This process creates new combinations of genes in the resulting gametes. When two gametes unite during fertilization, the offspring will have a unique combination of DNA.

Genetic recombination during fertilization takes place in the prophase I stage of meiosis ( part labelled III)

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.

Reproduction in paramecium is by

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Paramecium is a single-celled organism that belongs to the group of protists known as ciliates. The primary method of reproduction in paramecium is through binary fission. Let's break down what that means:

Binary Fission: This is a type of asexual reproduction, which means it does not involve the fusion of gametes (sperm and egg). Instead, it is a simple division process in which the organism creates a copy of itself. Here is how it works in paramecium:

• The paramecium first duplicates its genetic material, which is contained within its nucleus. During this process, the genetic information is doubled to ensure that each new cell has the same DNA as the parent cell.
• Once the DNA is replicated, the paramecium's cell elongates, making it ready to split.
• Next, the cell divides into two almost equal halves. Each new cell, or daughter cell, receives a copy of the original genetic material.
• Finally, these daughter cells grow to the size of the original parent cell and the process can begin again.

This process of binary fission allows paramecia to reproduce quickly and efficiently, leading to exponential population growth under favorable conditions. Unlike other methods like budding, spore formation, or fragmentation, binary fission is a straightforward division of the cell into two identical parts.

Conclusion: Paramecium reproduces mainly by binary fission, a type of asexual reproduction that results in two genetically identical offspring from a single parent organism.

If the F1 generation allows for self-pollination, what will be the genotypic ratio of the offspring?

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To determine the genotypic ratio of the offspring when the F1 generation allows for self-pollination, first understand the process of Mendelian genetics. In a typical monohybrid cross, let's assume two homozygous parents, one dominant (AA) and one recessive (aa). When these two are crossed, the F1 generation will all have the genotype Aa, which is heterozygous.

If we allow the F1 generation (Aa) to self-pollinate, crossing Aa with Aa, the potential genotypes of the offspring can be determined using a Punnett square:

From this Punnett square, you can see the possible combinations:

• 1 AA
• 2 Aa
• 1 aa

Thus, the genotypic ratio of the offspring is 1 : 2 : 1, which represents one homozygous dominant (AA), two heterozygous (Aa), and one homozygous recessive (aa).

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.

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The first organisms on Earth are widely believed to have evolved from aquatic habitats. This conclusion is based on several scientific observations and theories.

1. **Early Earth Conditions:** When Earth was still a young planet, conditions were harsh, with a very hot climate and volcanic activity. During this time, the planet's surface was largely covered by oceans which provided a stable environment where simple life forms could potentially thrive. The presence of water is essential because it acts as a medium for chemical reactions and life-supporting processes.

2. **Chemistry of Life:** Water is a solvent that facilitates the necessary chemical reactions required for life. In aquatic environments, organic molecules could dissolve in water, leading to complex chemical reactions, leading to the formation of proteins, lipids, and nucleic acids, which are building blocks of life.

3. **Abiogenesis and the "Primordial Soup" Theory:** One theory of how life began is called the "primordial soup" theory, which suggests that life originated through chemical reactions in the ocean. This soup-like mixture of organic compounds provided the ideal conditions for the first living organisms to form.

4. **Evidence from Fossils:** The oldest known fossils are those of simple microorganisms such as bacteria. These fossils have been found in ancient sedimentary rocks, which were formed in water.

In summary, while there are different types of habitats available on Earth now, the initial conditions billions of years ago favored the formation of life in an aquatic environment. Therefore, it is widely accepted that the earliest life forms evolved in the aquatic habitat.

Use the diagram to answer the question that follows

The flower of plants belongs to part labelled

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The flower is the reproductive organ of a plant. It is a plant organ, which is defined as a group of tissues that work together to perform a specific function. 

The process by which plants loss water to the atmosphere is

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The process by which plants lose water to the atmosphere is referred to as transpiration. Let's break this down:

Transpiration is the process where water absorbed by plant roots is eventually released into the atmosphere as water vapor through the plant's leaves. This primarily occurs through small openings on the leaves known as stomata.

Here's how it happens:

• First, water is absorbed by the plant roots from the soil. This water moves up through the plant through structures known as xylem vessels.
• The water then reaches the leaves, where it helps in a vital process called photosynthesis. Excess water, however, evaporates into the atmosphere through the stomata.

Transpiration is crucial for plants because it not only helps them get rid of excess water but also plays a significant role in cooling the plant and enabling the upward movement of essential nutrients from the soil. It also contributes to the water cycle by adding moisture to the atmosphere.

In summary, transpiration is an essential process where plants lose water to the atmosphere, playing an important role in plant health and environmental equilibrium.

Cell division that involves the growth, development, repairs and replacement of worn out tissues is

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The type of cell division that involves the growth, development, repair, and replacement of worn-out tissues is mitosis.

Mitosis is a process by which a single cell divides to produce two identical daughter cells. This process is crucial for several reasons:

• Growth: As an organism develops, it needs more cells to increase in size. Mitosis ensures that new cells are genetically identical to the original cell, allowing tissues to expand properly.
• Development: During an organism's lifecycle, cells must differentiate and divide to form different tissues and organs. Mitosis provides the mechanism for such divisions while maintaining genetic consistency across cells.
• Repair: If tissues are damaged, mitosis allows for the production of new cells to replace the damaged or dead ones, helping tissues to heal.
• Replacement of Worn-Out Cells: Cells naturally wear out over time. Mitosis allows for their continuous renewal, ensuring that tissues function properly and maintain their integrity.

The process involves several phases, including prophase, metaphase, anaphase, and telophase, each contributing to the accurate duplication and distribution of chromosomes to the daughter cells.

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.

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Inbreeding is highly discouraged in humans primarily because it can greatly increase the risk of hereditary diseases. When close relatives, who may share similar genetic traits, have children together, there is a higher probability that both parents carry the same recessive genes. These recessive genes could cause genetic disorders if inherited in pairs. In an outbred population, these recessive genes are less likely to pair up, thereby reducing the risk of such disorders.

Hereditary diseases include conditions like cystic fibrosis, sickle cell anemia, and Tay-Sachs disease. These diseases can cause severe health problems and affect the quality of life of those born with them. The higher genetic similarity between parents who are closely related increases the chances of these diseases manifesting in their offspring.

In addition, inbreeding can also lead to the phenomenon known as "inbreeding depression," which can cause a reduction in fertility, survivability, and growth rates due to the accumulation of deleterious alleles. This can contribute to an increased death rate of newborns or result in other developmental concerns.

In summary, inbreeding increases the likelihood of harmful genetic conditions being expressed and can significantly impact the health and survival of the offspring, which is why it is strongly discouraged in human societies.

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.

The number of vertebrae in the human vertebral column is

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The human vertebral column, also known as the spine or backbone, consists of a series of bones called vertebrae. These vertebrae are stacked on top of each other and are categorized into different regions. There are a total of 33 vertebrae in the human vertebral column.

Here's a simple breakdown:

• 7 cervical vertebrae: These are located in the neck region. The first two are known as the atlas and axis, which are specialized to allow for head movement.
• 12 thoracic vertebrae: These are located in the upper and mid-back, connecting to the ribs and forming part of the thoracic cage.
• 5 lumbar vertebrae: These are found in the lower back and are the largest and strongest, supporting much of the body's weight.
• 5 sacral vertebrae: These are fused together to form the sacrum, a triangular-shaped bone at the base of the spine, which forms part of the pelvis.
• 4 coccygeal vertebrae: These form the coccyx or tailbone, and are usually fused together.

Therefore, when you add up these vertebrae (7 cervical + 12 thoracic + 5 lumbar + 5 sacral + 4 coccygeal), you get a total of 33 vertebrae in the human vertebral column. It's important to note that while the sacral and coccygeal vertebrae are often fused together, they are still counted separately when totaling the number of vertebrae.

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.

In glycolysis, glucose is broken down through series of reactions in the presence of enzyme and absence of oxygen to produce

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Glycolysis is a biochemical process through which glucose, a six-carbon sugar, is broken down into two molecules of a three-carbon compound called **pyruvic acid** or **pyruvate**. This process occurs in the **absence of oxygen** and is also referred to as anaerobic respiration. During glycolysis, energy stored in glucose is released, and a net gain of **two molecules of ATP (adenosine triphosphate)** is produced, which serves as a direct energy source for cellular activities.

Here is a brief explanation of the main steps involved in glycolysis:

• Glucose is first phosphorylated and converted into different sugar intermediates through a series of enzyme-catalyzed reactions.
• These intermediates are then further processed to form **two molecules of pyruvic acid**.
• During these steps, energy in the form of ATP is produced. In total, four molecules of ATP are generated, but two of these are used up in the initial steps, leading to a **net gain of two ATP molecules.**
• The process also produces two molecules of NADH, another energy carrier, which could be utilized in other pathways if oxygen is available.

In summary, during glycolysis in the absence of oxygen, glucose is transformed into **pyruvic acid and a net gain of ATP molecules**, making the answer **pyruvic acid + ATP**.

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 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.

How many chromosomes will be present in a gamete if the somatic cell has 8 chromosomes?

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In humans and many other organisms, there are two types of cells: **somatic cells** and **gametes**. **Somatic cells** are typical body cells and are **diploid**, meaning they contain two sets of chromosomes—one set from each parent. **Gametes** are reproductive cells (sperm and egg) and are **haploid**, meaning they contain only one set of chromosomes.

In this context, if a **somatic cell** has **8 chromosomes**, it means it is carrying two complete sets of 4 chromosomes each. In order to form a **gamete**, this diploid number must be reduced to a **haploid number** through the process of **meiosis**.

Therefore, the **number of chromosomes** in a **gamete** would be **half** the number of chromosomes in a **somatic cell**. This is because gametes need to have just one set of chromosomes to ensure that when two gametes meet during fertilization, they create a diploid organism.

Thus, if the **somatic cell** has **8 chromosomes**, each **gamete** will have **4 chromosomes**.

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.

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The central nervous system (CNS) is a crucial part of the overall nervous system in the body, responsible for processing information and controlling most functions of the body and mind. It comprises the brain and the spinal cord.

1. Brain: The brain is the control center of the CNS. It is responsible for interpreting sensory information, coordinating movement, and managing functions such as thoughts, emotions, and memories. The brain oversees all voluntary and involuntary actions.

2. Spinal Cord: The spinal cord acts like a communication highway, transmitting signals between the brain and the rest of the body. It is essential for reflex actions and relays messages to and from the brain.

Together, the brain and spinal cord make up the central nervous system. Without this system, the body would not be able to respond appropriately to stimuli or maintain homeostasis. Thus, the correct components of the central nervous system are the brain and spinal cord.

The part of the kidney where the selective reabsorption takes place is

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The part of the kidney where selective reabsorption takes place is the Henle's loop, also known as the Loop of Henle.

Here's a simple explanation:

The kidneys are responsible for filtering blood, removing waste, and balancing bodily fluids. This is accomplished through structures called nephrons, each of which functions like a tiny processing plant. A nephron comprises various parts, including the glomerulus, Bowman's capsule, and the Loop of Henle.

Initially, blood is filtered in the glomerulus, and the resulting fluid then enters the Bowman's capsule. However, this fluid contains essential nutrients and ions that our body needs. Therefore, it must be reabsorbed back into the bloodstream.

The Loop of Henle plays a critical role in this reabsorption process. It creates a concentration gradient that allows water, sodium, chloride ions, and other substances to be reabsorbed selectively into the blood. This ensures that vital nutrients and electrolytes are not lost in the urine.

The Henle's loop is integral in forming concentrated urine, enabling the body to conserve water and important nutrients while still eliminating waste effectively. Thus, it is the site where selective reabsorption primarily occurs.