Explanation:

The correct answer is: C. Homeostasis

Homeostasis means the ability of an organism to keep its internal conditions stable, even when the outside environment changes.

Here's why the other answers are incorrect:

• A. Diuresis: This refers to the process of producing urine, not maintaining internal stability.
• B. Endosmosis: This is the movement of water into a cell, not the ability to maintain balance inside the body.
• D. Plasmolysis: This is the shrinking of a cell when it loses water, not the process of maintaining internal balance.

Explanation:

The correct answer is: C. Maize

Maize (corn) has parallel venation in its leaves. This is a feature of monocot plants. In parallel venation, the veins run in straight, parallel lines. Other plants like Mango, Groundnut, and Beans have a branching vein pattern known as reticulate venation, which is found in dicot plants.

Here's why the other answers are incorrect:

• A. Mango: Mango leaves have reticulate venation, typical of dicots.
• B. Groundnut: Groundnut leaves also have reticulate venation, not parallel.
• D. Beans: Beans, like Mango and Groundnut, have reticulate venation, not parallel venation.

Explanation:

The correct answer is: D. Magnification

Magnification is the ratio of the drawn size (or image size) to the actual size of an object. It is used to show how much larger an object appears compared to its real size. This term is commonly used in microscopes and other instruments to measure how much an object is enlarged.

Here's why the other answers are incorrect:

• A. Mortality rate: This refers to the rate of death in a population, not to the size of an object.
• B. Population: This refers to the number of individuals in a given area, not the size ratio of an object.
• C. Fecundity rate: This is the rate of reproduction in a population, unrelated to the size of an object.

Explanation:

The correct answer is: C. Bacteria

Bacteria can be shaped like spheres or balls, which are called "cocci." Bacteria can have different shapes, but cocci is one of the most common. Fungi, viruses, and protozoa do not have this ball shape.

Why the other answers are wrong:

• A. Fungi: Fungi are usually not round; they can have different shapes but not cocci.
• B. Viruses: Viruses are much smaller than bacteria and do not have a cocci shape.
• D. Protozoa: Protozoa are single-celled organisms, but they do not have a round shape like cocci.

Explanation:

The correct answer is: A. Bacterium

The organism that causes cholera is a bacterium called Vibrio cholerae. It attacks the stomach and intestines, causing severe diarrhea. This leads to dehydration, which can be deadly without treatment.

Why the other answers are incorrect:

• B. Virus: Cholera is not caused by a virus. Viruses are different types of germs that cause illnesses like the flu, not cholera.
• C. Protozoon: Protozoa are single-celled organisms, but they do not cause cholera. They are responsible for other diseases, like malaria.
• D. Fungus: Fungi are organisms like molds and mushrooms. They do not cause cholera. Fungal infections affect the skin or lungs, not the intestines like cholera.

Explanation:

The correct answer is: D. I – II – III – IV

When we look at the complexity of these organisms, Hydra (I) is the simplest because it is a small, simple animal. Then, the Owl (II) comes next, followed by the Snake (III). Finally, the Snail (IV) is the most complex because it has more advanced features, like a brain and a more developed nervous system.

Why the other answers are wrong:

• A. IV – III – II – I: This order starts with Snail (IV), which is the most complex organism, but it should start with the simplest (Hydra, I).
• B. II – III – I – IV: This order places the Owl (II) before the Snake (III) and Hydra (I) at the end, which is not correct because Hydra is the simplest, not the most complex.
• C. I – IV – III – II: This order places the Snail (IV) before the Snake (III) and Owl (II), but Snail is more complex than both, so this order is incorrect.

Explanation:

The correct answer is: D. Mollusca

The organism labelled as IV, which is a snail, belongs to the Phylum Mollusca. Mollusks are soft-bodied animals, and many of them have shells. Snails, clams, and octopuses are examples of mollusks.

Why the other answers are wrong:

• A. Arthropoda: This phylum includes animals like insects, spiders, and crustaceans. These animals have hard exoskeletons, which is different from snails.
• B. Platyhelminthes: These are flatworms, which have soft, flat bodies. They are very different from snails.
• C. Coelenterata: This phylum includes simple animals like jellyfish and corals. They have soft, often jelly-like bodies, unlike the hard shell of a snail.

Explanation:

The correct answer is: A. IV

In the chloroplast (IV), sunlight, water, and carbon dioxide come together during the process called photosynthesis. This process produces sugar (glucose) and oxygen. The chloroplast is the part of the cell that makes food for the plant.

Why the other answers are incorrect:

• B. III – Cell Wall: The cell wall provides structure to the cell, but it does not play a role in making sugar.
• C. II – Nucleus: The nucleus controls the cell's activities but is not involved in the process of photosynthesis.
• D. I – Vacuole: The vacuole stores water and other materials, but it is not where photosynthesis happens.

Explanation:

The correct answer is: A. IV

The oxygen gas produced during photosynthesis in the chloroplast (IV) moves out of the plant cell and enters the air through small openings called stomata (found in the leaves). These stomata allow gases like oxygen and carbon dioxide to move in and out of the plant.

Why the other answers are incorrect:

• B. III – Cell Wall: The cell wall provides structure to the plant but does not allow gas exchange. Oxygen passes through the stomata, not the cell wall.
• C. II – Nucleus: The nucleus controls the cell's functions but is not involved in the movement of gases like oxygen.
• D. I – Vacuole: The vacuole stores water and other materials but does not play a role in the movement of gases.

Explanation:

The correct answer is: D. Movement of water from root hairs into cortical cell.

Osmosis is when water moves from an area with fewer water molecules (lower concentration) to an area with more water molecules (higher concentration) through a semipermeable membrane. In plants, water moves from the root hairs (where there is a higher concentration of water) into the cortical cells (where there is a lower concentration of water). This is a clear example of osmosis.

Why the other answers are incorrect:

• A. Reabsorption of food nutrients from the kidney into blood capillaries: This process involves active transport, not osmosis. Active transport moves substances against their concentration gradient, which is different from osmosis.
• B. Translocation of starch from leaves to all parts of a plant: This is a process called translocation, where starch is moved through the plant, but it does not involve osmosis. It involves the phloem.
• C. Movement of digested food from ileum into blood capillaries: This process is called absorption and occurs by diffusion, not osmosis.

Explanation:

The correct answer is: D. Plants grow indefinitely.

Unlike animals, which stop growing once they reach a certain size, most plants continue to grow throughout their entire life. This type of growth in plants is called indefinite growth. Plants can keep adding new cells in different parts like the tips of roots and stems, allowing them to grow continuously.

Why the other answers are incorrect:

• A. Plants are intercalary: Intercalary growth refers to growth at specific regions in plants, such as between nodes. This is not the main reason why plant growth is different from animals.
• B. Plants grow from within: While plants grow from within, this does not explain why their growth is different from animals. Both plants and animals have internal growth processes.
• C. Animals are apical: Apical growth happens at the tips in both animals and plants, but it’s not the main difference. The key difference is that plants keep growing indefinitely, while animals stop growing once they reach a certain size.

Explanation:

The correct answer is: C. Axial skeleton.

The skull is part of the axial skeleton. The axial skeleton includes the bones that form the central axis of the body, like the skull, spine (vertebral column), and rib cage. These bones protect vital organs such as the brain, heart, and lungs.

Why the other answers are incorrect:

• A. Cervical vertebrae: The cervical vertebrae are part of the spine, not the skull. They are the first seven vertebrae in the neck region.
• B. Appendicular skeleton: The appendicular skeleton includes the limbs (arms and legs) and the girdles (shoulder and pelvic) that connect them to the body, but not the skull.
• D. Axis vertebrae: The axis is a specific vertebra in the neck (second cervical vertebra) that helps the head rotate. It is not related to the skull itself.

Explanation:

The correct answer is: B. Eye, cerebellum, and ear.

The skull protects important parts of the body, including the brain (which contains the cerebellum), eyes, and ears. If the skull is injured, these parts are most likely to be affected because they are inside the skull and protected by it.

Why the other answers are incorrect:

• A. Lumbar, eye, and teeth: The lumbar (lower back) and teeth are not protected by the skull. The teeth are located in the mouth, and the lumbar is part of the spine.
• C. Ear, brain, and hinge joint: While the ear and brain are inside the skull, a hinge joint (like the knee or elbow) is not related to the skull. It is a joint in the limbs.
• D. Clavicle, tongue, and pelvis: The clavicle (collarbone), tongue, and pelvis are not part of the skull. The clavicle and pelvis are bones of the body, and the tongue is in the mouth, which is not protected by the skull.

Explanation:

The correct answer is: D. Right auricle and right ventricle.

The tricuspid valve is found between the right auricle (upper chamber) and the right ventricle (lower chamber) of the heart. It helps control blood flow from the right auricle to the right ventricle.

Why the other answers are incorrect:

• A. Left auricle and left ventricle: This refers to the bicuspid (mitral) valve, not the tricuspid valve. The bicuspid valve is between the left auricle and left ventricle.
• B. Aorta and left ventricle: This refers to the aortic valve, not the tricuspid valve. The aortic valve controls blood flow from the left ventricle to the aorta.
• C. Right auricle and the superior vena cava: This is incorrect because the superior vena cava carries blood into the right auricle, but there is no valve between them.

Explanation:

The correct answer is: A. Larynx.

The larynx, also known as the voice box, contains the vocal cords. These vocal cords vibrate when air passes through them, producing sound.

Why the other answers are incorrect:

• B. Bronchus: The bronchus is part of the airways that carry air to the lungs, but it does not produce sound.
• C. Bronchiole: Bronchioles are small airways in the lungs. They help air reach the alveoli but do not produce sound.
• D. Trachea: The trachea (windpipe) carries air to and from the lungs, but sound is not produced here.

Explanation:

The correct answer is: A. Lung.

Bronchioles are small air passages that are located in the lungs. They carry air to the alveoli, where oxygen is exchanged with carbon dioxide in the blood.

Why the other options are incorrect:

• B. Heart: The heart pumps blood, but it does not contain bronchioles.
• C. Sternum: The sternum is the breastbone and is not involved in air passage.
• D. Kidney: The kidneys filter blood but are not related to air passage or bronchioles.

Explanation:

The correct answer is: C

Adrenalin is produced by the adrenal glands, not the kidneys. The adrenal glands are located on top of the kidneys, but they are different organs.

Why the other options are correct:

• A. Oxytocin and hypothalamus: Oxytocin is produced by the hypothalamus and stored in the pituitary gland.
• B. Oestrogen and ovary: Oestrogen is produced by the ovaries in females.
• D. Insulin and pancreas: Insulin is produced by the pancreas to regulate blood sugar levels.

Explanation:

The correct answer is: D

Astigmatism happens when the front part of your eye (cornea) or the lens inside your eye is shaped unevenly. This makes your vision blurry or stretched out. It's like looking through a wobbly glass.

Why the other options are wrong:

• A. Myopia (nearsightedness): You can see nearby objects clearly, but things far away look blurry. This happens because your eye is too long or the lens is too curved.
• B. Hypermetropia (farsightedness): You can see far objects clearly, but nearby things look blurry. This happens when your eye is too short or the lens isn't strong enough.
• C. Presbyopia: This happens when you get older, and your eye's lens can't change shape easily, so it becomes harder to see close objects.

Explanation:

The correct answer is: D

The androecium is the male part of the flower. It is made up of stamens, which are the parts that produce pollen. Each stamen has two parts: the filament (a thin stalk) and the anther (where the pollen is made).

Why the other options are wrong:

• A. Ovules are the female parts inside the flower where seeds form, not part of the androecium.
• B. Sperms are male sex cells, but they are produced by the pollen in the stamens, not part of the androecium itself.
• C. Filaments are part of the stamen, but they are not the whole androecium.

Explanation:

The correct answer is:

C. Arrangement of ovules in the ovary of a flower

Topic: Plant Reproduction

Placentation is the way ovules (the parts that become seeds) are arranged inside the ovary of a flower. This arrangement helps the seeds grow properly.

• A. Part of the ovary where the ovules originate and remain till maturity: This is about where ovules start and grow, but it doesn’t explain how they are arranged, which is what placentation is about.


• B. Ovules borne on a central column of tissues in an ovary: This describes one type of placentation but doesn't explain the general meaning of placentation.


• D. Formation of a single camel joined at the two edges of an ovule: This is not related to placentation and doesn't make sense in this context.

Explanation:

The correct answer is:

C. Carbon (IV) oxide is evolved

Topic: Photosynthesis

During photosynthesis, plants use sunlight to make food (glucose) from water and carbon dioxide. Here's what happens:

• A. Oxygen is evolved: Oxygen is produced during photosynthesis as a result of splitting water. This is correct.


• B. Water is split: Water is split during photosynthesis to release oxygen. This is also correct.


• D. Energy from sunlight is absorbed: Plants absorb sunlight to start the process of photosynthesis. This is also correct.

Explanation:

The correct answer is:

D. Nitrogen

Topic: Plant Nutrition

Nitrogen is very important for plants because it helps them grow and makes chlorophyll, the green pigment in leaves.

• A. Magnesium: Magnesium is also important for plants, but it causes yellowing in older leaves. It doesn’t typically cause stunted growth and yellow leaves on all the plant's leaves like nitrogen does.


• B. Iron: Iron deficiency causes yellowing of young leaves, but it doesn't usually cause stunted growth like nitrogen does.


• C. Sulphur: Sulphur deficiency causes yellowing of young leaves, but it doesn't usually cause the plant to stop growing or become stunted as nitrogen deficiency does.

Explanation:

The correct answer is:

C. Epiglottis

Topic: Human Digestive and Respiratory Systems

The epiglottis is a small flap of tissue at the top of your windpipe (the tube you breathe through). It closes when you swallow food or drink to make sure it goes down the right tube (the food pipe).

• A. Liver: The liver helps with digestion, but it doesn’t stop choking.


• B. Oesophagus: The oesophagus is the tube that carries food to your stomach, but it doesn’t control choking.


• D. Stomach: The stomach is where food goes to get digested, but it doesn’t cause choking.

Explanation:

The correct answer is:

B. Fat

Topic: Food and Nutrition

Fat gives the most energy compared to other food types.

One gram of fat gives about 9 kilocalories of energy, while proteins and carbohydrates give about 4 kilocalories per gram. This means fat provides more than twice the energy of proteins or carbohydrates.

• A. Protein: Protein helps with growth and repair, but it doesn’t provide as much energy as fat.


• C. Amino acid: Amino acids are building blocks of protein. They help with body repair but don’t give much energy by themselves.


• D. Glucose: Glucose gives energy, but it’s less than fat. It's the sugar the body uses quickly for energy.

Explanation:

The correct answer is:

A. Saprophytes

Topic: Modes of Nutrition

Saprophytes are organisms that feed on dead plants or animals. They break down decaying matter to get their food.

• B. Autotrophs: Autotrophs make their own food, like plants that use sunlight. They don’t feed on dead things.


• C. Heterotrophs: Heterotrophs need to eat other living things for food, but not just dead things like saprophytes.


• D. Parasites: Parasites live off other living organisms, but they don’t feed on dead things.

Explanation:

The correct answer is:

B. Holozoic

Topic: Nutrition in Organisms

Holozoic nutrition is when organisms eat solid food, break it down inside their body, and absorb the nutrients. This is how most animals, including humans, get their food.

• A. Symbiotic: Symbiotic nutrition happens when two different organisms live together and help each other. They don’t eat solid food like in holozoic nutrition.


• C. Saprophytic: Saprophytic nutrition is when organisms feed on dead plants or animals. They break down decaying matter, not solid food.


• D. Parasitic: Parasitic nutrition is when one organism lives off another, harming it. They don’t take in solid food the way holozoic organisms do.

Explanation:

The correct answer is:

D. Chewing

Topic: Adaptation in Insects

Grasshoppers have strong mouthparts that help them chew food. They use their jaws to bite and grind leaves and stems. This helps them break down tough plant material.

• A. Absorption: Absorption means taking in nutrients, but grasshoppers don’t absorb food directly. They chew it first.


• B. Grinding: Grinding is part of chewing, but the main job of their mouthparts is to chew food into smaller pieces.


• C. Sucking: Sucking mouthparts are found in insects like mosquitoes, but grasshoppers chew their food, not suck it.

Explanation:

The correct answer is:

D. Community

Topic: Ecological Interactions

A community is a group of different species living together in the same place and interacting with each other.

• A. Biosphere: The biosphere is the entire Earth, including all living and non-living things. It’s much bigger than a community.


• B. Population: A population is a group of organisms of the same species living in an area, not different species.


• C. Niche: A niche is the role or function an organism has in its environment, not the group of species it lives with.

Explanation:

The correct answer is:

C. Lack of adequate water

Topic: Adaptations of Plants

Xerophytes are plants that live in dry areas where water is hard to find. Their main problem is not having enough water.

• A. Poor formation of roots: Xerophytes actually have well-developed root systems to help them find and store water.


• B. Competition for sunlight: Xerophytes don’t usually face problems with sunlight because they often grow in open areas with plenty of sun.


• D. Conservation of excess water: Xerophytes are focused on conserving the little water they have, not on having too much.

Explanation:

The correct answer is:

D. Gills

Topic: Adaptations of Aquatic Animals

Fishes need to get oxygen from the water to survive, and they do this with their gills. Gills allow fishes to take oxygen from water, which they need for breathing (respiration).

Without gills, fishes wouldn't be able to breathe in water, so this is their most important feature for survival.

• A. Paired fins: Fins help fish move in the water, but they don’t help them breathe.


• B. Scales: Scales protect the fish's body but aren't needed for breathing.


• C. Streamlined body: A streamlined body helps fish swim faster, but it doesn’t help with breathing.

Explanation:

The correct answer is:

D. Microscope

Topic: Abiotic Factors and Their Measurement

Abiotic factors are the non-living parts of a habitat that affect living organisms, such as temperature, humidity, wind speed, and soil type. Common instruments used to measure these factors are:

• A. Wind vane: This measures the direction of the wind.


• B. Thermometer: This measures temperature.


• C. Hygrometer: This measures the humidity of the air.

However, a microscope is used to observe tiny organisms or cells and does not measure abiotic factors. This is why it is the correct answer.

Explanation:

The correct answer is:

B. Silt and clay

Topic: Soil Properties

Capillarity is the ability of soil to draw water upward through tiny spaces. Soils with smaller particles, like silt and clay, have high capillarity because their small particles provide more surface area for water to stick to. This allows water to move upward, which is important for plants to get water from the soil.

Here’s why the other options are incorrect:

• A. Sand and loam: Sand has large particles, so it drains water quickly and has low capillarity. Loam has better water retention but doesn't have the highest capillarity compared to silt and clay.


• C. Sand and silt: While silt has high capillarity, sand has large particles and low capillarity, which makes this combination not the best fit.


• D. Clay and sand: Clay has high capillarity, but sand has low capillarity, so this combination doesn’t fit either.

Explanation:

The correct answer is:

D. Heterotrophic

Topic: Types of Nutrition in Plants

The pitcher plant is a carnivorous plant that gets some of its nutrients by capturing and digesting insects. This form of nutrition is called heterotrophic nutrition. It means the plant gets its food by consuming other living things, like insects, because it can't make all the nutrients it needs from the soil.

Here’s why the other options are incorrect:

• A. Chemosynthetic: This type of nutrition involves making food from chemicals, not from consuming other organisms. It doesn't apply to pitcher plants.


• B. Autotrophic: Autotrophic plants make their own food through photosynthesis, like most plants. Pitcher plants can't do this for all nutrients, so they depend on insects for some of their nutrition.


• C. Saprophytic: Saprophytic nutrition involves feeding on dead organic matter. Pitcher plants eat live insects, so this is not the correct type of nutrition for them.

Explanation:

The correct answer is:

B. Maize

Topic: Producers in Food Chains

In a food chain, producers are organisms that can make their own food using sunlight, water, and carbon dioxide through photosynthesis. Maize (B) is a plant that uses photosynthesis to produce food, so it is the producer in this food chain.

Here's why the other options are not correct:

• A. Man: Humans are consumers, not producers. We rely on plants and animals for food.


• C. Goat: A goat is a herbivore and consumer. It eats plants to get energy.


• D. Bacterium: While some bacteria can be producers (like those involved in chemosynthesis), most bacteria are consumers or decomposers, not producers in a typical food chain.

Explanation:

The correct answer is:

D. Availability of moisture

Topic: Decomposition in Ecosystems

The rate of decomposition is faster in tropical rainforests because there is a lot of moisture (water) in the air and soil. Moisture helps tiny organisms, like bacteria and fungi, break down dead plants and animals quickly. These organisms need water to live and work, and the rainforest has plenty of it.

Here’s why the other answers are not correct:

• A. More plants: While there are a lot of plants in the rainforest, it is the moisture that really helps decomposition happen quickly, not just the number of plants.


• B. Constant daylight: The rainforest does get a lot of daylight, but moisture is the main reason why decomposition is fast, not the light.


• C. Consistent cool temperature: Tropical rainforests are warm, not cool. Warm temperatures help decomposition, while cool temperatures slow it down.

Explanation:

The correct answer is:

C. Predation

Topic: Ecological Relationships

Predation is when one animal hunts and eats another. Here, the small bird (III) is eaten by the eagle (IV). The eagle is the predator, and the small bird is the prey.

Here’s why the other answers are incorrect:

• A. Parasitism: This involves one organism living off another and causing harm, but in this case, the eagle is killing and eating the bird, not just harming it.


• B. Mutualism: Mutualism is when both organisms benefit, but here the eagle benefits while the bird is harmed.


• D. Saprophytism: This is when organisms feed on dead or decaying matter, which doesn’t apply to the eagle eating the bird.

Explanation:

The correct answer is:

B. I

Topic: Producers and Consumers in a Food Chain

The producer is the organism that can make its own food using sunlight. This process is called photosynthesis. In this case, organism I (leaf) is the producer because it uses sunlight to create food. The leaf is the starting point of the food chain.

Here’s why the other answers are incorrect:

• A. I: While it’s true that the leaf contains less energy compared to higher levels in the food chain, it is still the producer because it makes food using sunlight.


• C. IV: The eagle (IV) is not a producer. It is a consumer that eats other animals.


• D. IV: The eagle receives sunlight, but it does not use it to make food. It relies on other organisms for energy, so it is not a producer.

Explanation:

The correct answer is:

B. Deforestation

Topic: Conservation of Natural Resources

Deforestation is when trees and plants are cut down or destroyed, often without planting new ones. This harms the environment by causing soil erosion, loss of animals, and more carbon in the air.

Here’s why the other answers are not correct:

• A. Establishment of game reserves: Game reserves protect animals and their habitats, which helps preserve natural resources.


• C. Afforestation: Afforestation means planting new trees, which is good for the environment and helps conserve resources.


• D. Contour ploughing: This is a farming method that helps prevent soil erosion and protects the land.

Explanation:

The correct answer is: C

Topic: Conservation of Natural Resources

Making tables with plastic is a better choice for the environment because it does not harm wildlife or forests. This option avoids the use of animal products like elephant tusks and crocodile skin, and it reduces the need for cutting down trees for firewood.

Here's why the other options are not good choices:

• A. IV. Using firewood for cooking: This requires cutting down trees and contributes to deforestation, which harms forests.
• B. III. Using elephant tusk for decoration: This is harmful to elephant populations, as elephants are endangered, and using tusks promotes illegal poaching.
• D. I. Making shoes from crocodile skin: Crocodiles are also endangered, and using their skin contributes to the decline of their population.

Explanation:

The correct answer is: A

Topic: Conservation Strategies

The government plays an important role in protecting the environment. By enacting and enforcing laws, the government can ensure that natural resources, wildlife, and forests are protected from harmful practices. Laws help control illegal activities like poaching and deforestation, ensuring that the resources are used responsibly.

Here's why the other options are not good choices:

• B. Promote felling of trees without planting new ones: This leads to deforestation, which harms the environment and reduces the number of trees that help clean the air and provide habitats for animals.
• C. Encourage over-utilization of forest resources: Overusing resources like trees and water can lead to depletion, causing long-term damage to ecosystems.
• D. Encourage indiscriminate killing of wildlife: This harms animal populations and threatens biodiversity, leading to the extinction of endangered species.

Explanation:

The correct answer is: C

Topic: Genetics – Variation

Discontinuous variation refers to characteristics that fall into separate, distinct categories with no in-between forms. The colour of flowers is a good example, as it can only be one colour (e.g., red, white, or purple) without mixing in between.

Here’s why the other options are not correct:

• A. Leaf size: This shows continuous variation because leaf size can vary gradually (e.g., from small to large) rather than being one of a few distinct sizes.
• B. Height of plant: Plant height also shows continuous variation, as plants can grow to any height within a range, not in fixed categories.
• D. Fruit size: Fruit size, like leaf size and plant height, shows continuous variation, with many possible sizes within a given range.

Explanation:

The correct answer is: B

Topic: Blood Groups and Reproductive Health

If a Rhesus negative (Rh-) woman is carrying a Rhesus positive (Rh+) baby, her body might treat the baby’s blood as a foreign substance. This happens when the mother’s immune system makes antibodies against the baby’s blood cells. This is more likely after the first pregnancy.

In later pregnancies, these antibodies can cross the placenta and cause the baby’s blood cells to clump together. This is called hemolytic disease, which can lead to stillbirth or miscarriage if not treated.

Here’s why the other options are incorrect:

• A. Poor circulatory system: This is not the cause. The problem is due to the immune system reacting to the baby’s blood.
• C. Susceptibility to diseases during pregnancy: While infections can affect pregnancy, this issue is caused by the immune system’s reaction to the baby’s blood cells, not by disease.
• D. Deprivation of nourishment: This does not cause stillbirth in this case. The problem is the clumping of blood cells, not a lack of nutrients.

Explanation:

The correct answer is: B

Topic: Genetics – Mutation

A mutation is a sudden change in the DNA (genetic material) of an organism. This change can happen by chance or because of things like radiation or chemicals.

Why the other options are not correct:

• A. Epistasis: This is when one gene affects another gene, but it doesn’t cause sudden changes in DNA.
• C. Linkage: Linkage means genes are passed together, not a sudden change in the DNA.
• D. Variation: Variation is just the difference between organisms, but it doesn’t mean a sudden change in DNA like a mutation.

Explanation:

The correct answer is: C

Topic: Genetics – DNA and Inheritance

A DNA test is the most accurate way to settle paternity disputes. It looks at the child’s and the father's DNA to see if they share matching genes.

Why the other options are incorrect:

• A. Tongue rolling: This is just a genetic trait, and it can’t be used to determine paternity.
• B. Blood group: Blood group can only rule out some possibilities but can’t be used to prove paternity with certainty.
• D. Finger printing: Fingerprints are unique, but they aren’t directly related to paternity testing like DNA is.

Explanation:

The correct answer is: C

Topic: Genetics – Genetic Diagrams

A Punnett square is a table used to show all the possible ways genes from two parents can combine to form the offspring’s genotype. It is a simple grid where you write down the alleles from each parent to see the different combinations.

Why the other options are incorrect:

• A. Inheritance diagram: This is a general term for diagrams showing how traits are passed down, but it doesn't specifically refer to a table like the Punnett square.
• B. Genetic cross: This is the process of breeding two organisms to see how traits are passed down, but it is not a table. A Punnett square is used to show the result of a genetic cross.
• D. Genetic square: This is not a commonly used term for any genetic diagram.

Explanation:

The correct answer is: A

Topic: Genetics – Monohybrid Cross

In this cross, one parent has the genotype EE, and the other has Ee. The possible gametes (or sex cells) are:

• EE parent can only give E
• Ee parent can give either E or e

The possible offspring genotypes are:

• EE (from E + E)
• Ee (from E + e)

The genotype ee is not possible because the EE parent cannot give an "e" allele. Also, Ee and eE are the same genotype because the order of the alleles doesn’t matter.

Why the other options are correct:

• B. Ee: This is possible (E from EE parent, e from Ee parent).
• C. eE: This is the same as Ee, so it’s possible (E from EE parent, e from Ee parent).
• D. EE: This is possible (E from both parents).

Explanation:

The correct answer is: C

Topic: Genetics – Monohybrid Cross

In this cross, one parent has the genotype BB (homozygous dominant), and the other has Bb (heterozygous). The possible gametes are:

• BB parent can only give B.
• Bb parent can give either B or b.

The possible offspring genotypes are:

• BB (from B + B)
• Bb (from B + b)

This means 50% of the offspring will be BB, and 50% will be Bb. Since both BB and Bb show the dominant phenotype, the genotypic ratio (based on genotype) is 4:0 for dominant expression, because there’s no bb (recessive) genotype possible.

Why the other options are incorrect:

• A. 1:1: This ratio is actually the correct one if we focus on the number of BB and Bb genotypes.
• B. 1:3: This ratio would occur in a cross between heterozygous parents (Bb x Bb), not BB x Bb.
• D. 1:2:1: This ratio would be correct in a cross between two heterozygous parents (Bb x Bb).

Explanation:

The correct answer is: B

Topic: Genetics – Sex Determination

The probability of having a male child is 1/2, or 50%. This is because:

• Females have two X chromosomes (XX).
• Males have one X and one Y chromosome (XY).

When a sperm fertilizes an egg, the sperm can carry either an X or a Y chromosome. The egg will always have an X chromosome. If the sperm carries a Y chromosome, the child will be male (XY); if it carries an X chromosome, the child will be female (XX).

Since there’s a 50% chance of the sperm carrying either X or Y, the probability of a male child is 1/2.

Why the other options are incorrect:

• A. 1/4: This would apply if considering the probability of multiple events with more than two possible outcomes.
• C. 3/4: This would be the probability of having a female child if the sperm always carried an X chromosome.
• D. 1: This would mean that every pregnancy results in a male child, which is not the case.

Explanation:

The correct answer is: D

Topic: Evolution – Vestigial Organs

The tail bone, or coccyx, is a vestigial structure in humans. It is a leftover part from when our ancestors had tails. Today, it doesn't do much, but it helps support some muscles around the pelvis.

Here’s why the other options are not correct:

• A. Gall bladder: It helps digest food by storing bile.
• B. Earlobe: It doesn't serve much of a purpose now, but it’s not considered vestigial.
• C. Villus: These are tiny parts inside the intestines that help absorb food.

Explanation:

The correct answer is: B

Topic: Ecology – Insect Behavior

Termites are known for activities like searching for food (especially wood), communicating with each other using chemicals and vibrations, and flying during their mating season (nuptial flight).

However, termites do not pollinate plants. Pollination is done mainly by bees, butterflies, and other insects that carry pollen from one flower to another.

Here’s why the other options are correct for termites:

• A. Searching for food: Termites are known for eating wood and searching for it.
• C. Communication: They use chemicals (pheromones) and vibrations to communicate.
• D. Nuptial flight: This is when termites fly to mate during specific times of the year.