JAMB Biology 2023 Past Questions and Answers

Here are the complete JAMB Biology 2023 Past Questions and Answers. The answers are well-detailed and explained.

1. Which of the following is an example of a microorganism in action as a disease vector?

A. Fungi decomposing dead plant material
B. Mosquito transmitting malaria
C. Bacteria causing food poisoning
D. Algae producing oxygen through photosynthesis

The correct answer is (B) Mosquito transmitting malaria.

Explanation:

A disease vector is an organism that transmits a pathogen (like a virus, bacterium, or parasite) from one host to another. In this case, the mosquito acts as a vector for the Plasmodium parasite, which causes malaria. When a mosquito bites an infected person, it picks up the parasite and can then transmit it to another person through a subsequent bite.

Why not the others?

(A) Fungi decomposing dead plant material: This is an example of saprophytic nutrition, where fungi break down organic matter. It does not involve disease transmission.
(C) Bacteria causing food poisoning: While bacteria like Salmonella or E. coli can cause food poisoning, they are not acting as vectors. They directly infect the host through contaminated food or water.
(D) Algae producing oxygen through photosynthesis: This is a beneficial process where algae contribute to oxygen production in the environment. It has no relation to disease transmission.

Thus, the mosquito transmitting malaria is the best example of a microorganism in action as a disease vector.

A. Ability to respond to stimuli
B. Ability to synthesize proteins
C. Ability to generate energy
D. Ability to replicate DNA

The correct answer is (A) Ability to respond to stimuli.

Explanation:

Irritability (also called responsiveness or sensitivity) is a fundamental characteristic of living cells. It refers to the ability of cells to detect and respond to changes in their environment (stimuli). These stimuli can be physical (like light, temperature, or pressure) or chemical (like hormones or nutrients). For example:

Nerve cells (neurons) respond to electrical or chemical signals.
Plant cells respond to light by growing toward it (phototropism).

Why not the others?

(B) Ability to synthesize proteins: This is a function related to gene expression and cellular metabolism, not irritability.
(C) Ability to generate energy: This refers to cellular respiration or photosynthesis, which are metabolic processes, not responsiveness.
(D) Ability to replicate DNA: This is related to cell division and reproduction, not the ability to respond to stimuli.

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

3. The membrane around the vacuole is known as

A. Elaioplast
B. Amyloplast
C. Tonoplast
D. Cytoplast

The correct answer is (C) Tonoplast.

Explanation:

The tonoplast is the membrane that surrounds the vacuole in plant cells. It plays a crucial role in maintaining the internal environment of the vacuole, regulating the movement of ions, nutrients, and waste products in and out of the vacuole. The vacuole itself is a large, fluid-filled organelle that stores water, nutrients, and waste materials, and helps maintain turgor pressure in plant cells.

Why not the others?

(A) Elaioplast: This is a type of plastid involved in storing lipids (fats) and is not related to the vacuole.
(B) Amyloplast: This is another type of plastid that stores starch and is found in plant cells, but it is not associated with the vacuole.
(D) Cytoplast: This term is not commonly used in cell biology. It might be confused with “cytoplasm,” which is the gel-like substance filling the cell, but it is not a membrane.

Thus, the membrane around the vacuole is called the tonoplast.

4. Which of the following is evidence of evolution?

A. All of the above.
B. Similarities in embryonic development
C. Fossils of extinct organisms
D. Homologous structures in different species

The correct answer is (A) All of the above.

Explanation:

All the options listed—similarities in embryonic development, fossils of extinct organisms, and homologous structures in different species—are key pieces of evidence supporting the theory of evolution. Let’s break them down:

(B) Similarities in embryonic development:
- Embryos of different species often show striking similarities during early stages of development. For example, fish, birds, and mammals all have gill slits and tails at some point in their embryonic stages. This suggests a common ancestry and supports the idea of evolution.
(C) Fossils of extinct organisms:
- Fossils provide a record of past life forms, showing how species have changed over time. Transitional fossils (like Archaeopteryx, which shows traits of both dinosaurs and birds) are particularly strong evidence for evolution.
(D) Homologous structures in different species:
- Homologous structures are body parts in different species that have a similar structure but may serve different functions. For example, the forelimbs of humans, bats, and whales all have the same basic bone structure, indicating they evolved from a common ancestor.

Why is (A) correct?

Since all the options (B, C, and D) are valid and widely accepted evidence of evolution, the most comprehensive answer is (A) All of the above. Each piece of evidence contributes to our understanding of how species have evolved over time.

A. Migration to warmer climates
B. Production of venom for defense
C. Formation of complex caste systems
D. Hibernation during winter months

The correct answer is (C) Formation of complex caste systems.

Explanation:

Social insects, such as ants, bees, termites, and wasps, exhibit highly organized social structures with complex caste systems. These systems divide labor among different groups (castes) within the colony, such as queens, workers, soldiers, and drones. This adaptation enhances the survival and efficiency of the colony by ensuring that specific tasks (e.g., reproduction, foraging, defense, and care of young) are performed by specialized individuals.

Why not the others?

(A) Migration to warmer climates: While some animals migrate to survive seasonal changes, this is not a common adaptation in social insects. They typically rely on their nests or hives for survival during harsh conditions.
(B) Production of venom for defense: While some social insects (like bees and wasps) produce venom, this is more of an individual defense mechanism rather than a social adaptation for colony survival.
(D) Hibernation during winter months: Hibernation is a survival strategy used by some animals, but social insects like bees and ants rely on their colonies to maintain warmth and food stores during winter, rather than hibernating.

6. Which of the following is NOT a part of the alimentary canal?

A. Oesophagus
B. Large intestine
C. Liver
D. Small intestine

The correct answer is (C) Liver.

Explanation:

The alimentary canal (also called the digestive tract) is a continuous tube that runs from the mouth to the anus and is responsible for the digestion and absorption of food. It includes the following structures:

Mouth
Oesophagus (A)
Stomach
Small intestine (D)
Large intestine (B)
Rectum
Anus

The liver (C), however, is not part of the alimentary canal. Instead, it is an accessory organ that aids in digestion by producing bile, which helps break down fats. Bile is stored in the gallbladder and released into the small intestine, but the liver itself is not part of the digestive tract.

Why not the others?

(A) Oesophagus, (B) Large intestine, and (D) Small intestine are all direct parts of the alimentary canal.

Thus, the liver is not part of the alimentary canal.

7. Which of the following is an evolutionary trend commonly observed in organisms?

A. Decreased complexity over time
B. Increased dependence on external resources
C. Increased genetic diversity within populations
D. Decreased adaptation to the environment

The correct answer is (C) Increased genetic diversity within populations.

Explanation:

An evolutionary trend refers to a general pattern of change observed in organisms over time. One of the most commonly observed trends is increased genetic diversity within populations. Genetic diversity is crucial for the survival and adaptability of a species, as it provides the raw material for natural selection to act upon. Greater genetic diversity allows populations to better cope with environmental changes, diseases, and other challenges.

Why not the others?

(A) Decreased complexity over time: While some organisms may evolve simpler forms in specific environments (e.g., parasites), the overall trend in evolution is toward increased complexity, not decreased complexity.
(B) Increased dependence on external resources: This is not a general evolutionary trend. Organisms evolve to become more efficient in utilizing resources, not necessarily more dependent on them.
(D) Decreased adaptation to the environment: Evolution is driven by natural selection, which favors traits that improve an organism’s adaptation to its environment. Therefore, decreased adaptation is not a trend but rather the opposite of what evolution typically achieves.

Thus, increased genetic diversity within populations is a well-documented evolutionary trend.

8. Which of the following is a characteristic feature of Kingdom Plantae?

A. Presence of chloroplasts
B. Ability to perform photosynthesis
C. Lack of cell walls
D. Heterotrophic mode of nutrition

The correct answer is (A) Presence of chloroplasts.

Explanation:

Kingdom Plantae is characterized by several key features, one of which is the presence of chloroplasts. Chloroplasts are organelles that contain chlorophyll, the pigment responsible for capturing light energy and enabling photosynthesis. This is a defining trait of plants, as it allows them to produce their own food (autotrophic nutrition) using sunlight, water, and carbon dioxide.

Why not the others?

(B) Ability to perform photosynthesis: While this is true for most plants, it is a result of having chloroplasts. The presence of chloroplasts is the more fundamental characteristic.
(C) Lack of cell walls: This is incorrect. Plants have rigid cell walls made of cellulose, which provide structural support and protection.
(D) Heterotrophic mode of nutrition: This is incorrect. Plants are autotrophic, meaning they produce their own food through photosynthesis. Heterotrophic organisms, like animals and fungi, rely on consuming other organisms for nutrition.

Thus, the presence of chloroplasts is a characteristic feature of Kingdom Plantae.

9. A biome characterized by hot summer, warm winter and treeless vegetation is

A. Steppe grasslands
B. Temperate deserts
C. Savannah grassland
D. Tropical deserts

The correct answer is (A) Steppe grasslands.

Explanation:

A steppe grassland is a biome characterized by:

Hot summers and warm winters.
Treeless vegetation, dominated by grasses and shrubs.
Moderate rainfall, which is insufficient to support forests but enough to sustain grasslands.

Steppe grasslands are found in regions like central Asia, parts of North America (e.g., the Great Plains), and eastern Europe.

Why not the others?

(B) Temperate deserts: These are characterized by hot summers but cold winters, and they have very sparse vegetation due to low rainfall.
(C) Savannah grasslands: These are tropical or subtropical biomes with distinct wet and dry seasons and scattered trees or shrubs. They are not treeless.
(D) Tropical deserts: These are characterized by extremely hot temperatures year-round and very little rainfall, resulting in sparse vegetation. They are not typically associated with warm winters.

Thus, the biome described in the question is the steppe grassland.

10. Which of the following is an example of physiological variation in organisms?

A. Variation in blood pressure among individuals
B. Variation in beak shape among finches
C. Differences in fur color in rabbits
D. Variation in leaf shape in plants

The correct answer is (A) Variation in blood pressure among individuals.

Explanation:

Physiological variation refers to differences in the functioning of body systems among individuals of the same species. These variations are often related to internal processes and can be influenced by factors such as genetics, environment, or health. For example:

Blood pressure can vary among individuals due to factors like diet, stress, or genetic predisposition.
Other examples of physiological variation include differences in metabolic rate, enzyme activity, or hormone levels.

Why not the others?

(B) Variation in beak shape among finches: This is an example of morphological variation, which refers to differences in physical structures or forms.
(C) Differences in fur color in rabbits: This is also an example of morphological variation, as it involves physical traits.
(D) Variation in leaf shape in plants: This is another example of morphological variation, as it pertains to the physical structure of leaves.

Thus, variation in blood pressure is an example of physiological variation.

11. Which of the following are components of the skeletal system in humans?

A. Cartilage and blood vessels
B. Ligaments and tendons
C. Muscles and nerves
D. Bones and joints

The correct answer is (D) Bones and joints.

Explanation:

The skeletal system in humans is primarily composed of bones and joints. These structures work together to provide support, protection, and movement for the body. Bones serve as the framework, while joints allow for flexibility and mobility by connecting bones.

Why not the others?

(A) Cartilage and blood vessels: While cartilage is part of the skeletal system (e.g., in joints and the rib cage), blood vessels are part of the circulatory system.
(B) Ligaments and tendons: Ligaments connect bones to other bones at joints, and tendons connect muscles to bones. While they are associated with the skeletal system, they are not its primary components.
(C) Muscles and nerves: Muscles are part of the muscular system, and nerves are part of the nervous system. They work closely with the skeletal system but are not components of it.

Thus, the primary components of the skeletal system are bones and joints.

12. Which of the following represents an example of ecological management and conservation through a biological association?

A. Construction of a dam for hydroelectric power
B. Introduction of an invasive species for pest control
C. Clear-cutting of a forest for timber extraction
D. Establishment of marine protected areas

The correct answer is (D) Establishment of marine protected areas.

Explanation:

Ecological management and conservation aim to protect and sustainably manage ecosystems and biodiversity. The establishment of marine protected areas (MPAs) is a prime example of this. MPAs are designated regions in oceans, seas, or other water bodies where human activities like fishing, mining, and tourism are regulated or restricted to conserve marine life and habitats. This helps:

Protect endangered species.
Preserve biodiversity.
Restore damaged ecosystems.
Promote sustainable use of marine resources.

Why not the others?

(A) Construction of a dam for hydroelectric power: While dams can provide renewable energy, they often disrupt ecosystems, alter water flow, and harm aquatic species, making them more of an ecological challenge than a conservation effort.
(B) Introduction of an invasive species for pest control: Introducing invasive species can lead to unintended ecological consequences, such as outcompeting native species and disrupting ecosystems. This is generally not considered a conservation strategy.
(C) Clear-cutting of a forest for timber extraction: Clear-cutting destroys habitats, reduces biodiversity, and can lead to soil erosion and other environmental issues. It is not a conservation practice.

Thus, the establishment of marine protected areas is a clear example of ecological management and conservation.

13. The term cell was given by

A. Robert Hooke
B. Schwann
C. De Bary
D. Tatum

The correct answer is (A) Robert Hooke.

Explanation:

The term “cell” was first coined by Robert Hooke in 1665. While observing a thin slice of cork under a primitive microscope, Hooke noticed tiny, box-like structures that reminded him of the small rooms or “cells” in a monastery. He described these structures in his book Micrographia and named them “cells.” Although Hooke was observing dead plant cells (the cell walls of cork), his discovery marked the beginning of cell biology.

Why not the others?

(B) Schwann: Theodor Schwann, along with Matthias Schleiden, proposed the cell theory in 1839, stating that all living organisms are composed of cells. However, he did not coin the term “cell.”
(C) De Bary: Anton de Bary was a botanist known for his work on fungi and plant pathology, but he did not introduce the term “cell.”
(D) Tatum: Edward Tatum was a geneticist who contributed to the “one gene, one enzyme” hypothesis, but he had no connection to the term “cell.”

Thus, the term “cell” was given by Robert Hooke.

14. Which of the following is the primary organ involved in gas exchange during respiration in humans?

A. Diaphragm
B. Bronchi
C. Lungs
D. Trachea

The correct answer is (C) Lungs.

Explanation:

The lungs are the primary organs involved in gas exchange during respiration in humans. They contain millions of tiny air sacs called alveoli, where the exchange of oxygen (O₂) and carbon dioxide (CO₂) takes place. Oxygen from inhaled air diffuses into the bloodstream, while carbon dioxide, a waste product, diffuses from the blood into the alveoli to be exhaled.

Why not the others?

(A) Diaphragm: The diaphragm is a muscle that plays a crucial role in breathing by contracting and relaxing to change the volume of the thoracic cavity. However, it is not directly involved in gas exchange.
(B) Bronchi: The bronchi are the main passageways that carry air into the lungs, but they do not participate in gas exchange.
(D) Trachea: The trachea (windpipe) is a tube that connects the larynx to the bronchi, allowing air to pass in and out of the lungs. Like the bronchi, it is not involved in gas exchange.

Thus, the lungs are the primary organs responsible for gas exchange during respiration.

15. Which gland is responsible for producing the hormone insulin?

A. Thyroid gland
B. Pituitary gland
C. Pancreas
D. Adrenal gland

The correct answer is (C) Pancreas.

Explanation:

The pancreas is responsible for producing the hormone insulin. Insulin is a critical hormone that regulates blood sugar (glucose) levels by facilitating the uptake of glucose into cells for energy or storage. The pancreas contains specialized clusters of cells called islets of Langerhans, which include beta cells that produce and secrete insulin.

Why not the others?

(A) Thyroid gland: The thyroid gland produces hormones like thyroxine (T4) and triiodothyronine (T3), which regulate metabolism, but it does not produce insulin.
(B) Pituitary gland: The pituitary gland is often called the “master gland” because it controls other endocrine glands. It produces hormones like growth hormone and prolactin, but not insulin.
(D) Adrenal gland: The adrenal glands produce hormones like adrenaline (epinephrine) and cortisol, which are involved in stress responses and metabolism, but they do not produce insulin.

Thus, the pancreas is the gland responsible for producing insulin.

16. Most fishes do not sink in water because of the presences of:
I. swim bladder
II. air bladder
III. air sacs
IV. air in spongy bones

A. II and III are correct
B. I and II are correct
C. I, II, III and IV are correct
D. III and IV are correct

The correct answer is (B) I and II are correct.

Explanation:

Most fishes maintain buoyancy in water due to the presence of a swim bladder (also called an air bladder). This gas-filled organ helps fish control their buoyancy by adjusting the amount of gas inside it, allowing them to float at different depths without sinking or rising uncontrollably.

Why not the others?

(I) Swim bladder: Correct. This is the primary organ responsible for buoyancy in most bony fishes.
(II) Air bladder: Correct. This is another name for the swim bladder.
(III) Air sacs: Incorrect. Air sacs are not present in fishes; they are found in birds and some other animals to aid in respiration.
(IV) Air in spongy bones: Incorrect. Fishes do not have spongy bones filled with air. This feature is found in birds, not fishes.

Thus, the correct answer is (B) I and II are correct, as the swim bladder and air bladder are the same structure responsible for buoyancy in fishes.

17. In monohybrid inheritance, if an organism carries two different alleles for a particular gene, it is called:

A. Homozygous
B. Dominant
C. Heterozygous
D. Recessive

The correct answer is (C) Heterozygous.

Explanation:

In monohybrid inheritance, an organism’s genotype refers to the combination of alleles it carries for a particular gene. If an organism carries two different alleles for a gene, it is called heterozygous. For example, in pea plants, if one allele codes for tallness (T) and the other for shortness (t), a plant with the genotype Tt is heterozygous.

Why not the others?

(A) Homozygous: This refers to an organism carrying two identical alleles for a gene (e.g., TT or tt).
(B) Dominant: This refers to an allele that is expressed in the phenotype even if only one copy is present (e.g., T in Tt).
(D) Recessive: This refers to an allele that is only expressed in the phenotype if two copies are present (e.g., t in tt).

Thus, an organism carrying two different alleles for a gene is heterozygous.

18. What is the tissue responsible for transporting water and minerals from the roots to the rest of the plant?

A. Xylem
B. Epidermis
C. Parenchyma
D. Phloem

The correct answer is (A) Xylem.

Explanation:

The xylem is the specialized plant tissue responsible for transporting water and minerals from the roots to the rest of the plant. It consists of hollow, tube-like structures made of dead cells that form a continuous pathway for upward movement. Xylem also provides structural support to the plant.

Why not the others?

(B) Epidermis: The epidermis is the outermost layer of cells in plants, primarily serving as a protective barrier. It is not involved in water and mineral transport.
(C) Parenchyma: Parenchyma cells are involved in storage, photosynthesis, and secretion, but they do not transport water and minerals.
(D) Phloem: The phloem is responsible for transporting sugars and other organic nutrients (like amino acids) from the leaves to other parts of the plant, not water and minerals.

Thus, the xylem is the tissue responsible for transporting water and minerals in plants.

19. Which of the following is an example of an abiotic ecological factor?

A. Temperature
B. Competition
C. Predation
D. Symbiosis

The correct answer is (A) Temperature.

Explanation:

Abiotic factors are non-living components of an ecosystem that influence living organisms. These include physical and chemical factors such as:

Temperature
Light
Water
Soil
Air
pH

Temperature is a classic example of an abiotic factor because it affects the survival, reproduction, and distribution of organisms in an ecosystem.

Why not the others?

(B) Competition: This is a biotic factor because it involves interactions between living organisms (e.g., competing for resources like food or space).
(C) Predation: This is also a biotic factor because it involves one organism (the predator) feeding on another (the prey).
(D) Symbiosis: This is a biotic factor because it involves close relationships between different species (e.g., mutualism, commensalism, or parasitism).

Thus, temperature is an example of an abiotic ecological factor.

20. Which of the following processes is involved in the reproduction of developing organisms?

A. Budding
B. Germination
C. Fertilization
D. Pollination

The correct answer is (C) Fertilization.

Explanation:

Fertilization is the process in which male and female gametes (sperm and egg) fuse to form a zygote, which develops into a new organism. This process is essential for sexual reproduction in both plants and animals.

Why not the others?

(A) Budding: This is a form of asexual reproduction where a new organism develops from an outgrowth of the parent organism. It is not involved in the fusion of gametes.
(B) Germination: This is the process by which a seed develops into a new plant. While it is part of the life cycle of plants, it occurs after fertilization and is not directly involved in the fusion of gametes.
(D) Pollination: This is the transfer of pollen from the male part of a flower to the female part, leading to fertilization. While pollination is a crucial step in the reproductive process of flowering plants, it is not the actual fusion of gametes.

Thus, fertilization is the process directly involved in the reproduction of developing organisms.

21. Behavioral adaptation for dealing with a hot climate could include

A. Hibernating during the hottest part of the day
B. Large scales on the back of a lizard
C. Feeding during the hottest part of the day
D. A small kidney to conserve water

The correct answer is (A) Hibernating during the hottest part of the day.

Explanation:

Behavioral adaptations are actions or behaviors that organisms adopt to survive in their environment. In hot climates, many animals avoid the extreme heat by becoming less active during the hottest part of the day, a behavior known as estivation (similar to hibernation but for heat). For example:

Some desert animals, like certain rodents or reptiles, burrow underground and remain inactive during the day to conserve water and energy.
They become active during cooler periods, such as early morning or evening.

Why not the others?

(B) Large scales on the back of a lizard: This is a physical adaptation (structural feature) that helps reduce water loss or protect against predators, not a behavioral adaptation.
(C) Feeding during the hottest part of the day: This is unlikely, as most animals in hot climates avoid activity during peak heat to conserve energy and water.
(D) A small kidney to conserve water: This is a physiological adaptation (internal function) rather than a behavioral one.

Thus, hibernating during the hottest part of the day is a behavioral adaptation for dealing with a hot climate.

22. The natural place of an organism or community is known as

A. Niche
B. Habit
C. Biome
D. Habitat

The correct answer is (D) Habitat.

Explanation:

The habitat is the natural environment or place where an organism or community lives. It includes all the physical and biological factors that characterize the area, such as climate, soil, water, and other organisms. For example:

The habitat of a lion is the savanna.
The habitat of a fish is a freshwater lake or ocean.

Why not the others?

(A) Niche: A niche refers to the role or function of an organism within its habitat, including its behavior, diet, and interactions with other species. It is not the physical place but rather how the organism fits into its environment.
(B) Habit: This term refers to the behavioral patterns of an organism, not its physical environment.
(C) Biome: A biome is a large-scale community of plants and animals defined by a specific climate and vegetation type (e.g., desert, rainforest). While related, it is broader than a habitat.

23. Which process in the nutrient cycle converts atmospheric nitrogen into a form that plants can utilize?

A. Denitrification
B. Nitrogen fixation
C. Ammonification
D. Nitrification

The correct answer is (B) Nitrogen fixation.

Explanation:

Nitrogen fixation is the process by which atmospheric nitrogen (N₂) is converted into a form that plants can use, such as ammonia (NH₃) or nitrates (NO₃⁻). This process is essential because plants cannot use atmospheric nitrogen directly. Nitrogen fixation can occur:

Biologically: Through symbiotic bacteria (e.g., Rhizobium) in the root nodules of legumes.
Industrially: Through the Haber-Bosch process to produce fertilizers.
Physically: Through lightning, which converts nitrogen into nitrates.

Why not the others?

(A) Denitrification: This process converts nitrates (NO₃⁻) back into atmospheric nitrogen (N₂), returning it to the air. It does not make nitrogen available to plants.
(C) Ammonification: This is the process by which decomposers break down organic nitrogen (e.g., from dead plants and animals) into ammonia (NH₃). While it produces a usable form of nitrogen, it does not involve atmospheric nitrogen.
(D) Nitrification: This process converts ammonia (NH₃) into nitrites (NO₂⁻) and then into nitrates (NO₃⁻), which plants can absorb. However, it does not start with atmospheric nitrogen.

24. Which of the following functions is performed by the skin to help maintain homeostasis in the human body?

A. Regulation of body temperature
B. Filtration of blood
C. Production of hormones
D. Digestion of food

The correct answer is (A) Regulation of body temperature.

Explanation:

The skin plays a critical role in maintaining homeostasis (the body’s internal balance) by regulating body temperature. This is achieved through:

Sweating: When the body is too hot, sweat glands produce sweat, which evaporates and cools the skin.
Vasodilation: Blood vessels near the skin’s surface widen to release heat.
Vasoconstriction: Blood vessels narrow to conserve heat when the body is cold.
Goosebumps: Tiny muscles in the skin contract to trap heat when it’s cold.

ALSO READ: JAMB Biology 1981 Past Questions

Why not the others?

(B) Filtration of blood: This is performed by the kidneys, not the skin.
(C) Production of hormones: Hormones are produced by endocrine glands (e.g., thyroid, adrenal glands), not the skin.
(D) Digestion of food: Digestion is carried out by the digestive system, including the stomach and intestines.

Thus, the skin helps maintain homeostasis primarily by regulating body temperature.

25. Which of the following soil types becomes less fertile due to the intense leaching caused by tropical rains?

A. Yellow soil
B. Laterite soil
C. Red soils
D. Black soil

The correct answer is (B) Laterite soil.

Explanation:

Laterite soil is a type of soil found in tropical regions with heavy rainfall. Due to intense leaching caused by tropical rains, nutrients like silica, calcium, and magnesium are washed away, leaving behind iron and aluminum oxides. This process makes laterite soil:

Less fertile: The loss of essential nutrients reduces its ability to support plant growth.
Hard and compact: When dry, it becomes brick-like and difficult to cultivate.

Why not the others?

(A) Yellow soil: This soil is typically found in temperate regions and is not as heavily affected by leaching as laterite soil.
(C) Red soils: These soils are rich in iron oxides and are generally fertile, especially in subtropical regions. They are not as prone to nutrient loss as laterite soil.
(D) Black soil: Also known as regur soil, it is highly fertile and retains moisture well. It is commonly found in regions with moderate rainfall and is not significantly affected by leaching.

Thus, laterite soil becomes less fertile due to intense leaching caused by tropical rains.

26. Which type of reproduction involves the fusion of gametes from two parents?

A. Sexual reproduction
B. Asexual reproduction
C. Binary fission
D. Budding

The correct answer is (A) Sexual reproduction.

Explanation:

Sexual reproduction involves the fusion of gametes (reproductive cells) from two parents—a male gamete (sperm) and a female gamete (egg). This process results in offspring that are genetically distinct from both parents due to the combination of genetic material. Key features of sexual reproduction include:

Formation of gametes through meiosis.
Fertilization, where the gametes fuse to form a zygote.
Genetic diversity in offspring.

Why not the others?

(B) Asexual reproduction: This involves a single parent producing genetically identical offspring without the fusion of gametes. Examples include binary fission, budding, and vegetative propagation.
(C) Binary fission: This is a form of asexual reproduction where a single organism divides into two identical daughter cells (e.g., in bacteria).
(D) Budding: This is another form of asexual reproduction where a new organism grows out of the parent organism (e.g., in hydra or yeast).

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

27. Which processes are involved in nutrient cycling in a functioning ecosystem?

A. Erosion, weathering, and sedimentation
B. Decomposition, evaporation, and precipitation
C. Nitrogen fixation, denitrification, and ammonification
D. Respiration, photosynthesis, and transpiration

The correct answer is (C) Nitrogen fixation, denitrification, and ammonification.

Explanation:

Nutrient cycling refers to the movement and exchange of essential nutrients (like carbon, nitrogen, and phosphorus) through biotic (living) and abiotic (non-living) components of an ecosystem. The processes listed in option (C) are all part of the nitrogen cycle, which is a critical component of nutrient cycling:

Nitrogen fixation: Converts atmospheric nitrogen (N₂) into ammonia (NH₃), making it usable for plants.
Denitrification: Converts nitrates (NO₃⁻) back into atmospheric nitrogen (N₂), completing the cycle.
Ammonification: Converts organic nitrogen (from dead organisms and waste) into ammonia (NH₃), which can then be used by plants or further processed.

Why not the others?

(A) Erosion, weathering, and sedimentation: These are geological processes that affect soil formation and nutrient availability but are not directly part of nutrient cycling in ecosystems.
(B) Decomposition, evaporation, and precipitation: While decomposition is part of nutrient cycling, evaporation and precipitation are part of the water cycle, not nutrient cycling.
(D) Respiration, photosynthesis, and transpiration: These are important biological processes, but they are primarily involved in the carbon cycle and water cycle, not the broader nutrient cycling processes.

Thus, nitrogen fixation, denitrification, and ammonification are key processes involved in nutrient cycling in a functioning ecosystem.

29. What is autotrophic nutrition?

A. Nutrition in which organisms obtain food by breaking down complex organic compounds.
B. Nutrition in which organisms obtain food from other organisms
C. Nutrition in which organisms obtain food by consuming both plants and animals
D. Nutrition in which organisms produce their own food using energy from the sun or inorganic substances

The correct answer is (D) Nutrition in which organisms produce their own food using energy from the sun or inorganic substances.

Explanation:

Autotrophic nutrition is a mode of nutrition in which organisms produce their own food using energy from sunlight (through photosynthesis) or inorganic substances (through chemosynthesis). These organisms are called autotrophs and form the base of the food chain. Examples include:

Plants: Use sunlight, carbon dioxide, and water to produce glucose through photosynthesis.
Cyanobacteria: Also perform photosynthesis.
Chemosynthetic bacteria: Use inorganic compounds like hydrogen sulfide to produce energy in environments without sunlight (e.g., deep-sea vents).

Why not the others?

(A) Nutrition in which organisms obtain food by breaking down complex organic compounds: This describes saprophytic nutrition, seen in fungi and some bacteria.
(B) Nutrition in which organisms obtain food from other organisms: This describes heterotrophic nutrition, seen in animals, fungi, and some bacteria.
(C) Nutrition in which organisms obtain food by consuming both plants and animals: This describes omnivorous nutrition, a type of heterotrophic nutrition.

Thus, autotrophic nutrition involves organisms producing their own food using energy from the sun or inorganic substances.

29. The theory of evolution can be defined as

A. The belief that all species were created in their current form
B. The hypothesis that organisms strive to improve themselves over generations
C. The idea that species change over time through natural processes
D. The concept that evolution occurs through a series of sudden and dramatic changes

The correct answer is (C) The idea that species change over time through natural processes.

Explanation:

The theory of evolution is a scientific explanation for how species change over time through natural processes. Key concepts include:

Natural selection: Proposed by Charles Darwin, this is the process by which organisms with traits better suited to their environment are more likely to survive and reproduce, passing those traits to the next generation.
Genetic variation: Differences in DNA among individuals in a population, which provide the raw material for evolution.
Common ancestry: All living organisms share a common ancestor, and species diverge over time through evolutionary processes.

Why not the others?

(A) The belief that all species were created in their current form: This describes creationism, not the scientific theory of evolution.
(B) The hypothesis that organisms strive to improve themselves over generations: This is incorrect because evolution is not goal-directed; it is driven by random mutations and natural selection.
(D) The concept that evolution occurs through a series of sudden and dramatic changes: This describes saltationism, which is not supported by the gradual changes observed in the fossil record and genetic evidence.

Thus, the theory of evolution is best defined as the idea that species change over time through natural processes.

30. Which of the following is a male reproductive organ in humans?

A. Uterus
B. Ovary
C. Testis
D. Fallopian tube

The correct answer is (C) Testis.

Explanation:

The testis (plural: testes) is the primary male reproductive organ in humans. It has two main functions:

Production of sperm: The testes produce male gametes (sperm) through a process called spermatogenesis.
Secretion of testosterone: The testes produce the male sex hormone testosterone, which regulates male secondary sexual characteristics and reproductive functions.

Why not the others?

(A) Uterus: This is a female reproductive organ where a fertilized egg implants and develops into a fetus.
(B) Ovary: This is a female reproductive organ that produces eggs (ova) and secretes hormones like estrogen and progesterone.
(D) Fallopian tube: This is a female reproductive structure that transports eggs from the ovary to the uterus and is the site of fertilization.

Thus, the testis is the male reproductive organ.

31. Which of the following is an example of a behavioral adaptation for survival in animals?

A. Sharp teeth
B. Migration
C. Wings
D. Camouflage

The correct answer is (B) Migration.

Explanation:

Behavioral adaptations are actions or behaviors that animals adopt to survive and thrive in their environment. Migration is a classic example of a behavioral adaptation, where animals move from one region to another in response to seasonal changes, food availability, or breeding needs. For example:

Birds like the Arctic tern migrate thousands of miles between breeding and wintering grounds.
Wildebeests in Africa migrate in search of fresh grazing areas.

Why not the others?

(A) Sharp teeth: This is a physical adaptation (structural feature) that helps animals tear or grind food, not a behavior.
(C) Wings: This is also a physical adaptation that enables flight in birds, bats, and insects.
(D) Camouflage: This is a physical adaptation where an organism’s appearance helps it blend into its environment to avoid predators or ambush prey.

Thus, migration is an example of a behavioral adaptation for survival in animals.

32. Which of the following traits is not visible in a person with Down syndrome?

A. Short neck
B. High muscle tone
C. Small stature
D. Slant eyes

The correct answer is (B) High muscle tone.

Explanation:

Down syndrome is a genetic condition caused by the presence of an extra chromosome 21 (trisomy 21). It is associated with several physical and developmental traits, including:

Short neck: A common physical characteristic.
Small stature: Individuals with Down syndrome are often shorter in height.
Slant eyes: Upward-slanting eyes with epicanthic folds are a typical facial feature.

However, high muscle tone (hypertonia) is not a characteristic of Down syndrome. In fact, individuals with Down syndrome often have low muscle tone (hypotonia), which can affect motor skills and development.

Why not the others?

(A) Short neck, (C) Small stature, and (D) Slant eyes are all visible traits commonly associated with Down syndrome.

Thus, high muscle tone is not a trait seen in individuals with Down syndrome.

33. What is the definition of population ecology?

A. The study of interactions between organisms and their physical environment
B. The study of evolutionary processes and their effects on populations
C. The study of interactions between different populations in an ecosystem
D. The study of the distribution and abundance of individuals within a species

The correct answer is (D) The study of the distribution and abundance of individuals within a species.

Explanation:

Population ecology is a branch of ecology that focuses on the distribution (where individuals are located) and abundance (how many individuals exist) of a particular species within a specific area. It also examines factors that influence population dynamics, such as:

Birth and death rates.
Immigration and emigration.
Resource availability.
Interactions with other species and the environment.

Why not the others?

(A) The study of interactions between organisms and their physical environment: This describes ecosystem ecology or environmental ecology, not population ecology.
(B) The study of evolutionary processes and their effects on populations: This describes evolutionary ecology or population genetics, not population ecology.
(C) The study of interactions between different populations in an ecosystem: This describes community ecology, which focuses on interactions between multiple species, not a single population.

Thus, population ecology is defined as the study of the distribution and abundance of individuals within a species.

34. What is the term used to describe the maximum number of individuals of a species that an environment can support indefinitely?

A. Ecological niche
B. Limiting factor
C. Carrying capacity
D. Density-dependent factor

The correct answer is (C) Carrying capacity.

Explanation:

Carrying capacity refers to the maximum number of individuals of a species that an environment can support indefinitely without degrading the environment. It is determined by factors such as:

Availability of resources (food, water, shelter).
Space.
Disease.
Predation.
Competition.

When a population exceeds its carrying capacity, it may lead to resource depletion, increased mortality, or emigration.

Why not the others?

(A) Ecological niche: This refers to the role or function of an organism in its ecosystem, including its habitat, behavior, and interactions, not the population size it can support.
(B) Limiting factor: This is any factor (biotic or abiotic) that restricts the growth, abundance, or distribution of a population, but it does not describe the maximum population size.
(D) Density-dependent factor: These are factors (e.g., disease, competition) whose effects on a population increase as the population density increases, but they do not define the maximum population size.

Thus, carrying capacity is the term used to describe the maximum number of individuals an environment can support indefinitely.

35. Which of the following statements about the heart is true?

A. The heart is responsible for the production of red blood cells
B. The heart pumps oxygenated blood to the lungs
C. The heart receives blood from the kidneys and filters waste products
D. The heart is a muscular organ that contracts to circulate blood throughout the body

The correct answer is (D) The heart is a muscular organ that contracts to circulate blood throughout the body.

Explanation:

The heart is a muscular organ that functions as the central pump of the circulatory system. Its primary role is to contract rhythmically to circulate blood throughout the body, delivering oxygen and nutrients to tissues and removing waste products. Key features of the heart include:

Four chambers: Two atria (upper chambers) and two ventricles (lower chambers).
Valves: Prevent backflow of blood.
Electrical system: Controls the heartbeat (e.g., sinoatrial node).

Why not the others?

(A) The heart is responsible for the production of red blood cells: This is incorrect. Red blood cells are produced in the bone marrow, not the heart.
(B) The heart pumps oxygenated blood to the lungs: This is incorrect. The heart pumps deoxygenated blood to the lungs for oxygenation and receives oxygenated blood from the lungs to pump to the rest of the body.
(C) The heart receives blood from the kidneys and filters waste products: This is incorrect. The kidneys filter waste products from the blood, but the heart does not perform this function.

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

36. What is the primary source of variation in a population?

A. Gene flow
B. Mutation
C. Natural selection
D. Genetic drift

The correct answer is (B) Mutation.

Explanation:

Mutation is the primary source of genetic variation in a population. Mutations are random changes in the DNA sequence of an organism’s genome, and they can create new alleles (versions of a gene). These new alleles can lead to new traits, which may be beneficial, neutral, or harmful. Over time, mutations provide the raw material for evolution by natural selection, genetic drift, and other evolutionary processes.

Why not the others?

(A) Gene flow: This refers to the movement of genes between populations through migration. While it introduces variation, it is not the primary source.
(C) Natural selection: This is a process that acts on existing variation to favor traits that improve survival and reproduction, but it does not create new variation.
(D) Genetic drift: This is a random change in allele frequencies in a population, but it does not create new alleles or variation.

Thus, mutation is the primary source of variation in a population.

37. Which component of blood is responsible for carrying oxygen to the body tissues?

A. Platelets
B. White blood cells
C. Red blood cells
D. Plasma

The correct answer is (C) Red blood cells.

Explanation:

Red blood cells (RBCs), also called erythrocytes, are the component of blood responsible for carrying oxygen to the body tissues. They contain a protein called hemoglobin, which binds to oxygen in the lungs and transports it to cells throughout the body. RBCs also help carry carbon dioxide, a waste product, back to the lungs for exhalation.

Why not the others?

(A) Platelets: These are cell fragments involved in blood clotting and wound healing, not oxygen transport.
(B) White blood cells: These are part of the immune system and defend the body against infections, but they do not carry oxygen.
(D) Plasma: This is the liquid component of blood that carries nutrients, hormones, and waste products, but it does not transport oxygen.

Thus, red blood cells are responsible for carrying oxygen to the body tissues.

38. What are the primary products of photosynthesis?

A. Carbon dioxide and water
B. Glucose and oxygen
C. Glucose and carbon dioxide
D. Oxygen and water

The correct answer is (B) Glucose and oxygen.

Explanation:

Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy. The overall equation for photosynthesis is:

Carbon dioxide (CO₂) and water (H₂O) are the reactants.
Glucose (C₆H₁₂O₆) and oxygen (O₂) are the primary products.

Glucose serves as an energy source for the plant, while oxygen is released into the atmosphere as a byproduct.

Why not the others?

(A) Carbon dioxide and water: These are the reactants, not the products.
(C) Glucose and carbon dioxide: Carbon dioxide is a reactant, not a product.
(D) Oxygen and water: Water is a reactant, not a product.

Thus, the primary products of photosynthesis are glucose and oxygen.

39. The alternate form of a gene is

A. Alternate type
B. Dominant character
C. Recessive character
D. Allele

The correct answer is (D) Allele.

Explanation:

An allele is an alternate form of a gene that occurs at a specific location (locus) on a chromosome. Alleles determine variations in inherited traits. For example:

In pea plants, the gene for flower color has two alleles: one for purple flowers and one for white flowers.
Alleles can be dominant (expressed when present) or recessive (expressed only when two copies are present).

Why not the others?

(A) Alternate type: This is not a scientific term used in genetics.
(B) Dominant character: This refers to a trait expressed when at least one dominant allele is present, but it is not the alternate form of a gene.
(C) Recessive character: This refers to a trait expressed only when two recessive alleles are present, but it is not the alternate form of a gene.

Thus, the alternate form of a gene is called an allele.

40. Which organs are part of the alimentary canal in the human digestive system?

A. Salivary glands, tongue, and pharynx
B. Large intestine, appendix, and rectum
C. Stomach, liver, and gallbladder
D. Oesophagus, pancreas, and small intestine

The correct answer is (B) Large intestine, appendix, and rectum.

Explanation:

Mouth
Pharynx
Oesophagus
Stomach
Small intestine
Large intestine (including the appendix)
Rectum
Anus

The large intestine, appendix, and rectum are all part of the alimentary canal.

Why not the others?

(A) Salivary glands, tongue, and pharynx: While the pharynx is part of the alimentary canal, the salivary glands and tongue are accessory organs that aid in digestion but are not part of the canal itself.
(C) Stomach, liver, and gallbladder: The stomach is part of the alimentary canal, but the liver and gallbladder are accessory organs that produce and store bile, respectively.
(D) Oesophagus, pancreas, and small intestine: The oesophagus and small intestine are part of the alimentary canal, but the pancreas is an accessory organ that produces digestive enzymes and hormones.

Thus, the large intestine, appendix, and rectum are all part of the alimentary canal.

41. Which of the following characteristics is typical of the phylum Arthropoda?

A. Radial symmetry
B. Closed circulatory system
C. Endoskeleton made of bones
D. Presence of a segmented body

The correct answer is (D) Presence of a segmented body.

Explanation:

The phylum Arthropoda is the largest and most diverse phylum in the animal kingdom, including insects, spiders, crustaceans, and millipedes. Key characteristics of arthropods include:

Segmented body: The body is divided into distinct segments, often grouped into regions like the head, thorax, and abdomen.
Exoskeleton: Made of chitin, providing support and protection.
Jointed appendages: Legs, antennae, and mouthparts are jointed and specialized for various functions.
Open circulatory system: Blood is not entirely contained within blood vessels.

Why not the others?

(A) Radial symmetry: This is characteristic of phyla like Cnidaria (e.g., jellyfish) and Echinodermata (e.g., starfish), not arthropods.
(B) Closed circulatory system: Arthropods have an open circulatory system, where blood flows freely in body cavities.
(C) Endoskeleton made of bones: Arthropods have an exoskeleton, not an endoskeleton. Vertebrates (e.g., mammals, birds) have endoskeletons made of bones.

Thus, the presence of a segmented body is a typical characteristic of the phylum Arthropoda.

42. Which of the following is an example of conserving resources in an ecosystem

A. Excessive use of chemical fertilizers in agriculture
B. Introducing invasive species to an ecosystem
C. Implementing sustainable fishing practices
D. Cutting down trees for timber production

The correct answer is (C) Implementing sustainable fishing practices.

Explanation:

Conserving resources in an ecosystem involves using natural resources in a way that ensures their availability for future generations while maintaining ecological balance. Sustainable fishing practices are an example of this because they aim to:

Prevent overfishing.
Protect fish populations and their habitats.
Maintain the health of marine ecosystems.

Examples of sustainable fishing practices include setting catch limits, using selective fishing gear, and establishing marine protected areas.

Why not the others?

(A) Excessive use of chemical fertilizers in agriculture: This can lead to soil degradation, water pollution, and harm to ecosystems, making it unsustainable.
(B) Introducing invasive species to an ecosystem: This often disrupts native species and ecosystems, leading to biodiversity loss and resource depletion.
(D) Cutting down trees for timber production: Without sustainable management, this can lead to deforestation, habitat loss, and ecosystem degradation.

Thus, implementing sustainable fishing practices is an example of conserving resources in an ecosystem.

43. Which of the following represents the correct hierarchical organization of life from the smallest to the largest scale?

A. Organs, tissues, cells, organisms, populations, communities, ecosystems
B. Cells, organs, tissues, organisms, populations, communities, ecosystems
C. Tissues, organs, cells, organisms, populations, communities, ecosystems
D. Cells, tissues, organs, organisms, populations, communities, ecosystems

The correct answer is (D) Cells, tissues, organs, organisms, populations, communities, ecosystems.

Explanation:

The hierarchical organization of life progresses from the smallest and simplest units to the largest and most complex systems. Here’s the correct order:

Cells: The basic structural and functional units of life.
Tissues: Groups of similar cells working together to perform a specific function.
Organs: Structures made up of different tissues that work together to perform a specific function.
Organisms: Individual living beings composed of multiple organ systems.
Populations: Groups of organisms of the same species living in the same area.
Communities: Multiple populations of different species living and interacting in the same area.
Ecosystems: Communities of organisms interacting with their physical environment.

Why not the others?

(A) Organs, tissues, cells, organisms, populations, communities, ecosystems: This is incorrect because cells are the smallest unit, not organs.
(B) Cells, organs, tissues, organisms, populations, communities, ecosystems: This is incorrect because tissues come before organs.
(C) Tissues, organs, cells, organisms, populations, communities, ecosystems: This is incorrect because cells are the smallest unit, not tissues.

Thus, the correct hierarchical organization is cells, tissues, organs, organisms, populations, communities, ecosystems.

44. Which of the following blood vessels carries oxygenated blood away from the heart?

A. Arteries
B. Venules
C. Capillaries
D. Veins

The correct answer is (A) Arteries.

Explanation:

Arteries are blood vessels that carry oxygenated blood away from the heart to the rest of the body. The only exception is the pulmonary artery, which carries deoxygenated blood from the heart to the lungs. Key features of arteries include:

Thick, muscular walls to withstand high pressure.
Elasticity to accommodate blood flow from the heart.

Why not the others?

(B) Venules: These are small veins that carry deoxygenated blood from capillaries to larger veins.
(C) Capillaries: These are tiny blood vessels where the exchange of oxygen, nutrients, and waste products occurs between blood and tissues. They connect arteries and veins.
(D) Veins: These carry deoxygenated blood back to the heart (except for the pulmonary veins, which carry oxygenated blood from the lungs to the heart).

Thus, arteries are the blood vessels that carry oxygenated blood away from the heart.

45. Which of the following factors primarily affects the distribution of organisms in an ecosystem

A. Wind speed
B. Soil pH
C. Temperature
D. Day length

The correct answer is (C) Temperature.

Explanation:

Temperature is one of the most important factors affecting the distribution of organisms in an ecosystem. It influences:

Metabolic rates: Most organisms have a specific temperature range in which they can survive and function optimally.
Reproduction: Temperature can affect breeding cycles and the survival of offspring.
Habitat suitability: Different species are adapted to specific temperature ranges, which determines where they can live (e.g., polar bears in cold climates, cacti in hot deserts).

Why not the others?

(A) Wind speed: While wind can affect certain organisms (e.g., plants by dispersing seeds), it is not a primary factor in determining the overall distribution of organisms.
(B) Soil pH: This is important for plants and soil-dwelling organisms, but it is not as universally influential as temperature.
(D) Day length: Day length (photoperiod) affects behaviors like migration and flowering in some species, but it is not as broadly impactful as temperature.

Thus, temperature is the primary factor affecting the distribution of organisms in an ecosystem.

46. Which of the following is NOT a method of reproduction in animals?

A. Asexual reproduction
B. Budding
C. Sexual reproduction
D. Sporulation

The correct answer is (D) Sporulation.

Explanation:

Sporulation is a method of reproduction primarily used by fungi, bacteria, and some plants, but it is not a method of reproduction in animals. In sporulation, specialized cells called spores are produced, which can develop into new individuals under favorable conditions.

Why not the others?

(A) Asexual reproduction: This is common in many animals, such as hydra (budding) and starfish (regeneration).
(B) Budding: This is a form of asexual reproduction where a new organism grows out of the parent organism (e.g., hydra).
(C) Sexual reproduction: This is the most common method of reproduction in animals, involving the fusion of male and female gametes.

Thus, sporulation is not a method of reproduction in animals.

47. Which of the following statements is true about the kingdom Fungi?

A. Fungi obtain nutrients by absorbing organic matter
B. Fungi are photosynthetic organisms
C. Fungi are multicellular organisms
D. Fungi reproduce through the formation of seeds

The correct answer is (A) Fungi obtain nutrients by absorbing organic matter.

Explanation:

Fungi are heterotrophic organisms that obtain nutrients by absorbing organic matter from their environment. They secrete digestive enzymes into their surroundings, breaking down complex organic compounds into simpler molecules, which they then absorb. This mode of nutrition is called saprophytic or absorptive nutrition.

Why not the others?

(B) Fungi are photosynthetic organisms: This is incorrect. Fungi are not photosynthetic; they do not contain chlorophyll and cannot produce their own food through photosynthesis.
(C) Fungi are multicellular organisms: While many fungi are multicellular (e.g., mushrooms), some are unicellular (e.g., yeasts). Therefore, this statement is not universally true.
(D) Fungi reproduce through the formation of seeds: This is incorrect. Fungi reproduce through spores, not seeds. Seeds are a reproductive structure found in plants.

Thus, the true statement about the kingdom Fungi is that they obtain nutrients by absorbing organic matter.

48. viviparity refers to the reproductive strategy in which

A. Offspring are produced by internal fertilization
B. Offspring are produced by external fertilization
C. Offspring develop and are nourished inside the female’s body
D. Offspring develop and are nourished outside the female’s body

The correct answer is (C) Offspring develop and are nourished inside the female’s body.

Explanation:

Viviparity is a reproductive strategy in which:

Offspring develop inside the female’s body.
They receive nourishment directly from the mother (usually through a placenta or similar structure).
The young are born live, rather than hatching from eggs outside the body.

This strategy is common in mammals (e.g., humans, dogs) and some reptiles and fish.

Why not the others?

(A) Offspring are produced by internal fertilization: While viviparity involves internal fertilization, this statement does not fully describe viviparity, as it does not mention development inside the female’s body.
(B) Offspring are produced by external fertilization: This describes oviparity (egg-laying) or ovoviviparity (eggs hatch inside the body), not viviparity.
(D) Offspring develop and are nourished outside the female’s body: This describes oviparity, where eggs are laid and develop outside the mother’s body.

Thus, viviparity refers to the reproductive strategy in which offspring develop and are nourished inside the female’s body.

49. Which of the following is the most inclusive level of classification in the Linnaean system?

A. Kingdom
B. Phylum
C. Domain
D. Class

The correct answer is (C) Domain.

Explanation:

In the modern Linnaean system of classification, the domain is the most inclusive (broadest) level of classification. There are three domains:

Bacteria: Prokaryotic organisms with simple cell structures.
Archaea: Prokaryotic organisms often found in extreme environments.
Eukarya: Eukaryotic organisms, including plants, animals, fungi, and protists.

Below the domain level, the hierarchy progresses as follows:
Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species.

Why not the others?

(A) Kingdom: This is a level below domain and includes groups like Animalia, Plantae, and Fungi.
(B) Phylum: This is a level below kingdom and groups organisms based on major body plans (e.g., Chordata in animals).
(D) Class: This is a level below phylum and groups organisms with similar characteristics (e.g., Mammalia in the phylum Chordata).

Thus, the domain is the most inclusive level of classification in the Linnaean system.

50. Which of the following describes the inheritance of traits from parents to offspring?

A. Adaptation
B. Evolution
C. Natural selection
D. Genetics

The correct answer is (D) Genetics.

Explanation:

Genetics is the branch of biology that studies the inheritance of traits from parents to offspring. It focuses on how genes, which are segments of DNA, are passed down through generations and how they influence traits. Key concepts in genetics include:

Mendelian inheritance: Patterns of inheritance discovered by Gregor Mendel.
Chromosomes: Structures that carry genes.
Alleles: Different versions of a gene.

Why not the others?

(A) Adaptation: This refers to traits that improve an organism’s survival and reproduction in a specific environment, but it does not describe the mechanism of inheritance.
(B) Evolution: This is the process by which species change over time through mechanisms like natural selection, mutation, and genetic drift. While it involves genetics, it is broader than just inheritance.
(C) Natural selection: This is a mechanism of evolution where traits that improve survival and reproduction become more common in a population, but it does not describe the process of inheritance.

Thus, genetics describes the inheritance of traits from parents to offspring.

51. Which of the following statements best describes the role of competition in the process of adaptation?

A. Competition leads to the selection of individuals with favorable traits for survival and reproduction
B. Competition ensures equal distribution of resources among individuals in a population
C. Competition leads to the development of new traits and adaptations in a population
D. Competition reduces the need for adaptations as individuals coexist peacefully

The correct answer is (A) Competition leads to the selection of individuals with favorable traits for survival and reproduction.

Explanation:

Competition is a key driver of natural selection, which is the process by which individuals with traits that improve their survival and reproduction are more likely to pass those traits to the next generation. In a competitive environment:

Individuals with favorable traits (e.g., better access to resources, higher resistance to predators) are more likely to survive and reproduce.
Over time, these traits become more common in the population, leading to adaptation.

Why not the others?

(B) Competition ensures equal distribution of resources among individuals in a population: This is incorrect. Competition often leads to unequal access to resources, favoring individuals with advantageous traits.
(C) Competition leads to the development of new traits and adaptations in a population: While competition can drive the selection of existing traits, it does not directly cause the development of new traits. New traits arise through mutations and genetic variation.
(D) Competition reduces the need for adaptations as individuals coexist peacefully: This is incorrect. Competition increases the need for adaptations, as individuals must compete for limited resources.

Thus, competition leads to the selection of individuals with favorable traits for survival and reproduction.

52. Which of the following statements is true regarding sex-linked traits?

A. Sex-linked traits are located on the sex chromosomes
B. Sex-linked traits are inherited only from the mother
C. Sex-linked traits are more commonly observed in females
D. Sex-linked traits are not influenced by hormonal factors

The correct answer is (A) Sex-linked traits are located on the sex chromosomes.

Explanation:

Sex-linked traits are traits determined by genes located on the sex chromosomes (X or Y). In humans:

Most sex-linked traits are X-linked, meaning they are located on the X chromosome.
Examples include color blindness and hemophilia, which are more common in males because males have only one X chromosome (XY), so a single recessive allele on the X chromosome will express the trait. Females (XX) need two copies of the recessive allele to express the trait.

Why not the others?

(B) Sex-linked traits are inherited only from the mother: This is incorrect. While males inherit their X chromosome from their mother, they can also inherit Y-linked traits from their father.
(C) Sex-linked traits are more commonly observed in females: This is incorrect. X-linked recessive traits are more commonly observed in males because they have only one X chromosome.
(D) Sex-linked traits are not influenced by hormonal factors: This is incorrect. Hormonal factors can influence the expression of some sex-linked traits, although the genes themselves are located on the sex chromosomes.

Thus, the true statement is that sex-linked traits are located on the sex chromosomes.

53. Which of the following is a plant hormone responsible for promoting cell elongation and growth?

A. Abscisic acid
B. Gibberellins
C. Ethylene
D. Cytokinins

The correct answer is (B) Gibberellins.

Explanation:

Gibberellins are a group of plant hormones that play a key role in promoting cell elongation and growth. They are involved in various plant processes, including:

Stem elongation.
Seed germination.
Flowering and fruit development.

Gibberellins work by stimulating cell division and elongation, leading to increased plant height and size.

Why not the others?

(A) Abscisic acid: This hormone is involved in stress responses (e.g., drought tolerance) and seed dormancy, not growth promotion.
(C) Ethylene: This hormone regulates fruit ripening, flower wilting, and leaf abscission, but it does not promote cell elongation.
(D) Cytokinins: These hormones promote cell division and lateral bud growth, but they are not primarily responsible for cell elongation.

Thus, gibberellins are the plant hormone responsible for promoting cell elongation and growth.

54. Which of the following is a primary source of pollution in aquatic ecosystems?

A. Soil erosion
B. Industrial discharge
C. Air pollution
D. Deforestation

The correct answer is (B) Industrial discharge.

Explanation:

Industrial discharge is a major source of pollution in aquatic ecosystems. Industries often release harmful substances such as:

Heavy metals (e.g., mercury, lead).
Toxic chemicals (e.g., pesticides, solvents).
Wastewater containing pollutants.

These substances can contaminate water bodies, harm aquatic life, and disrupt ecosystems.

Why not the others?

(A) Soil erosion: While soil erosion can contribute to sedimentation in water bodies, it is not a primary source of chemical pollution.
(C) Air pollution: Air pollution can indirectly affect aquatic ecosystems through acid rain, but it is not a direct source of water pollution.
(D) Deforestation: Deforestation can lead to soil erosion and sedimentation in water bodies, but it is not a direct source of chemical pollution.

Thus, industrial discharge is a primary source of pollution in aquatic ecosystems.

55. Which of the following mechanisms is responsible for providing support in plants?

A. Muscles and bones
B. Exoskeleton
C. Endocrine system
D. Cell walls and turgor pressure

The correct answer is (D) Cell walls and turgor pressure.

Explanation:

Plants rely on cell walls and turgor pressure for support and structure:

Cell walls: Made of cellulose, they provide rigidity and shape to plant cells.
Turgor pressure: The pressure exerted by water inside the cell against the cell wall, which helps maintain the plant’s upright structure.

Together, these mechanisms allow plants to stand upright and support their leaves, stems, and flowers.

Why not the others?

(A) Muscles and bones: These are found in animals, not plants.
(B) Exoskeleton: This is a hard outer structure found in arthropods (e.g., insects, crustaceans), not plants.
(C) Endocrine system: This is a system of glands and hormones found in animals, not plants.

Thus, cell walls and turgor pressure are responsible for providing support in plants.

56. Metamorphosis is a biological process that involves

A. The growth and development of an organism from a zygote to an adult
B. The change in form and structure during the life cycle of certain organisms
C. The regeneration of lost body parts in an organism
D. The transformation of an organism from an adult stage to a larval stage

The correct answer is (B) The change in form and structure during the life cycle of certain organisms.

Explanation:

Metamorphosis is a biological process in which an organism undergoes a dramatic change in form and structure during its life cycle. This process is common in insects (e.g., butterflies, beetles) and amphibians (e.g., frogs). There are two main types of metamorphosis:

Complete metamorphosis: Involves four stages—egg, larva, pupa, and adult (e.g., butterflies).
Incomplete metamorphosis: Involves three stages—egg, nymph, and adult (e.g., grasshoppers).

Why not the others?

(A) The growth and development of an organism from a zygote to an adult: This describes general development, not metamorphosis.
(C) The regeneration of lost body parts in an organism: This is a different process, seen in organisms like starfish and salamanders.
(D) The transformation of an organism from an adult stage to a larval stage: This is incorrect, as metamorphosis involves transitioning from a larval stage to an adult stage, not the reverse.

Thus, metamorphosis involves the change in form and structure during the life cycle of certain organisms.

57. Which of the following organs is primarily responsible for excretion in humans?

A. Liver
B. Pancreas
C. Kidneys
D. Lungs

The correct answer is (C) Kidneys.

Explanation:

The kidneys are the primary organs responsible for excretion in humans. They filter waste products, excess water, and toxins from the blood to produce urine, which is then excreted from the body. The kidneys also help regulate:

Blood pressure.
Electrolyte balance.
pH levels.

Why not the others?

(A) Liver: The liver detoxifies chemicals and metabolizes drugs, but its primary role is not excretion. It produces bile, which aids in digestion.
(B) Pancreas: The pancreas produces digestive enzymes and hormones like insulin, but it is not involved in excretion.
(D) Lungs: The lungs excrete carbon dioxide (a waste product of respiration), but they are not the primary excretory organs.

Thus, the kidneys are primarily responsible for excretion in humans.

58. Which of the following is the correct classification of carbohydrates?

A. Lipid
B. Phytonutrient
C. Macronutrient
D. Micronutrient

The correct answer is (C) Macronutrient.

Explanation:

Carbohydrates are classified as macronutrients, which are nutrients required by the body in large amounts for energy and other functions. The three main macronutrients are:

Carbohydrates: Provide energy (4 calories per gram).
Proteins: Build and repair tissues.
Fats: Provide energy and support cell function.

Carbohydrates are found in foods like grains, fruits, vegetables, and sugars.

Why not the others?

(A) Lipid: Lipids are a separate category of macronutrients that include fats and oils.
(B) Phytonutrient: Phytonutrients are bioactive compounds found in plants, not a classification of carbohydrates.
(D) Micronutrient: Micronutrients are nutrients required in small amounts, such as vitamins and minerals, not carbohydrates.

Thus, carbohydrates are classified as macronutrients.

59. Which of the following eye defects is caused by the inability of the eye to focus light on the retina?

A. Glaucoma
B. Myopia
C. Cataracts
D. Astigmatism

The correct answer is (B) Myopia.

Explanation:

Myopia, also known as nearsightedness, is an eye defect caused by the inability of the eye to focus light directly on the retina. In myopia:

The eyeball is too long, or the cornea is too curved.
Light focuses in front of the retina, causing distant objects to appear blurry.
Close objects can be seen clearly.

Why not the others?

(A) Glaucoma: This is caused by increased pressure in the eye, damaging the optic nerve, not by focusing issues.
(C) Cataracts: This is caused by the clouding of the lens, leading to blurred vision, but it is not due to improper focusing of light on the retina.
(D) Astigmatism: This is caused by an irregularly shaped cornea or lens, leading to distorted vision, but it is not specifically about focusing light on the retina.

Thus, myopia is the eye defect caused by the inability to focus light on the retina.

60. Germination is the process in which a seed

A. Begins to photosynthesize
B. Develops into a mature plant
C. Absorbs nutrients from the soil
D. Breaks dormancy and starts to grow

The correct answer is (D) Breaks dormancy and starts to grow.

Explanation:

Germination is the process by which a seed breaks dormancy and begins to grow into a new plant. It involves several stages:

Imbibition: The seed absorbs water, swelling and breaking the seed coat.
Activation of metabolism: Enzymes are activated, and stored nutrients are broken down to provide energy.
Emergence of the radicle: The first root (radicle) emerges, followed by the shoot.

Germination requires favorable conditions, such as water, oxygen, and appropriate temperature.

Why not the others?

(A) Begins to photosynthesize: Photosynthesis begins after the seedling develops leaves, not during germination.
(B) Develops into a mature plant: Germination is the initial stage of growth, not the entire process of becoming a mature plant.
(C) Absorbs nutrients from the soil: While the seedling eventually absorbs nutrients from the soil, this occurs after germination, not during the initial process.

Thus, germination is the process in which a seed breaks dormancy and starts to grow.

61. Which of the following statements is true regarding sexual reproduction in organisms?

A. It involves the fusion of gametes from two parents, resulting in offspring with genetic variation
B. It involves the production of offspring through a single parent, resulting in genetically identical offspring
C. It is a form of asexual reproduction where offspring are produced without the involvement of gametes
D. It does not involve the formation of gametes or the fusion of reproductive cells

The correct answer is (A) It involves the fusion of gametes from two parents, resulting in offspring with genetic variation.

Explanation:

Sexual reproduction involves the fusion of gametes (sperm and egg) from two parents, resulting in offspring with genetic variation. Key features include:

Formation of gametes through meiosis.
Fertilization, where gametes fuse to form a zygote.
Offspring inherit a unique combination of genes from both parents, leading to diversity.

Why not the others?

(B) It involves the production of offspring through a single parent, resulting in genetically identical offspring: This describes asexual reproduction, not sexual reproduction.
(C) It is a form of asexual reproduction where offspring are produced without the involvement of gametes: This is incorrect, as sexual reproduction specifically involves gametes.
(D) It does not involve the formation of gametes or the fusion of reproductive cells: This is incorrect, as sexual reproduction requires gametes and their fusion.

Thus, sexual reproduction involves the fusion of gametes from two parents, resulting in offspring with genetic variation.

62. Which of the following is a method of asexual reproduction in plants?

A. Pollination
B. Vegetative propagation
C. Seed dispersal
D. Fertilization

The correct answer is (B) Vegetative propagation.

Explanation:

Vegetative propagation is a method of asexual reproduction in plants where new plants grow from vegetative parts such as roots, stems, or leaves, rather than from seeds. Examples include:

Runners (e.g., strawberries).
Tubers (e.g., potatoes).
Bulbs (e.g., onions).
Cuttings (e.g., rose plants).

This method produces genetically identical offspring (clones) of the parent plant.

Why not the others?

(A) Pollination: This is part of sexual reproduction, involving the transfer of pollen from the male part of a flower to the female part.
(C) Seed dispersal: This is a mechanism for spreading seeds, which are products of sexual reproduction.
(D) Fertilization: This is the fusion of male and female gametes, a key step in sexual reproduction.

Thus, vegetative propagation is a method of asexual reproduction in plants.

63. Which of the following plant tissues is responsible for transporting water and nutrients from the roots to the rest of the plant?

A. Mesophyll
B. Xylem
C. Epidermis
D. Phloem

The correct answer is (B) Xylem.

Explanation:

The xylem is a specialized plant tissue responsible for transporting water and nutrients from the roots to the rest of the plant. Key features of the xylem include:

It consists of hollow, tube-like structures made of dead cells.
It transports water and dissolved minerals upward through the plant.
It also provides structural support to the plant.

Why not the others?

(A) Mesophyll: This is the tissue in leaves where photosynthesis occurs, not involved in water and nutrient transport.
(C) Epidermis: This is the outer protective layer of the plant, not involved in transport.
(D) Phloem: This tissue transports sugars and other organic nutrients (e.g., amino acids) from the leaves to other parts of the plant, not water and minerals.

Thus, the xylem is responsible for transporting water and nutrients from the roots to the rest of the plant.

64. Which of the following statements best describes courtship behaviors in animals?

A. Courtship behaviors are solely performed by males to establish dominance within a social group
B. Courtship behaviors involve displays and rituals performed by both males and females to attract a mate
C. Courtship behaviors are primarily performed by females to attract males for mating
D. Courtship behaviors are aggressive interactions between males competing for a female mate

The correct answer is (B) Courtship behaviors involve displays and rituals performed by both males and females to attract a mate.

Explanation:

Courtship behaviors are a series of displays and rituals performed by animals to attract a mate and ensure successful reproduction. These behaviors can include:

Visual displays (e.g., peacock feathers).
Vocalizations (e.g., bird songs).
Dances or movements (e.g., mating dances in birds or fish).
Gift-giving (e.g., presenting food or nesting materials).

Courtship behaviors are often performed by both males and females, though the specific roles can vary between species.

Why not the others?

(A) Courtship behaviors are solely performed by males to establish dominance within a social group: This is incorrect, as courtship behaviors are about attracting mates, not establishing dominance.
(C) Courtship behaviors are primarily performed by females to attract males for mating: This is incorrect, as courtship behaviors are often performed by males, though both sexes can participate.
(D) Courtship behaviors are aggressive interactions between males competing for a female mate: This describes male-male competition, not courtship behaviors.

Thus, courtship behaviors involve displays and rituals performed by both males and females to attract a mate.

65. Which of the following best describes physiological variation in biology?

A. Variations in the physiological processes and functions of organisms
B. Differences in physical characteristics and appearance within a population
C. Differences in behavior and social interactions among individuals
D. Variations in the genetic makeup of individuals within a species

The correct answer is (A) Variations in the physiological processes and functions of organisms.

Explanation:

Physiological variation refers to differences in the internal functions and processes of organisms, such as:

Metabolic rate.
Enzyme activity.
Hormone levels.
Blood pressure.
Immune response.

These variations can be influenced by genetics, environment, or health status.

Why not the others?

(B) Differences in physical characteristics and appearance within a population: This describes morphological variation, not physiological variation.
(C) Differences in behavior and social interactions among individuals: This describes behavioral variation, not physiological variation.
(D) Variations in the genetic makeup of individuals within a species: This describes genetic variation, which can influence physiological variation but is not the same thing.

Thus, physiological variation refers to variations in the physiological processes and functions of organisms.

66. Which of the following options correctly identifies excretory organs in animals?

A. Stomach, intestines, and bladder
B. Lungs, kidneys, and skin
C. Brain, spinal cord, and nerves
D. Heart, liver, and spleen

The correct answer is (B) Lungs, kidneys, and skin.

Explanation:

Excretory organs are responsible for removing waste products from the body. The primary excretory organs in animals include:

Lungs: Excrete carbon dioxide (a waste product of respiration).
Kidneys: Filter blood to remove urea, excess water, and toxins, producing urine.
Skin: Excretes water, salts, and small amounts of urea through sweat.

Why not the others?

(A) Stomach, intestines, and bladder: The stomach and intestines are part of the digestive system, and the bladder stores urine but does not excrete waste.
(C) Brain, spinal cord, and nerves: These are part of the nervous system and are not involved in excretion.
(D) Heart, liver, and spleen: The heart pumps blood, the liver detoxifies chemicals, and the spleen filters blood, but none are primary excretory organs.

Thus, the correct excretory organs are the lungs, kidneys, and skin.

67. Which of the following best describes the concept of trophic levels in a functioning ecosystem?

A. The levels of ecological interactions within an ecosystem
B. The levels of energy flow within an ecosystem
C. The levels of nutrient cycling within an ecosystem
D. The levels of biological diversity within an ecosystem

The correct answer is (B) The levels of energy flow within an ecosystem.

Explanation:

Trophic levels represent the levels of energy flow within an ecosystem, describing the position of organisms in a food chain or web. Each level represents a step in the transfer of energy, starting from producers to consumers. The main trophic levels are:

Producers (e.g., plants): Convert sunlight into energy through photosynthesis.
Primary consumers (e.g., herbivores): Feed on producers.
Secondary consumers (e.g., carnivores): Feed on primary consumers.
Tertiary consumers (e.g., top predators): Feed on secondary consumers.
Decomposers: Break down dead organisms and recycle nutrients.

Why not the others?

(A) The levels of ecological interactions within an ecosystem: This is too broad and does not specifically describe energy flow.
(C) The levels of nutrient cycling within an ecosystem: Nutrient cycling involves the movement of elements like carbon and nitrogen, not energy flow.
(D) The levels of biological diversity within an ecosystem: This refers to the variety of species, not energy flow.

Thus, trophic levels describe the levels of energy flow within an ecosystem.

68. Which of the following statements best describes pollination in plants?

A. Pollination is the process of transferring pollen from the stigma to the anther of a flower
B. Pollination is the process of transferring pollen from the anther to the stigma of a flower
C. Pollination is the process of releasing pollen into the air for dispersal
D. Pollination is the process of seed formation within a flower

The correct answer is (B) Pollination is the process of transferring pollen from the anther to the stigma of a flower.

Explanation:

Pollination is the process by which pollen is transferred from the anther (male part of the flower) to the stigma (female part of the flower). This transfer can occur through:

Wind (e.g., grasses).
Animals (e.g., bees, butterflies).
Water (e.g., aquatic plants).

Pollination is a crucial step in the sexual reproduction of flowering plants, leading to fertilization and seed formation.

Why not the others?

(A) Pollination is the process of transferring pollen from the stigma to the anther of a flower: This is incorrect, as pollen moves from the anther to the stigma, not the reverse.
(C) Pollination is the process of releasing pollen into the air for dispersal: This describes pollen dispersal, not pollination.
(D) Pollination is the process of seed formation within a flower: Seed formation occurs after pollination and fertilization, not during pollination.

Thus, pollination is the process of transferring pollen from the anther to the stigma of a flower.

69. Which of the following best describes a natural habitat in ecology?

A. An area where organisms naturally live and interact with their surroundings
B. A human-created environment for wildlife conservation
C. A controlled laboratory setting for ecological experiments
D. A protected area for endangered species

The correct answer is (A) An area where organisms naturally live and interact with their surroundings.

Explanation:

A natural habitat is the natural environment where an organism or community of organisms lives and interacts with its surroundings. It includes all the biotic (living) and abiotic (non-living) factors that influence the organism’s survival, such as:

Climate.
Soil.
Water.
Other species.

Examples include forests, deserts, oceans, and grasslands.

Why not the others?

(B) A human-created environment for wildlife conservation: This describes a sanctuary or reserve, not a natural habitat.
(C) A controlled laboratory setting for ecological experiments: This is an artificial environment, not a natural habitat.
(D) A protected area for endangered species: This describes a conservation area, not necessarily a natural habitat.

Thus, a natural habitat is an area where organisms naturally live and interact with their surroundings.

70. Which of the following statements about viruses is true?

A. Viruses can reproduce outside of a host cell
B. Viruses require a host cell to replicate
C. Viruses possess a cellular structure
D. Viruses are living organisms

The correct answer is (B) Viruses require a host cell to replicate.

Explanation:

Viruses are unique entities that require a host cell to replicate. They cannot reproduce on their own because they lack the cellular machinery needed for metabolism and replication. Instead, they infect host cells and hijack their machinery to produce new virus particles. Key features of viruses include:

They consist of genetic material (DNA or RNA) surrounded by a protein coat (capsid).
They are not considered living organisms because they cannot carry out life processes independently.

Why not the others?

(A) Viruses can reproduce outside of a host cell: This is incorrect, as viruses cannot replicate without a host cell.
(C) Viruses possess a cellular structure: This is incorrect, as viruses are acellular and do not have a cellular structure.
(D) Viruses are living organisms: This is incorrect, as viruses are not considered living because they cannot carry out life processes independently.

Thus, the true statement is that viruses require a host cell to replicate.

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1. Which of the following is an example of a microorganism in action as a disease vector?

Explanation:

Why not the others?

2. Which of the following is a characteristic of cells related to irritability?

Explanation:

Why not the others?

3. The membrane around the vacuole is known as

Explanation:

Why not the others?

4. Which of the following is evidence of evolution?

Explanation:

Why is (A) correct?

5. Which of the following is an example of an adaptation for survival in social insects?

Explanation:

Why not the others?

6. Which of the following is NOT a part of the alimentary canal?

Explanation:

Why not the others?

7. Which of the following is an evolutionary trend commonly observed in organisms?

Explanation:

Why not the others?

8. Which of the following is a characteristic feature of Kingdom Plantae?

Explanation:

Why not the others?

9. A biome characterized by hot summer, warm winter and treeless vegetation is

Explanation:

Why not the others?

10. Which of the following is an example of physiological variation in organisms?

Explanation:

Why not the others?

11. Which of the following are components of the skeletal system in humans?

Explanation:

Why not the others?

12. Which of the following represents an example of ecological management and conservation through a biological association?

Explanation:

Why not the others?

13. The term cell was given by

Explanation:

Why not the others?

14. Which of the following is the primary organ involved in gas exchange during respiration in humans?

Explanation:

Why not the others?

15. Which gland is responsible for producing the hormone insulin?

Explanation:

Why not the others?

16. Most fishes do not sink in water because of the presences of:I. swim bladderII. air bladderIII. air sacsIV. air in spongy bones

Explanation:

Why not the others?

17. In monohybrid inheritance, if an organism carries two different alleles for a particular gene, it is called:

Explanation:

Why not the others?

18. What is the tissue responsible for transporting water and minerals from the roots to the rest of the plant?

Explanation:

Why not the others?

19. Which of the following is an example of an abiotic ecological factor?

Explanation:

Why not the others?

20. Which of the following processes is involved in the reproduction of developing organisms?

Explanation:

Why not the others?

21. Behavioral adaptation for dealing with a hot climate could include

Explanation:

Why not the others?

22. The natural place of an organism or community is known as

Explanation:

Why not the others?

23. Which process in the nutrient cycle converts atmospheric nitrogen into a form that plants can utilize?

Explanation:

Why not the others?

24. Which of the following functions is performed by the skin to help maintain homeostasis in the human body?

Explanation:

Why not the others?

25. Which of the following soil types becomes less fertile due to the intense leaching caused by tropical rains?

Explanation:

Why not the others?

26. Which type of reproduction involves the fusion of gametes from two parents?

Explanation:

Why not the others?

27. Which processes are involved in nutrient cycling in a functioning ecosystem?

Explanation:

16. Most fishes do not sink in water because of the presences of:
I. swim bladder
II. air bladder
III. air sacs
IV. air in spongy bones