Biology MCQs

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Biology MCQs

Practice complete Biology MCQs covering Introduction to Biology, Cell Biology, Cell Structure, Cell Division, Biomolecules, Plant Physiology, Human Physiology, Genetics, Evolution, Biotechnology, Ecology, Classification of Living Organisms, Plant Kingdom, Animal Kingdom, Microbiology, Human Diseases, Nutrition, Reproduction, Environmental Biology, and all other important topics. Includes chapter-wise and exam-oriented multiple-choice questions with detailed answers and explanations for JKSSB, SSC, Banking, Railway, UPSC, CUET, NEET, State PSCs, and other competitive exams.

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Page 96 of 103
Question #1901
Consider statements about biotechnology: 1. Genetic engineering can create transgenic organisms. 2. Cloning produces genetically identical copies. 3. Tissue culture is used for animal cloning only. Which are correct?
A. 2 and 3 only
B. 1 and 3 only
C. 1 and 2 only
D. 1, 2 and 3
Discuss
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Correct Answer: Option C

Explanation:
Genetic engineering involves the direct manipulation of an organism's genome, often used to create transgenic organisms that contain foreign DNA (transgenes) for desired traits. Cloning is the process of producing genetically identical copies of a biological entity, ranging from genes to entire organisms. Tissue culture (micropropagation) is widely used for the rapid, large-scale propagation of plants from small explants in a sterile medium; it is not exclusively or primarily used for animal cloning. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1902
Consider statements about animal husbandry: 1. Dairy farming involves milk production. 2. Poultry farming involves meat and egg production. 3. Apiculture involves silk production. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 3 only
D. 1 and 2 only
Discuss
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Correct Answer: Option D

Explanation:
Dairy farming is the agricultural practice of breeding and raising livestock (like cows, buffaloes, goats) specifically for the long-term production of milk and milk products. Poultry farming involves the commercial rearing of domesticated birds (like chickens, ducks, turkeys) for the production of meat (broilers) and eggs (layers). Apiculture is the scientific rearing and management of honeybees (Apis species) for the production of honey, beeswax, and other hive products; silk production is sericulture. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1903
Consider statements about scientists: 1. Robert Hooke coined the term 'cell'. 2. Antonie van Leeuwenhoek discovered living microorganisms. 3. Charles Darwin proposed the cell theory. Which are correct?
A. 1 and 3 only
B. 1 and 2 only
C. 1, 2 and 3
D. 2 and 3 only
Discuss
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Correct Answer: Option B

Explanation:
Robert Hooke, in his 1665 book 'Micrographia', described observing dead cork tissue under a microscope and coined the term 'cell' for the small, box-like compartments he saw. Antonie van Leeuwenhoek, using his superior handcrafted single-lens microscopes in the 1670s, was the first person to observe and describe living, single-celled microorganisms, which he called 'animalcules'. Charles Darwin proposed the theory of evolution by natural selection; the cell theory was proposed by Schleiden and Schwann. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1904
Consider statements about cell biology: 1. The plasma membrane regulates transport. 2. The nucleus contains DNA. 3. Mitochondria produce ATP. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 3 only
D. 1 and 2 only
Discuss
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Correct Answer: Option B

Explanation:
The plasma membrane (cell membrane) is selectively permeable, regulating the entry and exit of substances into and out of the cell, maintaining internal homeostasis. The nucleus is the membrane-bound organelle that houses the cell's genetic material (DNA) organized into chromosomes, directing cellular activities. Mitochondria are the double-membrane-bound organelles known as the 'powerhouses of the cell' because they are the primary site of aerobic respiration, producing the majority of the cell's ATP (energy currency). All statements are correct.
This question belongs to: Science Biology
Question #1905
Consider statements about plant biology: 1. Xylem transports water upwards. 2. Phloem transports food bidirectionally. 3. Cambium is responsible for secondary growth. Which are correct?
A. 2 and 3 only
B. 1 and 2 only
C. 1 and 3 only
D. 1, 2 and 3
Discuss
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Correct Answer: Option D

Explanation:
Xylem is the vascular tissue responsible for the unidirectional upward transport of water and dissolved minerals from the roots to the aerial parts of the plant. Phloem is the vascular tissue responsible for the translocation of organic nutrients (primarily sucrose) from sources to sinks, which can be bidirectional (up or down depending on the plant's needs). Cambium (vascular and cork) is a lateral meristem responsible for secondary growth, which is the increase in the girth or thickness of stems and roots. All statements are correct.
This question belongs to: Science Biology
Question #1906
Consider statements about human anatomy: 1. The brain is the control center of the nervous system. 2. The heart is the pump of the circulatory system. 3. The lungs are the organs of the respiratory system. Which are correct?
A. 1, 2 and 3
B. 2 and 3 only
C. 1 and 2 only
D. 1 and 3 only
Discuss
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Correct Answer: Option A

Explanation:
The brain is the central and most complex organ of the nervous system, processing sensory information, controlling motor functions, and regulating higher cognitive processes. The heart is a muscular organ that acts as the central pump of the circulatory system, propelling blood through the network of blood vessels to deliver oxygen and nutrients. The lungs are a pair of spongy, air-filled organs that are the primary components of the respiratory system, facilitating the vital exchange of oxygen and carbon dioxide. All statements are correct.
This question belongs to: Science Biology
Question #1907
Consider statements about human physiology: 1. The stomach secretes acid for digestion. 2. The small intestine is the main site of absorption. 3. The liver produces bile. Which are correct?
A. 1 and 3 only
B. 1 and 2 only
C. 1, 2 and 3
D. 2 and 3 only
Discuss
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Correct Answer: Option C

Explanation:
The stomach's gastric glands secrete hydrochloric acid (HCl), which creates an acidic environment necessary for the activation of pepsin and the initial digestion of proteins. The small intestine, with its vast surface area provided by villi and microvilli, is the primary site for the final digestion and absorption of most nutrients into the bloodstream. The liver is a large, multifunctional organ that continuously produces bile, which is stored in the gall bladder and released into the small intestine to emulsify fats. All statements are correct.
This question belongs to: Science Biology
Question #1908
Consider statements about human diseases: 1. Cholera is caused by a bacterium. 2. Polio is caused by a virus. 3. Ringworm is caused by a fungus. Which are correct?
A. 1, 2 and 3
B. 2 and 3 only
C. 1 and 3 only
D. 1 and 2 only
Discuss
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Correct Answer: Option A

Explanation:
Cholera is an acute diarrheal disease caused by the bacterium Vibrio cholerae, typically transmitted through contaminated water and food. Polio (poliomyelitis) is a highly infectious viral disease caused by the poliovirus, which can invade the nervous system and cause paralysis. Ringworm (dermatophytosis) is a common superficial fungal infection of the skin, hair, or nails caused by dermatophytes like Microsporum, Trichophyton, and Epidermophyton. All three statements correctly identify the causative agents.
This question belongs to: Science Biology
Question #1909
Consider statements about human immunity: 1. Skin is a physical barrier. 2. White blood cells fight infection. 3. Antibiotics kill viruses. Which are correct?
A. 1, 2 and 3
B. 2 and 3 only
C. 1 and 3 only
D. 1 and 2 only
Discuss
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Correct Answer: Option D

Explanation:
The skin and mucous membranes form the first line of defense (innate immunity), acting as physical barriers that prevent pathogens from entering the body. White blood cells (leukocytes), including phagocytes and lymphocytes, are the cellular components of the immune system that identify, attack, and destroy pathogens. Antibiotics are drugs specifically designed to kill or inhibit the growth of bacteria by targeting their unique structures or metabolic pathways; they are completely ineffective against viruses. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1910
Consider statements about human nutrition: 1. Carbohydrates provide energy. 2. Proteins build and repair tissues. 3. Fats are harmful and should be avoided. Which are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3
Discuss
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Correct Answer: Option A

Explanation:
Carbohydrates are the body's primary and most efficient source of energy, broken down into glucose to fuel cellular activities and physical exertion. Proteins are essential macronutrients composed of amino acids, crucial for the growth, maintenance, and repair of body tissues, as well as forming enzymes, hormones, and antibodies. Fats are essential macronutrients; they provide concentrated energy, are vital for cell membrane structure, aid in the absorption of fat-soluble vitamins, and provide essential fatty acids. They should not be entirely avoided. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1911
Consider statements about vitamins: 1. Vitamin A deficiency causes night blindness. 2. Vitamin B1 deficiency causes beriberi. 3. Vitamin C deficiency causes scurvy. Which are correct?
A. 1 and 3 only
B. 1, 2 and 3
C. 1 and 2 only
D. 2 and 3 only
Discuss
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Correct Answer: Option B

Explanation:
Vitamin A is essential for the synthesis of rhodopsin, a visual pigment; its deficiency leads to night blindness, the inability to see in low light conditions. Vitamin B1 (thiamine) is crucial for carbohydrate metabolism; its deficiency causes beriberi, characterized by nerve and heart dysfunction, and muscle weakness. Vitamin C (ascorbic acid) is essential for collagen synthesis; its deficiency causes scurvy, characterized by bleeding gums, loose teeth, and poor wound healing. All three statements are correct.
This question belongs to: Science Biology
Question #1912
Consider statements about genetics: 1. Genes are made of DNA. 2. Chromosomes are located in the nucleus. 3. RNA is the genetic material in all cells. Which are correct?
A. 2 and 3 only
B. 1 and 2 only
C. 1 and 3 only
D. 1, 2 and 3
Discuss
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Correct Answer: Option B

Explanation:
Genes are specific sequences of nucleotides that serve as the fundamental units of heredity, and in all cellular organisms, they are made of DNA (deoxyribonucleic acid). Chromosomes are thread-like structures composed of DNA and proteins, and they are located within the nucleus of eukaryotic cells. DNA is the genetic material in all cellular organisms; RNA serves as the genetic material only in some viruses, not in cells. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1913
Consider statements about evolution: 1. Natural selection was proposed by Darwin. 2. Mutation theory was proposed by de Vries. 3. Use and disuse theory was proposed by Lamarck. Which are correct?
A. 1 and 2 only
B. 1, 2 and 3
C. 1 and 3 only
D. 2 and 3 only
Discuss
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Correct Answer: Option B

Explanation:
Charles Darwin proposed the theory of evolution by natural selection, emphasizing that organisms with favorable variations are more likely to survive and reproduce. Hugo de Vries, a Dutch botanist, proposed the mutation theory of evolution based on his work on evening primrose, stating that evolution occurs through sudden, large mutations (saltations). Jean-Baptiste Lamarck proposed the theory of inheritance of acquired characters, based on the use and disuse of organs (e.g., giraffe's neck). All statements are correct.
This question belongs to: Science Biology
Question #1914
Consider statements about ecology: 1. A population consists of individuals of the same species. 2. A community consists of interacting populations. 3. An ecosystem consists of biotic and abiotic components. Which are correct?
A. 1, 2 and 3
B. 1 and 2 only
C. 1 and 3 only
D. 2 and 3 only
Discuss
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Correct Answer: Option A

Explanation:
A population is a group of individuals of the same species living in a specific geographic area and capable of interbreeding. A community comprises all the interacting populations of different species (plants, animals, microbes) living together in a defined area. An ecosystem is a functional unit of nature that encompasses both the biotic (living community) and abiotic (non-living physical environment like soil, water, sunlight) components, interacting as a complex system. All statements are correct.
This question belongs to: Science Biology
Question #1915
Consider statements about environment: 1. Deforestation causes soil erosion. 2. Afforestation helps reduce global warming. 3. Plastic is non-biodegradable. Which are correct?
A. 1, 2 and 3
B. 2 and 3 only
C. 1 and 2 only
D. 1 and 3 only
Discuss
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Correct Answer: Option A

Explanation:
Deforestation, the large-scale removal of trees and vegetation, exposes the topsoil to wind and water, leading to severe soil erosion and loss of fertility. Afforestation, the planting of trees in barren areas, increases biomass and helps mitigate global warming by sequestering atmospheric carbon dioxide through photosynthesis. Most plastics are synthetic polymers that are non-biodegradable, meaning they cannot be broken down by natural biological processes and persist in the environment for centuries, causing pollution. All statements are correct.
This question belongs to: Science Biology
Question #1916
Consider statements about microorganisms: 1. Bacteria are prokaryotes. 2. Fungi are eukaryotes. 3. Viruses have a cellular structure. Which are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3
Discuss
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Correct Answer: Option A

Explanation:
Bacteria are unicellular prokaryotic organisms, characterized by the absence of a true, membrane-bound nucleus and other membrane-bound organelles. Fungi are eukaryotic organisms, possessing a true nucleus and membrane-bound organelles, and can be unicellular (yeasts) or multicellular (molds, mushrooms). Viruses are acellular, non-cellular entities; they consist of genetic material (DNA or RNA) enclosed in a protein coat (capsid) and lack any cellular structure or independent metabolic machinery. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1917
Consider statements about biotechnology: 1. PCR amplifies DNA. 2. Gel electrophoresis separates DNA by size. 3. Restriction enzymes join DNA fragments. Which are correct?
A. 2 and 3 only
B. 1 and 2 only
C. 1 and 3 only
D. 1, 2 and 3
Discuss
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Correct Answer: Option B

Explanation:
Polymerase Chain Reaction (PCR) is a powerful molecular technique used to exponentially amplify a specific segment of DNA, creating millions of copies from a small initial sample. Gel electrophoresis is a laboratory method used to separate DNA, RNA, or protein molecules based on their size and charge by applying an electric field through a gel matrix. Restriction enzymes are molecular scissors that cut DNA at specific sequences; DNA ligase is the enzyme that joins DNA fragments together. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1918
Consider statements about animal husbandry: 1. Dairy farming produces milk. 2. Poultry farming produces meat and eggs. 3. Apiculture produces silk. Which are correct?
A. 1 and 3 only
B. 1 and 2 only
C. 1, 2 and 3
D. 2 and 3 only
Discuss
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Correct Answer: Option B

Explanation:
Dairy farming is the agricultural practice of breeding and raising livestock (like cows, buffaloes, goats) specifically for the long-term production of milk and dairy products. Poultry farming involves the commercial rearing of domesticated birds (like chickens, ducks, turkeys) for the production of meat (broilers) and eggs (layers). Apiculture is the scientific rearing and management of honeybees (Apis species) for the production of honey, beeswax, and other hive products; silk production is the domain of sericulture. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1919
Consider statements about cell biology: 1. The cell membrane is selectively permeable. 2. The nucleus contains genetic material. 3. Mitochondria are the site of photosynthesis. Which are correct?
A. 1, 2 and 3
B. 1 and 3 only
C. 2 and 3 only
D. 1 and 2 only
Discuss
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Correct Answer: Option D

Explanation:
The cell membrane (plasma membrane) is selectively permeable, regulating the passage of substances in and out of the cell to maintain internal homeostasis. The nucleus is the membrane-bound organelle that houses the cell's genetic material (DNA) organized into chromosomes, directing cellular activities. Mitochondria are the site of aerobic cellular respiration and ATP production; chloroplasts are the organelles where photosynthesis occurs in plant cells. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1920
Consider statements about plant biology: 1. Xylem transports water. 2. Phloem transports food. 3. Cambium is responsible for primary growth. Which are correct?
A. 1 and 3 only
B. 1, 2 and 3
C. 1 and 2 only
D. 2 and 3 only
Discuss
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Correct Answer: Option C

Explanation:
Xylem is the vascular tissue responsible for the unidirectional upward transport of water and dissolved minerals from the roots to the aerial parts of the plant. Phloem is the vascular tissue responsible for the translocation of organic nutrients (primarily sucrose) from sources to sinks, which can be bidirectional. Cambium (vascular and cork) is a lateral meristem responsible for secondary growth (increase in girth); primary growth (increase in length) is driven by apical meristems. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology

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