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 93 of 103
Question #1841
Consider statements about cell biology: 1. The cell membrane is selectively permeable. 2. The cell wall is present in all plant cells. 3. The nucleus is the control center of the cell. 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 cell membrane (plasma membrane) is selectively permeable, regulating the passage of substances in and out of the cell. The cell wall is a rigid, non-living outer layer present in all plant cells, providing structural support and shape. The nucleus is the control center of the eukaryotic cell, housing the genetic material (DNA) and directing cellular activities like growth, metabolism, and reproduction. All three statements are correct.
This question belongs to: Science Biology
Question #1842
Consider statements about plant biology: 1. Photosynthesis occurs in chloroplasts. 2. Respiration occurs in mitochondria. 3. Transpiration occurs through lenticels. 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:
Photosynthesis, the process of converting light energy into chemical energy, occurs in the chloroplasts, specifically involving the thylakoid membranes and stroma. Cellular respiration, the process of breaking down glucose to release ATP, occurs primarily in the mitochondria. Transpiration is the loss of water vapor from plants, and while it can occur through lenticels (lenticular transpiration) and the cuticle, the vast majority (about 90%) occurs through the stomata (stomatal transpiration). Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1843
Consider statements about human anatomy: 1. The brain is part of the central nervous system. 2. The spinal cord is part of the peripheral nervous system. 3. Nerves are part of the peripheral nervous system. Which are correct?
A. 1 and 3 only
B. 2 and 3 only
C. 1 and 2 only
D. 1, 2 and 3
Discuss
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Correct Answer: Option A

Explanation:
The nervous system is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain and the spinal cord, which process and coordinate information. The PNS consists of all the neural structures outside the CNS, including cranial nerves, spinal nerves, and ganglia, which connect the CNS to the rest of the body. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1844
Consider statements about human physiology: 1. The kidney filters blood to form urine. 2. The liver produces bile for fat digestion. 3. The spleen produces digestive enzymes. Which are correct?
A. 1, 2 and 3
B. 1 and 2 only
C. 2 and 3 only
D. 1 and 3 only
Discuss
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Correct Answer: Option B

Explanation:
The kidneys are the primary excretory organs, filtering blood through nephrons to remove waste products and excess water, forming urine. The liver is a multifunctional organ that produces bile, which is stored in the gall bladder and released into the small intestine to emulsify fats, aiding in their digestion. The spleen is a lymphoid organ involved in filtering blood and immune responses; it does not produce digestive enzymes (the pancreas does). Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1845
Consider statements about human diseases: 1. HIV attacks the immune system. 2. Malaria is caused by a virus. 3. Tuberculosis affects the lungs. 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 B

Explanation:
Human Immunodeficiency Virus (HIV) specifically targets and destroys CD4+ T-helper cells, severely compromising the immune system and leading to AIDS. Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis, which primarily affects the lungs (pulmonary TB). Malaria is not caused by a virus; it is caused by a protozoan parasite of the genus Plasmodium, transmitted by the Anopheles mosquito. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1846
Consider statements about human nutrition: 1. Carbohydrates provide immediate energy. 2. Proteins are body-building foods. 3. Fats are not essential for the body. Which are correct?
A. 1 and 3 only
B. 2 and 3 only
C. 1, 2 and 3
D. 1 and 2 only
Discuss
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Correct Answer: Option D

Explanation:
Carbohydrates are the body's primary and most readily available source of energy, broken down into glucose for immediate cellular use. Proteins are essential 'body-building' foods, providing amino acids necessary for the growth, repair, and maintenance of tissues, muscles, and enzymes. Fats are essential macronutrients; they provide concentrated energy, are crucial for cell membrane structure, aid in the absorption of fat-soluble vitamins, and provide essential fatty acids. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1847
Consider statements about vitamins: 1. Vitamin A is essential for good vision. 2. Vitamin C prevents scurvy. 3. Vitamin D is essential for blood clotting. Which are correct?
A. 1 and 3 only
B. 1 and 2 only
C. 2 and 3 only
D. 1, 2 and 3
Discuss
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Correct Answer: Option B

Explanation:
Vitamin A (retinol) is crucial for the maintenance of the cornea and the synthesis of rhodopsin, a pigment necessary for vision in dim light. Vitamin C (ascorbic acid) is essential for the synthesis of collagen; its deficiency leads to scurvy, characterized by bleeding gums and poor wound healing. Vitamin K, not Vitamin D, is essential for the synthesis of prothrombin and other clotting factors. Vitamin D is essential for calcium absorption and bone health. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1848
Consider statements about genetics: 1. DNA contains the sugar deoxyribose. 2. RNA contains the sugar ribose. 3. DNA is single-stranded. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 2 only
D. 1 and 3 only
Discuss
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Correct Answer: Option C

Explanation:
DNA (deoxyribonucleic acid) is characterized by the presence of the pentose sugar deoxyribose in its nucleotide backbone. RNA (ribonucleic acid) contains the pentose sugar ribose. DNA is typically a double-stranded helical molecule, providing stability for long-term genetic storage. RNA is generally single-stranded, allowing it to fold into complex shapes and perform various functional roles like mRNA, tRNA, and rRNA. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1849
Consider statements about evolution: 1. Variation is necessary for evolution. 2. Natural selection acts on phenotype. 3. Evolution occurs in individuals. 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:
Genetic variation within a population provides the raw material upon which evolutionary forces act; without variation, evolution cannot occur. Natural selection acts directly on the phenotype (observable traits) of an organism, determining its survival and reproductive success. However, evolution is a population-level phenomenon; it involves changes in allele frequencies over generations, not changes occurring within a single individual's lifetime. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1850
Consider statements about ecology: 1. An ecosystem includes living and non-living components. 2. A community includes only one species. 3. A population includes individuals of the same species. Which are correct?
A. 1, 2 and 3
B. 1 and 3 only
C. 1 and 2 only
D. 2 and 3 only
Discuss
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Correct Answer: Option B

Explanation:
An ecosystem is a functional unit comprising both the biotic (living organisms) and abiotic (non-living physical environment like soil, water, sunlight) components interacting as a system. A population is a group of individuals of the same species living in a specific area and interbreeding. A community consists of all the interacting populations of different species living together in a defined area, not just one species. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1851
Consider statements about environment: 1. Acid rain damages buildings and monuments. 2. Ozone depletion increases UV radiation. 3. Global warming is caused by a decrease in greenhouse gases. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 2 only
D. 1 and 3 only
Discuss
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Correct Answer: Option C

Explanation:
Acid rain, containing sulfuric and nitric acids, corrodes buildings, monuments (like the Taj Mahal), and statues made of limestone and marble. The depletion of the stratospheric ozone layer reduces its ability to absorb harmful ultraviolet (UV-B) radiation, increasing the amount reaching the Earth's surface. Global warming is caused by an increase, not a decrease, in atmospheric greenhouse gases (like CO2 and methane), which trap more heat. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1852
Consider statements about microorganisms: 1. Bacteria can be autotrophic or heterotrophic. 2. Viruses are considered living outside a host. 3. Fungi are eukaryotic organisms. 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 C

Explanation:
Bacteria exhibit diverse nutritional modes; some are autotrophic (photosynthetic like cyanobacteria or chemosynthetic), while others are heterotrophic (saprophytic or parasitic). Fungi are eukaryotic organisms, characterized by having a true nucleus and membrane-bound organelles, and are heterotrophic. Viruses are considered non-living outside a host cell because they lack metabolic machinery and cannot replicate independently; they only exhibit living characteristics inside a host. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1853
Consider statements about biotechnology: 1. Transgenic organisms contain foreign DNA. 2. Cloning produces genetically identical copies. 3. Gene therapy cures all genetic diseases. Which are correct?
A. 1, 2 and 3
B. 1 and 2 only
C. 2 and 3 only
D. 1 and 3 only
Discuss
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Correct Answer: Option B

Explanation:
Transgenic organisms (plants or animals) have been genetically modified to contain and express foreign DNA (a transgene) from another species. Cloning is a technique used to produce genetically identical copies of a biological entity, such as a cell, organism, or DNA sequence. Gene therapy is an emerging technique aimed at treating or curing genetic diseases by introducing functional genes, but it is still largely experimental and does not currently cure all genetic diseases. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1854
Consider statements about animal husbandry: 1. Dairy farming involves the rearing of milk-producing animals. 2. Poultry farming involves the rearing of birds for meat and eggs. 3. Apiculture involves the rearing of silkworms. Which are correct?
A. 1 and 3 only
B. 2 and 3 only
C. 1, 2 and 3
D. 1 and 2 only
Discuss
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Correct Answer: Option D

Explanation:
Dairy farming is the business of breeding, raising, and managing dairy animals (like cows and buffaloes) for the production of milk and milk products. Poultry farming involves the commercial raising of domesticated birds (like chickens, ducks, and turkeys) for the production of meat and eggs. Apiculture is the scientific rearing of honeybees (Apis species) for the production of honey, beeswax, and other hive products; silkworm rearing is sericulture. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1855
Consider statements about scientists: 1. Carolus Linnaeus is the father of taxonomy. 2. Louis Pasteur is the father of microbiology. 3. Gregor Mendel is the father of genetics. Which are correct?
A. 1 and 3 only
B. 2 and 3 only
C. 1, 2 and 3
D. 1 and 2 only
Discuss
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Correct Answer: Option C

Explanation:
Carolus Linnaeus, a Swedish botanist, is known as the father of taxonomy for formalizing the modern system of naming organisms (binomial nomenclature) and classification. Louis Pasteur, a French chemist, is considered the father of microbiology for his groundbreaking work on vaccination, microbial fermentation, and pasteurization. Gregor Mendel, an Austrian monk, is universally recognized as the father of genetics for his pioneering experiments on inheritance in pea plants. All statements are correct.
This question belongs to: Science Biology
Question #1856
Consider statements about cell biology: 1. Prokaryotic cells lack a true nucleus. 2. Eukaryotic cells have membrane-bound organelles. 3. Plant cells lack a cell wall. 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 C

Explanation:
Prokaryotic cells (bacteria, archaea) are characterized by the absence of a true, membrane-bound nucleus; their genetic material is located in a nucleoid region. Eukaryotic cells (plants, animals, fungi, protists) possess a true nucleus and various membrane-bound organelles like mitochondria, ER, and Golgi. Plant cells are distinguished from animal cells by the presence of a rigid cell wall made primarily of cellulose, along with chloroplasts and a large central vacuole. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1857
Consider statements about plant biology: 1. The stigma is the receptive part of the carpel. 2. The anther is the pollen-producing part of the stamen. 3. The ovary develops into the seed after fertilization. Which are correct?
A. 1 and 3 only
B. 2 and 3 only
C. 1 and 2 only
D. 1, 2 and 3
Discuss
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Correct Answer: Option C

Explanation:
The carpel is the female reproductive organ of a flower, consisting of the ovary, style, and stigma; the stigma is the terminal, sticky receptive surface where pollen grains land and germinate. The stamen is the male reproductive organ, consisting of the filament and the anther; the anther is the terminal sac where pollen grains (male gametophytes) are produced. After fertilization, the ovule develops into the seed, while the ovary wall matures and develops into the fruit. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1858
Consider statements about human anatomy: 1. The heart has four chambers. 2. The lungs are the primary organs of respiration. 3. The brain is protected by the skull. 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 human heart is a four-chambered muscular organ consisting of two upper atria (receiving chambers) and two lower ventricles (discharging chambers), ensuring complete separation of oxygenated and deoxygenated blood. The lungs are a pair of spongy, air-filled organs located on either side of the chest, serving as the primary site for gas exchange (respiration). The brain, the control center of the nervous system, is encased and protected by the bony cranium (skull). All statements are correct.
This question belongs to: Science Biology
Question #1859
Consider statements about human physiology: 1. The stomach secretes hydrochloric acid. 2. The small intestine is the primary site of absorption. 3. The large intestine absorbs most nutrients. Which are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1, 2 and 3
D. 1 and 3 only
Discuss
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Correct Answer: Option A

Explanation:
The stomach's gastric glands secrete hydrochloric acid (HCl), which creates an acidic medium necessary for the activation of pepsin and kills ingested microbes. The small intestine, with its vast surface area provided by villi and microvilli, is the primary site for the digestion and absorption of most nutrients into the bloodstream. The large intestine primarily absorbs water, electrolytes, and some vitamins produced by gut bacteria, but not the majority of nutrients. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1860
Consider statements about human diseases: 1. Cholera is a bacterial disease. 2. Polio is a viral disease. 3. Malaria is transmitted by a mosquito. 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 A

Explanation:
Cholera is an acute diarrheal illness caused by the bacterium Vibrio cholerae, typically transmitted through contaminated water. Polio (poliomyelitis) is a highly infectious viral disease caused by the poliovirus, which can lead to paralysis. Malaria is a life-threatening disease caused by Plasmodium parasites, which are transmitted to humans through the bites of infected female Anopheles mosquitoes. All three statements are correct.
This question belongs to: Science Biology

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