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 48 of 103
Question #941
The vitamin essential for the absorption of calcium from the intestine is:
A. Vitamin C
B. Vitamin A
C. Vitamin B₁₂
D. Vitamin D
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Correct Answer: Option D

Explanation:
Vitamin D (calcitriol) stimulates the production of calcium-binding proteins in the intestinal lining, enhancing calcium absorption. Deficiency leads to rickets/osteomalacia. Vitamin A is for vision, C for collagen, B₁₂ for nerve function.
This question belongs to: Science Biology
Question #942
The organelle that contains enzymes for the Krebs cycle is:
A. Chloroplast
B. Nucleus
C. Mitochondrion
D. Golgi body
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Correct Answer: Option C

Explanation:
The matrix of mitochondria contains all enzymes of the Krebs cycle (except succinate dehydrogenase which is in the inner membrane). The nucleus contains DNA, chloroplasts contain Calvin cycle enzymes, Golgi modifies proteins.
This question belongs to: Science Biology
Question #943
The type of epithelial tissue that lines the inner surface of the stomach and intestines is:
A. Squamous epithelium
B. Stratified epithelium
C. Columnar epithelium
D. Cuboidal epithelium
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Correct Answer: Option C

Explanation:
Simple columnar epithelium lines the stomach, intestines, and gallbladder, and functions in secretion and absorption. It often has microvilli (brush border) or goblet cells. Squamous epithelium lines alveoli and blood vessels, cuboidal kidney tubules.
This question belongs to: Science Biology
Question #944
The disease caused by deficiency of vitamin C is:
A. Pellagra
B. Night blindness
C. Beriberi
D. Scurvy
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Correct Answer: Option D

Explanation:
Scurvy is characterized by bleeding gums, impaired wound healing, and anemia due to defective collagen synthesis from lack of vitamin C (ascorbic acid). Beriberi is B₁ deficiency, pellagra B₃, night blindness vitamin A.
This question belongs to: Science Biology
Question #945
The genetic material of a bacterium is located in the:
A. Mitochondria
B. Plasmid only
C. Nucleus
D. Nucleoid
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Correct Answer: Option D

Explanation:
Bacteria lack a true nucleus; their circular chromosome is concentrated in a region called the nucleoid. Plasmids are extra-chromosomal DNA but the main genome is in the nucleoid. Eukaryotes have a membrane-bound nucleus.
This question belongs to: Science Biology
Question #946
The scientist who coined the term 'cell' was:
A. Antonie van Leeuwenhoek
B. Robert Brown
C. Robert Hooke
D. Rudolf Virchow
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Correct Answer: Option C

Explanation:
Robert Hooke, in 1665, observed thin slices of cork under a compound microscope and saw box-like structures he named 'cells'. Leeuwenhoek observed live cells, Brown discovered the nucleus, Virchow proposed cells arise from cells.
This question belongs to: Science Biology
Question #947
Which of the following is an example of a unicellular organism?
A. Hydra
B. Mushroom
C. Earthworm
D. Paramecium
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Correct Answer: Option D

Explanation:
Paramecium is a unicellular ciliated protozoan found in freshwater. Earthworm and Hydra are multicellular animals, mushroom is a multicellular fungus. Unicellular organisms carry out all life processes within a single cell.
This question belongs to: Science Biology
Question #948
The organ that stores bile is the:
A. Pancreas
B. Liver
C. Duodenum
D. Gall bladder
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Correct Answer: Option D

Explanation:
The gall bladder is a small sac under the liver that stores and concentrates bile produced by the liver, releasing it into the duodenum when needed for fat digestion. The liver makes bile, pancreas produces digestive enzymes, duodenum is the entry point.
This question belongs to: Science Biology
Question #949
The hormone that stimulates uterine contractions during childbirth is:
A. Estrogen
B. Oxytocin
C. Prolactin
D. Relaxin
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Correct Answer: Option B

Explanation:
Oxytocin, released from the posterior pituitary, increases the frequency and strength of uterine contractions during labor via positive feedback. Prolactin stimulates milk production, estrogen helps uterine growth, relaxin relaxes pelvic ligaments.
This question belongs to: Science Biology
Question #950
The process of cell division that produces four haploid daughter cells is:
A. Mitosis
B. Meiosis
C. Binary fission
D. Amitosis
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Correct Answer: Option B

Explanation:
Meiosis consists of two successive divisions resulting in four genetically diverse haploid cells (gametes). Mitosis produces two identical diploid cells, amitosis is direct nuclear division, binary fission is prokaryotic asexual reproduction.
This question belongs to: Science Biology
Question #951
The waxy substance that waterproofs the leaf surface is:
A. Cutin
B. Suberin
C. Lignin
D. Cellulose
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Correct Answer: Option A

Explanation:
Cutin, along with waxes, forms the cuticle on the epidermis of leaves and stems, reducing water loss and providing protection. Lignin strengthens cell walls, cellulose is the wall polysaccharide, suberin is in cork cells and root endodermis.
This question belongs to: Science Biology
Question #952
The hormone that promotes the development of male secondary sexual characteristics is:
A. Estrogen
B. Progesterone
C. Testosterone
D. Prolactin
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Correct Answer: Option C

Explanation:
Testosterone, secreted by Leydig cells of the testes, is responsible for the development of male secondary sexual characteristics like facial hair, deepening of voice, and muscle growth. Estrogen and progesterone are female hormones.
This question belongs to: Science Biology
Question #953
Which of the following is a correct statement about a typical bacterium?
A. It has linear chromosomes.
B. It contains mitochondria.
C. It has a nuclear membrane.
D. Its DNA is circular and located in the nucleoid.
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Correct Answer: Option D

Explanation:
Bacteria are prokaryotes with a single circular chromosome in a nucleoid region, without a nuclear membrane. They lack membrane-bound organelles like mitochondria. Their chromosomes are not linear; eukaryotes have linear chromosomes.
This question belongs to: Science Biology
Question #954
The pigment that gives red algae their color is:
A. Fucoxanthin
B. Carotene
C. Phycoerythrin
D. Chlorophyll
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Correct Answer: Option C

Explanation:
Phycoerythrin is a red pigment found in red algae (Rhodophyta), masking the green chlorophyll. Fucoxanthin is brown (brown algae), chlorophyll is green, carotene is orange/yellow. Phycoerythrin absorbs blue light, allowing red algae to live in deeper waters.
This question belongs to: Science Biology
Question #955
The human embryo gets nutrition from the mother through the:
A. Amnion
B. Placenta
C. Umbilical cord
D. Yolk sac
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Correct Answer: Option B

Explanation:
The placenta is the organ that attaches to the uterine wall and facilitates exchange of nutrients, oxygen, and wastes between mother and fetus. The umbilical cord connects the fetus to the placenta. The amnion forms a protective fluid-filled sac.
This question belongs to: Science Biology
Question #956
The bacterium used in the production of acetic acid (vinegar) is:
A. Streptomyces
B. Lactobacillus
C. Escherichia coli
D. Acetobacter aceti
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Correct Answer: Option D

Explanation:
Acetobacter aceti oxidizes ethanol to acetic acid under aerobic conditions, used in vinegar production. Lactobacillus produces lactic acid, Streptomyces produces antibiotics, E. coli is used in genetic engineering but not vinegar.
This question belongs to: Science Biology
Question #957
The structure in the kidney that concentrates urine is the:
A. Distal tubule
B. Proximal tubule
C. Bowman's capsule
D. Loop of Henle
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Correct Answer: Option D

Explanation:
The loop of Henle creates a countercurrent multiplier system in the medulla, establishing an osmotic gradient that allows the collecting duct to reabsorb water and produce concentrated urine. The other parts handle filtration, reabsorption, and secretion.
This question belongs to: Science Biology
Question #958
The phenomenon of a plant growing towards gravity is called:
A. Geotropism
B. Hydrotropism
C. Phototropism
D. Thigmotropism
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Correct Answer: Option A

Explanation:
Geotropism (gravitropism) is directional growth in response to gravity; roots show positive geotropism (downward), shoots negative (upward). Phototropism is light-directed, thigmotropism touch, hydrotropism water.
This question belongs to: Science Biology
Question #959
The scientist who proposed the 'germ theory of disease' was:
A. Joseph Lister
B. Alexander Fleming
C. Robert Koch
D. Louis Pasteur
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Correct Answer: Option D

Explanation:
Louis Pasteur provided strong evidence that microorganisms cause disease and developed pasteurization to kill pathogens. Koch formalized criteria linking specific microbes to specific diseases. Fleming discovered penicillin, Lister introduced antiseptic surgery.
This question belongs to: Science Biology
Question #960
The type of tissue that supports and binds other tissues is:
A. Connective tissue
B. Muscle tissue
C. Epithelial tissue
D. Nervous tissue
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Correct Answer: Option A

Explanation:
Connective tissues (bone, cartilage, blood, adipose) provide structural framework, support, and bind organs. Epithelial covers surfaces, muscle enables movement, nervous conducts impulses.
This question belongs to: Science Biology

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