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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Question #1281
The enzyme that hydrolyzes triglycerides into fatty acids and glycerol is:
A. Lipase
B. Amylase
C. Protease
D. Nuclease
Discuss
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Correct Answer: Option A

Explanation:
Lipase, produced by the pancreas, breaks down dietary fats (triglycerides) into monoglycerides and free fatty acids, aided by bile salts.
This question belongs to: Science Biology
Question #1282
The structure that connects the hypothalamus to the pituitary gland is the:
A. Optic chiasm
B. Corpus callosum
C. Pineal stalk
D. Infundibulum
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Correct Answer: Option D

Explanation:
The infundibulum (pituitary stalk) physically connects the hypothalamus to the pituitary gland, transporting hormones and nerve signals.
This question belongs to: Science Biology
Question #1283
The process by which a cell engulfs large particles such as bacteria is:
A. Pinocytosis
B. Exocytosis
C. Osmosis
D. Phagocytosis
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Correct Answer: Option D

Explanation:
Phagocytosis is receptor-mediated or non-specific engulfment of large particles, forming a phagosome that fuses with lysosomes. Key in immune defense.
This question belongs to: Science Biology
Question #1284
The vitamin that is a component of the visual pigments in the retina is:
A. Vitamin A
B. Vitamin C
C. Vitamin D
D. Vitamin E
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Correct Answer: Option A

Explanation:
Retinal (vitamin A aldehyde) is part of rhodopsin and cone pigments. Deficiency causes night blindness and xerophthalmia.
This question belongs to: Science Biology
Question #1285
The scientist who proposed the 'indirect fit' model of enzyme action was:
A. Leonor Michaelis
B. Maud Menten
C. Daniel Koshland
D. Emil Fischer
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Correct Answer: Option C

Explanation:
Daniel Koshland proposed the induced fit model (1958), where enzyme active site changes shape upon substrate binding. Fischer had proposed lock-and-key.
This question belongs to: Science Biology
Question #1286
The disease caused by the Zika virus is transmitted by:
A. Tsetse fly
B. Aedes mosquito
C. Culex mosquito
D. Anopheles mosquito
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Correct Answer: Option B

Explanation:
Zika virus is primarily transmitted by Aedes aegypti and Aedes albopictus mosquitoes. It can cause microcephaly in fetuses. Anopheles transmits malaria, Culex filariasis/West Nile.
This question belongs to: Science Biology
Question #1287
The organelle that contains its own DNA and ribosomes and is involved in apoptosis is the:
A. Peroxisome
B. Endoplasmic reticulum
C. Lysosome
D. Mitochondria
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Correct Answer: Option D

Explanation:
Mitochondria release cytochrome c and other factors that activate caspases, initiating apoptosis. They have circular DNA and 70S ribosomes.
This question belongs to: Science Biology
Question #1288
The scientist who developed the first vaccine against yellow fever was:
A. Jonas Salk
B. Max Theiler
C. Edward Jenner
D. Louis Pasteur
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Correct Answer: Option B

Explanation:
Max Theiler developed the attenuated yellow fever vaccine (17D strain) in the 1930s, winning the Nobel Prize. Pasteur rabies, Jenner smallpox, Salk polio.
This question belongs to: Science Biology
Question #1289
The pigment that is responsible for the color of the iris in the eye is:
A. Carotene
B. Melanin
C. Hemoglobin
D. Rhodopsin
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Correct Answer: Option B

Explanation:
Melanin pigment in the iris determines eye color. High melanin: brown; low melanin: blue/green. Hemoglobin is in blood, carotene in plants, rhodopsin in retina.
This question belongs to: Science Biology
Question #1290
The technique used to analyze the entire protein complement of a cell is:
A. Metabolomics
B. Transcriptomics
C. Genomics
D. Proteomics
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Correct Answer: Option D

Explanation:
Proteomics involves large-scale study of proteins, their structures, and functions. Genomics is DNA, transcriptomics RNA, metabolomics metabolites.
This question belongs to: Science Biology
Question #1291
The disease caused by the deficiency of protein in children is:
A. Marasmus
B. Beriberi
C. Obesity
D. Kwashiorkor
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Correct Answer: Option D

Explanation:
Kwashiorkor results from severe protein deficiency with adequate calories, causing edema, pot belly, and skin lesions. Marasmus is overall calorie deficiency, beriberi thiamine.
This question belongs to: Science Biology
Question #1292
The hormone that stimulates the conversion of glucose to glycogen in the liver is:
A. Glucagon
B. Epinephrine
C. Cortisol
D. Insulin
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Correct Answer: Option D

Explanation:
Insulin activates glycogen synthase, promoting glycogenesis. Glucagon and epinephrine activate glycogen phosphorylase, promoting glycogenolysis.
This question belongs to: Science Biology
Question #1293
The process by which the neural plate forms the neural tube during embryonic development is:
A. Gastrulation
B. Cleavage
C. Organogenesis
D. Neurulation
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Correct Answer: Option D

Explanation:
Neurulation involves the folding of the neural plate to form the neural tube, which becomes the brain and spinal cord. Gastrulation forms germ layers.
This question belongs to: Science Biology
Question #1294
The vitamin that is essential for the carboxylation of glutamate residues in clotting factors is:
A. Vitamin C
B. Vitamin D
C. Vitamin A
D. Vitamin K
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Correct Answer: Option D

Explanation:
Vitamin K is a cofactor for γ-glutamyl carboxylase, which carboxylates glutamic acid in prothrombin and other factors, enabling calcium binding.
This question belongs to: Science Biology
Question #1295
The organ that produces bile and detoxifies the blood is the:
A. Spleen
B. Gall bladder
C. Pancreas
D. Liver
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Correct Answer: Option D

Explanation:
The liver is the body's largest internal organ, performing metabolism, detoxification, bile production, and protein synthesis. The gall bladder stores bile.
This question belongs to: Science Biology
Question #1296
The scientist who discovered the first antibiotic, penicillin, was:
A. Louis Pasteur
B. Alexander Fleming
C. Selman Waksman
D. Ernst Chain
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Correct Answer: Option B

Explanation:
Alexander Fleming accidentally discovered penicillin in 1928 when a mold (Penicillium) inhibited bacterial growth on a plate. Florey and Chain purified it.
This question belongs to: Science Biology
Question #1297
The pigment that gives blue-green algae their color is:
A. Chlorophyll a and phycocyanin
B. Chlorophyll b
C. Phycoerythrin
D. Fucoxanthin
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Correct Answer: Option A

Explanation:
Cyanobacteria (blue-green algae) contain chlorophyll a and phycobilins, mainly phycocyanin (blue) and phycoerythrin (red), hence blue-green color.
This question belongs to: Science Biology
Question #1298
The hormone that causes the let-down of milk during breastfeeding is:
A. Oxytocin
B. Estrogen
C. Prolactin
D. Progesterone
Discuss
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Correct Answer: Option A

Explanation:
Oxytocin from the posterior pituitary causes myoepithelial cells around mammary alveoli to contract, ejecting milk. Prolactin stimulates milk synthesis.
This question belongs to: Science Biology
Question #1299
The disease caused by the deficiency of vitamin B₁ is:
A. Pellagra
B. Beriberi
C. Scurvy
D. Rickets
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Correct Answer: Option B

Explanation:
Beriberi involves neurological and cardiovascular symptoms due to thiamine deficiency, common in polished rice diets. Scurvy is vitamin C, pellagra niacin, rickets D.
This question belongs to: Science Biology
Question #1300
The structure that allows the exchange of gases and nutrients between the mother and fetus is the:
A. Placenta
B. Amnion
C. Chorion
D. Umbilical cord
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Correct Answer: Option A

Explanation:
The placenta is a vascular organ formed from fetal chorion and maternal decidua, facilitating exchange without mixing blood. The umbilical cord connects fetus to placenta.
This question belongs to: Science Biology

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