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 #981
The muscle type that is under voluntary control is:
A. Skeletal muscle
B. Cardiac muscle
C. Visceral muscle
D. Smooth muscle
Discuss
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Correct Answer: Option A

Explanation:
Skeletal muscle, attached to bones, is striated and under conscious (voluntary) control. Smooth and cardiac muscles are involuntary. Skeletal muscles are responsible for locomotion and posture.
This question belongs to: Science Biology
Question #982
The organ that removes old red blood cells and stores iron is the:
A. Liver
B. Spleen
C. Bone marrow
D. Kidney
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Correct Answer: Option D

Explanation:
The spleen filters blood, removing aged or damaged RBCs, recycles iron, and stores platelets. The liver also processes hemoglobin products, but the spleen is the primary organ for RBC removal. The kidneys filter blood but don't remove RBCs.
This question belongs to: Science Biology
Question #983
The plant tissue that provides mechanical support and is dead at maturity is:
A. Collenchyma
B. Parenchyma
C. Aerenchyma
D. Sclerenchyma
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Correct Answer: Option D

Explanation:
Sclerenchyma cells have thick, lignified secondary walls and are often dead at maturity, providing rigid structural support. Fibers and sclereids are examples. Parenchyma is living and thin-walled, collenchyma living with uneven thickening, aerenchyma has air spaces.
This question belongs to: Science Biology
Question #984
The animal that lays eggs and has a beak but no teeth is:
A. Whale
B. Kangaroo
C. Bat
D. Platypus
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Correct Answer: Option D

Explanation:
The platypus is a monotreme (egg-laying mammal) with a duck-like beak, no teeth, and webbed feet. Bats and whales are placental mammals, kangaroo is a marsupial. Platypus is found in Australia.
This question belongs to: Science Biology
Question #985
The substance used to preserve dead biological specimens is:
A. Acetone
B. Alcohol
C. Formalin
D. Glycerin
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Correct Answer: Option C

Explanation:
Formalin (37-40% formaldehyde solution) is a common fixative and preservative for biological specimens, preventing decay by cross-linking proteins. Alcohol is also used but formalin is standard. Acetone is a solvent, glycerin a humectant.
This question belongs to: Science Biology
Question #986
The enzyme that converts lactose into glucose and galactose is:
A. Amylase
B. Maltase
C. Sucrase
D. Lactase
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Correct Answer: Option D

Explanation:
Lactase is a brush border enzyme in the small intestine that hydrolyzes lactose (milk sugar) into its constituent monosaccharides. Maltase acts on maltose, sucrase on sucrose, amylase on starch. Lactose intolerance results from lactase deficiency.
This question belongs to: Science Biology
Question #987
The hormone that stimulates the thyroid gland to release thyroxine is:
A. FSH
B. ACTH
C. TSH
D. LH
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Correct Answer: Option C

Explanation:
Thyroid-stimulating hormone (TSH), secreted by the anterior pituitary, binds to receptors on thyroid follicular cells and stimulates them to produce and release T₃ and T₄. ACTH stimulates adrenal cortex, FSH and LH target gonads.
This question belongs to: Science Biology
Question #988
The type of cell division that occurs during growth and repair is:
A. Fragmentation
B. Mitosis
C. Binary fission
D. Meiosis
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Correct Answer: Option B

Explanation:
Mitosis is the equational division that produces genetically identical daughter cells, used for growth, development, and tissue repair. Meiosis produces gametes, binary fission is prokaryotic, fragmentation is asexual reproduction.
This question belongs to: Science Biology
Question #989
The process of eliminating undigested food from the body is:
A. Absorption
B. Assimilation
C. Egestion
D. Digestion
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Correct Answer: Option C

Explanation:
Egestion (defecation) is the removal of undigested solid waste from the digestive tract. Absorption is uptake of nutrients, assimilation is incorporation into cells, digestion is breakdown of food.
This question belongs to: Science Biology
Question #990
The gland that produces tears is the:
A. Lacrimal gland
B. Sublingual gland
C. Ceruminous gland
D. Parotid gland
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Correct Answer: Option A

Explanation:
Lacrimal glands, located above the outer corner of each eye, produce tears that lubricate and protect the eye surface. Parotid and sublingual are salivary glands, ceruminous glands produce ear wax.
This question belongs to: Science Biology
Question #991
The process of taking in food through the mouth is called:
A. Digestion
B. Ingestion
C. Egestion
D. Absorption
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Correct Answer: Option B

Explanation:
Ingestion is the act of taking food and liquids into the body through the mouth. Digestion is the breakdown, absorption is nutrient uptake, egestion is waste elimination. Ingestion is the first step in nutrition.
This question belongs to: Science Biology
Question #992
The structure that protects the spinal cord is the:
A. Pelvis
B. Rib cage
C. Vertebral column
D. Skull
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Correct Answer: Option C

Explanation:
The vertebral column (spine) consists of vertebrae stacked to form a canal that encloses and protects the spinal cord. The skull protects the brain, rib cage the thoracic organs, pelvis the pelvic organs.
This question belongs to: Science Biology
Question #993
The branch of biology concerned with the study of insects is:
A. Ichthyology
B. Herpetology
C. Ornithology
D. Entomology
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Correct Answer: Option D

Explanation:
Entomology is the study of insects. Ichthyology is fish, herpetology reptiles and amphibians, ornithology birds. Insects are the most diverse group of animals.
This question belongs to: Science Biology
Question #994
The pigment that gives urine its yellow color is:
A. Bilirubin
B. Urobilin
C. Melanin
D. Hemoglobin
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Correct Answer: Option B

Explanation:
Urobilin (urochrome) is a breakdown product of bilirubin, giving urine its characteristic yellow color. Bilirubin is in bile, hemoglobin in red blood cells, melanin in skin. Dark yellow urine indicates concentrated urine due to dehydration.
This question belongs to: Science Biology
Question #995
The scientist who discovered that DNA is the genetic material in bacteriophages was:
A. Meselson and Stahl
B. Avery, MacLeod, McCarty
C. Hershey and Chase
D. Watson and Crick
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Correct Answer: Option C

Explanation:
Hershey and Chase (1952) used radioactive isotopes (³²P and ³⁵S) to show that DNA, not protein, enters bacteria during T2 phage infection and is the genetic material. Avery et al. earlier showed transforming principle was DNA. Watson and Crick determined structure, Meselson-Stahl replication mode.
This question belongs to: Science Biology
Question #996
The enzyme that catalyzes the conversion of glucose to glucose-6-phosphate is:
A. Phosphofructokinase
B. Hexokinase
C. Glucose-6-phosphatase
D. Pyruvate kinase
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Correct Answer: Option B

Explanation:
Hexokinase phosphorylates glucose to glucose-6-phosphate using ATP, the first step of glycolysis. Phosphofructokinase is the third step, pyruvate kinase the last, glucose-6-phosphatase reverses the reaction in gluconeogenesis.
This question belongs to: Science Biology
Question #997
The type of inflorescence in which flowers are borne on a flattened receptacle, as in sunflower, is:
A. Raceme
B. Umbel
C. Spike
D. Capitulum
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Correct Answer: Option D

Explanation:
Capitulum (head) is characteristic of the Asteraceae family, where numerous small florets are arranged on a flattened disc. Raceme has flowers on pedicels along an elongated axis, spike sessile, umbel umbrella-like. Sunflower inflorescence is a capitulum.
This question belongs to: Science Biology
Question #998
The vitamin that prevents neural tube defects during fetal development is:
A. Vitamin B₁
B. Folic acid (B₉)
C. Vitamin C
D. Vitamin B₁₂
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Correct Answer: Option B

Explanation:
Folic acid is crucial for DNA synthesis and cell division; deficiency during early pregnancy increases risk of neural tube defects like spina bifida. Supplementation is recommended. B₁ is for carbohydrate metabolism, B₁₂ for nerve function, C for collagen.
This question belongs to: Science Biology
Question #999
The hormone that inhibits the secretion of gastric juice is:
A. Cholecystokinin
B. Secretin
C. Gastrin
D. Gastric inhibitory peptide
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Correct Answer: Option D

Explanation:
GIP (glucose-dependent insulinotropic peptide) is released from the small intestine in response to fat and glucose, inhibiting gastric secretion and motility. Gastrin stimulates acid secretion, secretin stimulates bicarbonate, CCK stimulates gallbladder contraction.
This question belongs to: Science Biology
Question #1000
The scientist who proposed the 'mutation theory' of evolution was:
A. Alfred Wallace
B. Jean-Baptiste Lamarck
C. Charles Darwin
D. Hugo de Vries
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Correct Answer: Option D

Explanation:
Hugo de Vries proposed the mutation theory in 1901 based on his experiments with evening primrose (Oenothera lamarckiana), suggesting that new species arise suddenly through large mutations. Darwin proposed gradual natural selection, Lamarck use-disuse, Wallace independently natural selection.
This question belongs to: Science Biology

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