Biology MCQs

Science

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.

2054
Total Questions

Practice Questions

Page 89 of 103
Question #1761
Consider statements about human physiology: 1. The liver produces bile. 2. The pancreas produces insulin. 3. The gall bladder produces digestive enzymes. Which are correct?
A. 2 and 3 only
B. 1 and 3 only
C. 1, 2 and 3
D. 1 and 2 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The liver continuously synthesizes bile, which is essential for fat emulsification. The pancreas acts as both an exocrine and endocrine gland; its Islets of Langerhans produce insulin and glucagon. The gall bladder only stores, concentrates, and releases bile; it does not produce any digestive enzymes. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1762
Consider statements about human senses: 1. The retina contains photoreceptors. 2. The cochlea is involved in hearing. 3. Taste buds are located only on the tongue. Which are correct?
A. 1 and 2 only
B. 1, 2 and 3
C. 1 and 3 only
D. 2 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
The retina is the inner lining of the eye containing rods and cones, the photoreceptor cells for vision. The cochlea is a spiral-shaped cavity in the inner ear containing the organ of Corti, essential for converting sound vibrations into nerve impulses. Taste buds are primarily on the tongue but are also found on the soft palate, epiglottis, and upper esophagus. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1763
Consider statements about human skin: 1. The epidermis is the outermost layer. 2. Sweat glands help in thermoregulation. 3. Melanin protects against UV radiation. Which are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The skin consists of the outer epidermis and the inner dermis. The epidermis contains melanocytes that produce melanin, a pigment that absorbs harmful ultraviolet radiation, protecting deeper tissues. Sweat glands in the dermis secrete sweat onto the skin surface; its evaporation removes heat, playing a crucial role in body thermoregulation. All statements are correct.
This question belongs to: Science Biology
Question #1764
Consider statements about plant reproduction: 1. The anther produces pollen. 2. The ovary develops into the fruit. 3. Self-pollination increases genetic diversity. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 2 only
D. 1 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
The anther is the male reproductive part of the flower where microspores develop into pollen grains. After fertilization, the ovary wall matures and develops into the fruit, enclosing the seeds. Self-pollination involves the transfer of pollen to the stigma of the same flower or plant, resulting in offspring genetically identical to the parent, thus decreasing, not increasing, genetic diversity. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1765
Consider statements about human diseases: 1. Tuberculosis is caused by a virus. 2. Polio is caused by a bacterium. 3. Tetanus affects the nervous system. Which are correct?
A. 1 and 2 only
B. 3 only
C. 2 and 3 only
D. 1, 2 and 3
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Tuberculosis is a bacterial disease caused by Mycobacterium tuberculosis, primarily affecting the lungs. Polio is a viral disease caused by the poliovirus, attacking the nervous system. Tetanus is caused by the bacterium Clostridium tetani, which produces a neurotoxin that causes severe muscle spasms and affects the nervous system. Thus, only statement 3 is correct.
This question belongs to: Science Biology
Question #1766
Consider statements about human immunity: 1. Skin is a physical barrier. 2. Phagocytosis is a specific immune response. 3. Memory cells provide long-term immunity. Which are correct?
A. 1 and 3 only
B. 2 and 3 only
C. 1, 2 and 3
D. 1 and 2 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
The skin and mucous membranes act as primary physical barriers in innate immunity, preventing pathogen entry. Phagocytosis by macrophages and neutrophils is a non-specific (innate) cellular defense mechanism, not a specific immune response. Memory B and T cells are produced during the primary specific immune response and provide rapid, long-lasting immunity upon re-exposure. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1767
Consider statements about human nutrition: 1. Fats provide more energy per gram than carbohydrates. 2. Roughage prevents constipation. 3. Water is not considered a nutrient. Which are correct?
A. 1, 2 and 3
B. 2 and 3 only
C. 1 and 3 only
D. 1 and 2 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Fats yield about 9 kcal/g of energy, more than double the 4 kcal/g provided by carbohydrates and proteins. Roughage (dietary fiber) adds bulk to the stool and stimulates peristalsis, preventing constipation. Water is an essential nutrient, crucial for hydration, solvent functions, and temperature regulation, though it provides no calories. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1768
Consider statements about vitamins: 1. Vitamin A is stored in the liver. 2. Vitamin B complex is water-soluble. 3. Excess Vitamin D is easily excreted. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 3 only
D. 1 and 2 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Vitamin A is a fat-soluble vitamin stored primarily in the liver, and excess can lead to toxicity. The B-complex vitamins are water-soluble and generally not stored in the body in significant amounts. Fat-soluble vitamins (A, D, E, K) are stored in body fat and liver, making excess Vitamin D difficult to excrete, potentially causing hypervitaminosis D. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1769
Consider statements about genetics: 1. DNA replication is semi-conservative. 2. Transcription occurs in the cytoplasm. 3. Translation occurs at ribosomes. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 2 only
D. 1 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
DNA replication is semi-conservative, meaning each new DNA molecule contains one original parental strand and one newly synthesized strand. Transcription, the synthesis of mRNA from a DNA template, occurs in the nucleus of eukaryotes, not the cytoplasm. Translation, the synthesis of proteins from mRNA, occurs at ribosomes in the cytoplasm or on the rough ER. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1770
Consider statements about evolution: 1. Mutations provide raw material for evolution. 2. Genetic drift occurs in large populations. 3. Speciation can result from geographic isolation. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 3 only
D. 1 and 2 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Mutations are random changes in DNA that create new alleles, providing the raw genetic variation necessary for natural selection. Genetic drift is the random change in allele frequencies, which has a significant effect primarily in small, isolated populations, not large ones. Geographic isolation prevents gene flow between populations, eventually leading to reproductive isolation and speciation. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1771
Consider statements about ecology: 1. Primary succession occurs on bare rock. 2. Secondary succession occurs after a forest fire. 3. Climax community is unstable. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 3 only
D. 1 and 2 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Primary succession begins on lifeless, barren substrates like bare rock, where no soil exists initially. Secondary succession occurs in areas where an existing community has been destroyed by disturbances like forest fires, floods, or logging, but soil remains. A climax community is the final, stable, and self-perpetuating stage of ecological succession, in equilibrium with the environment. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1772
Consider statements about environment: 1. The greenhouse effect is entirely unnatural. 2. Deforestation contributes to global warming. 3. Ozone depletion causes skin cancer. Which are correct?
A. 2 and 3 only
B. 1, 2 and 3
C. 1 and 2 only
D. 1 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
The greenhouse effect is a natural process that keeps Earth warm; the problem is the enhanced greenhouse effect due to human activities. Deforestation reduces the number of trees absorbing CO2, increasing atmospheric greenhouse gases and contributing to global warming. Ozone layer depletion allows more harmful UV-B radiation to reach Earth, significantly increasing the risk of skin cancers. Thus, statements 2 and 3 are correct.
This question belongs to: Science Biology
Question #1773
Consider statements about microorganisms: 1. Algae are photosynthetic. 2. Protozoa are multicellular. 3. Fungi reproduce by spores. Which are correct?
A. 1 and 3 only
B. 1, 2 and 3
C. 1 and 2 only
D. 2 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Algae are a diverse group of photosynthetic, eukaryotic organisms ranging from unicellular to multicellular forms. Protozoa are unicellular, heterotrophic eukaryotic organisms, not multicellular. Fungi typically reproduce asexually and sexually through the formation of spores, which are dispersed to form new individuals. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1774
Consider statements about biotechnology: 1. Plasmids are used as vectors. 2. Restriction enzymes are found in viruses. 3. PCR requires DNA polymerase. Which are correct?
A. 1 and 3 only
B. 1 and 2 only
C. 2 and 3 only
D. 1, 2 and 3
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Plasmids are small, circular, extrachromosomal DNA molecules in bacteria widely used as cloning vectors in genetic engineering. Restriction enzymes are part of the bacterial immune system, found in bacteria and archaea, not viruses, protecting them against bacteriophages. Polymerase Chain Reaction (PCR) requires a thermostable DNA polymerase (like Taq) to synthesize new DNA strands. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1775
Consider statements about animal husbandry: 1. Poultry provides eggs and meat. 2. Apiculture increases crop yield. 3. Dairy farming focuses on fish production. Which are correct?
A. 1, 2 and 3
B. 2 and 3 only
C. 1 and 3 only
D. 1 and 2 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Poultry farming involves rearing birds like chickens for the production of eggs (layers) and meat (broilers). Apiculture (beekeeping) not only produces honey but also significantly increases crop yields through enhanced pollination by bees. Dairy farming focuses on the breeding and rearing of cattle, buffaloes, etc., for milk production, not fish (which is pisciculture). Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1776
Consider statements about scientists: 1. Antonie van Leeuwenhoek discovered bacteria. 2. Robert Koch established postulates for disease causation. 3. Alexander Fleming discovered the antibiotic streptomycin. Which are correct?
A. 1 and 3 only
B. 1, 2 and 3
C. 1 and 2 only
D. 2 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Antonie van Leeuwenhoek was the first to observe and describe living microorganisms, including bacteria, using his single-lens microscopes. Robert Koch formulated Koch's postulates, a set of criteria to establish that a specific microorganism causes a specific disease. Alexander Fleming discovered penicillin; streptomycin was discovered by Selman Waksman. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1777
Consider statements about cell biology: 1. The plasma membrane is selectively permeable. 2. The nucleolus is the site of protein synthesis. 3. Lysosomes contain digestive enzymes. Which are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1, 2 and 3
D. 1 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The plasma membrane is selectively permeable, regulating the entry and exit of specific molecules into and out of the cell. Lysosomes are membrane-bound organelles containing powerful hydrolytic (digestive) enzymes for intracellular digestion. The nucleolus is the site of ribosomal RNA (rRNA) synthesis and ribosome assembly, not protein synthesis, which occurs at ribosomes. Thus, statements 1 and 3 are correct.
This question belongs to: Science Biology
Question #1778
Consider statements about plant biology: 1. Transpiration occurs through stomata. 2. Guttaion occurs through hydathodes. 3. Phloem transports water upwards. Which are correct?
A. 2 and 3 only
B. 1 and 3 only
C. 1 and 2 only
D. 1, 2 and 3
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Transpiration is the loss of water vapor primarily through the stomata on the leaf surface. Guttation is the exudation of liquid water from the margins of leaves through specialized structures called hydathodes, usually at night when root pressure is high. Phloem is responsible for the translocation of organic food (bidirectional), while xylem transports water and minerals upwards. Thus, statements 1 and 2 are correct.
This question belongs to: Science Biology
Question #1779
Consider statements about human anatomy: 1. The biceps is a muscle in the arm. 2. The quadriceps is a muscle in the thigh. 3. The diaphragm separates the thorax and abdomen. Which are correct?
A. 1 and 2 only
B. 1 and 3 only
C. 1, 2 and 3
D. 2 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
The biceps brachii is a two-headed muscle located in the upper arm, responsible for flexing the elbow. The quadriceps femoris is a large, four-headed muscle group in the front of the thigh, extending the knee. The diaphragm is a dome-shaped skeletal muscle that forms the floor of the thoracic cavity and the roof of the abdominal cavity, crucial for breathing. All statements are correct.
This question belongs to: Science Biology
Question #1780
Consider statements about human physiology: 1. The hypothalamus regulates body temperature. 2. The cerebellum controls voluntary muscle coordination. 3. The medulla controls reflex actions like swallowing. Which are correct?
A. 1, 2 and 3
B. 1 and 2 only
C. 2 and 3 only
D. 1 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
The hypothalamus is the primary thermoregulatory center, maintaining body temperature through sweating or shivering. The cerebellum coordinates voluntary movements, ensuring smooth and accurate muscle activity and balance. The medulla oblongata contains vital reflex centers controlling involuntary actions such as swallowing, coughing, sneezing, and vomiting. All three statements are anatomically and physiologically correct.
This question belongs to: Science Biology

More Science Topics

chemistry MCQs
Physics MCQs
Today's Top Topics
Physics 1287 chemistry 1089 Biology 2054
Explore Subjects
Accountancy and Statistics 3179 Science 4430 Geography GK 6121 Computer 5279 English 15164
Practice Mix
The average of 40,50,60,70 is
I ___ a lot of work today and I'm exhausted.
The principal giving Rs. 184800 SI in 8 years at 11%
The noun 'homework' takes which verb?
The forest ______ we camped in is dense.