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 83 of 103
Question #1641
Consider the following statements about DNA fingerprinting:
1. It uses VNTRs (variable number tandem repeats).
2. It can be used in paternity testing.
3. It requires amplification by PCR.
Which of the above is/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 D

Explanation:
DNA fingerprinting analyzes VNTRs, often amplified by PCR, and is used in forensics and paternity. All three are correct.
This question belongs to: Science Biology
Question #1642
Assertion (A): The appendix is a vestigial organ.
Reason (R): It has no known function in the human body.
A. A is true, but R is false.
B. Both A and R are true, and R is the correct explanation.
C. Both A and R are true, but R is not the correct explanation.
D. A is false, but R is true.
Discuss
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Correct Answer: Option A

Explanation:
The appendix is considered vestigial (reduced and non-essential), but recent studies suggest it may have a minor immune function or serve as a reservoir for gut bacteria. So R is not entirely true (it may have a function). Thus, A is true but R is false (no function is an oversimplification).
This question belongs to: Science Biology
Question #1643
Which of the following statements about protein structure is correct?
A. Denaturation breaks peptide bonds.
B. The secondary structure includes alpha helices and beta sheets.
C. Disulfide bonds are part of the secondary structure.
D. The primary structure is the overall 3D shape.
Discuss
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Correct Answer: Option B

Explanation:
Secondary structure refers to local folding patterns like α-helices and β-sheets. Primary is amino acid sequence; tertiary is 3D folding; disulfide bonds are tertiary/quaternary; denaturation disrupts non-covalent bonds, not peptide bonds.
This question belongs to: Science Biology
Question #1644
Consider the following statements about viruses:
1. The tobacco mosaic virus was the first virus discovered.
2. Viruses can have a protein coat called capsid.
3. Viruses can reproduce outside host cells.
Which of the above is/are correct?
A. 1 and 2 only
B. 1 and 3 only
C. 2 and 3 only
D. 1, 2, and 3
Discuss
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Correct Answer: Option A

Explanation:
TMV was discovered by Ivanovsky. Viruses have a capsid. They require host cells to replicate, so 3 is incorrect.
This question belongs to: Science Biology
Question #1645
Assertion (A): Mycorrhizae are symbiotic associations between fungi and plant roots.
Reason (R): The fungus provides water and minerals to the plant and receives sugars in return.
A. A false, R true.
B. Both A and R are true, and R is the correct explanation.
C. Both A and R are true, but R is not the correct explanation.
D. A true, R false.
Discuss
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Correct Answer: Option B

Explanation:
Mycorrhizae enhance nutrient and water uptake for plants, and the fungus benefits from photosynthetic carbohydrates. It’s a mutualistic symbiosis. R correctly explains A.
This question belongs to: Science Biology
Question #1646
Which of the following statements about the cell is correct?
A. The cell is the basic unit of life.
B. Prokaryotic cells contain mitochondria.
C. Viruses are cells.
D. All cells have a nucleus.
Discuss
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Correct Answer: Option A

Explanation:
The cell theory states that the cell is the fundamental unit of structure and function. Not all cells have a nucleus (prokaryotes), prokaryotes lack mitochondria, viruses are not cells.
This question belongs to: Science Biology
Question #1647
Consider the following statements about the human heart:
1. The right atrium receives blood from the vena cavae.
2. The left ventricle pumps blood to the lungs.
3. The septum separates the left and right sides.
Which of the above is/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 D

Explanation:
The right atrium receives deoxygenated blood; the left ventricle pumps to the body (not lungs). Septum divides the heart. So 2 is incorrect.
This question belongs to: Science Biology
Question #1648
Assertion (A): The menstrual cycle ceases during pregnancy.
Reason (R): High levels of progesterone and estrogen inhibit FSH and LH release.
A. A true, R false.
B. Both A and R are true, and R is the correct explanation.
C. Both A and R are true, but R is not the correct explanation.
D. A false, R true.
Discuss
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Correct Answer: Option B

Explanation:
During pregnancy, high progesterone and estrogen from the corpus luteum and placenta suppress gonadotropin secretion, preventing follicular development and menstruation. R correctly explains A.
This question belongs to: Science Biology
Question #1649
Which of the following statements about evolution is correct?
A. Natural selection always leads to new species formation.
B. Fossils show that life forms have changed over time.
C. Homologous organs have different basic structures.
D. Darwin’s theory is based on inheritance of acquired characters.
Discuss
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Correct Answer: Option B

Explanation:
Fossils provide a record of past life, showing changes. Homologous organs share common anatomy, Darwin proposed natural selection, Lamarck inheritance of acquired characters, natural selection can but not always lead to speciation.
This question belongs to: Science Biology
Question #1650
Identify the correct statement about the digestive enzymes:
A. Pepsinogen is active without HCl.
B. Sucrase breaks down lactose.
C. Trypsin is secreted by the pancreas.
D. Ptyalin is a lipase.
Discuss
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Correct Answer: Option C

Explanation:
Trypsin is a pancreatic protease. Ptyalin is an amylase, pepsinogen requires HCl for activation, sucrase acts on sucrose, lactase on lactose.
This question belongs to: Science Biology
Question #1651
Consider the following statements about the skin:
1. The epidermis is the outermost layer.
2. Melanin protects against UV radiation.
3. Sebaceous glands produce sweat.
Which of the above is/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:
Epidermis is outer layer, melanin absorbs UV. Sebaceous glands produce sebum (oil), sweat is from sudoriferous glands. So 3 is incorrect.
This question belongs to: Science Biology
Question #1652
Assertion (A): Restriction enzymes are used in recombinant DNA technology.
Reason (R): They cut DNA at specific recognition sequences.
A. Both A and R are true, and R is the correct explanation.
B. Both A and R are true, but R is not the correct explanation.
C. A true, R false.
D. A false, R true.
Discuss
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Correct Answer: Option A

Explanation:
Restriction endonucleases cut DNA at specific palindrome sequences, generating sticky or blunt ends, which can be ligated to vector DNA. This is the basis of genetic engineering. R explains A.
This question belongs to: Science Biology
Question #1653
Which of the following statements about the pituitary gland is correct?
A. It is often called the master gland.
B. It produces insulin.
C. It is located in the abdomen.
D. It is not connected to the hypothalamus.
Discuss
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Correct Answer: Option A

Explanation:
The pituitary, located at the base of the brain, controls many endocrine glands via its hormones, earning the name 'master gland'. Insulin is from pancreas; it is connected to hypothalamus by infundibulum.
This question belongs to: Science Biology
Question #1654
Identify the INCORRECT statement about the human brain:
A. The medulla oblongata controls vomiting.
B. The hypothalamus regulates body temperature.
C. The cerebellum is responsible for voluntary muscle movements.
D. The cerebrum is divided into two hemispheres.
Discuss
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Correct Answer: Option C

Explanation:
The cerebellum coordinates movement and balance; voluntary movements are initiated in the cerebrum. So B is incorrect.
This question belongs to: Science Biology
Question #1655
Consider the following statements about the immune system:
1. Macrophages are phagocytic cells.
2. B cells produce antibodies.
3. T cells are part of innate immunity.
Which of the above is/are correct?
A. 1 and 2 only
B. 1, 2, and 3
C. 1 and 3 only
D. 2 and 3 only
Discuss
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Correct Answer: Option A

Explanation:
Macrophages phagocytose; B cells make antibodies. T cells are part of adaptive immunity, not innate. So 3 is incorrect.
This question belongs to: Science Biology
Question #1656
Assertion (A): The Krebs cycle occurs in the mitochondrial matrix.
Reason (R): The enzymes for the Krebs cycle are soluble in the matrix.
A. A true, R false.
B. A false, R true.
C. Both A and R are true, and R is the correct explanation.
D. Both A and R are true, but R is not the correct explanation.
Discuss
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Correct Answer: Option C

Explanation:
The mitochondrial matrix contains all Krebs cycle enzymes (except succinate dehydrogenase). Thus, the location is due to enzyme presence. R correctly explains A.
This question belongs to: Science Biology
Question #1657
Which of the following statements about the circulatory system is correct?
A. The heart of a fish has four chambers.
B. Blood pressure is highest in the veins.
C. The foramen ovale is a valve in the adult heart.
D. The hepatic portal vein carries blood from the intestine to the liver.
Discuss
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Correct Answer: Option D

Explanation:
The hepatic portal system directs nutrient-rich blood from intestines to liver. Blood pressure is highest in arteries; fish have two-chambered heart; foramen ovale is a fetal structure that closes after birth.
This question belongs to: Science Biology
Question #1658
Identify the correct statement about respiration:
A. External respiration occurs in the tissues.
B. The primary stimulus for breathing is low oxygen.
C. The diaphragm moves upward during inhalation.
D. Carbon dioxide is transported mainly as bicarbonate ions.
Discuss
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Correct Answer: Option D

Explanation:
About 70% CO₂ is carried as bicarbonate. The main stimulus is high CO₂; external respiration is in lungs; diaphragm moves downward (contracts) during inhalation.
This question belongs to: Science Biology
Question #1659
Consider the following statements about the plant root:
1. Root hairs increase absorption surface area.
2. The root cap protects the root tip.
3. The zone of elongation is responsible for root growth in length.
Which of the above is/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 D

Explanation:
All are correct: root hairs absorb water/minerals; root cap protects meristem; elongation zone extends the root.
This question belongs to: Science Biology
Question #1660
Assertion (A): Fishes are ammonotelic.
Reason (R): Ammonia is highly toxic and requires a large amount of water for excretion, which is available in aquatic environments.
A. A true, R false.
B. Both A and R are true, but R is not the correct explanation.
C. Both A and R are true, and R is the correct explanation.
D. A false, R true.
Discuss
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Correct Answer: Option C

Explanation:
Ammonotelic organisms excrete ammonia directly into water, which dilutes it. This is feasible for fishes. The reason correctly explains why they are ammonotelic.
This question belongs to: Science Biology

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