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 82 of 103
Question #1621
Which of the following statements about fermentation is correct?
A. It produces a large amount of ATP.
B. It requires oxygen.
C. In muscle cells, it produces ethanol.
D. In yeast, it produces ethanol and carbon dioxide.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Alcoholic fermentation in yeast produces ethanol and CO₂. Fermentation is anaerobic, yields 2 ATP, and in muscles produces lactic acid.
This question belongs to: Science Biology
Question #1622
Identify the correct statement about the human reproductive system:
A. The ovum is released from the uterus during ovulation.
B. The vas deferens carries sperm from the testes to the urethra.
C. Fertilization occurs in the ovary.
D. The prostate gland produces sperm.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Vas deferens transports sperm. The ovum is released from the ovary, fertilization occurs in the fallopian tube, prostate produces seminal fluid.
This question belongs to: Science Biology
Question #1623
Consider the following statements about vitamins:
1. Vitamin B₁ is thiamine.
2. Vitamin B₂ is riboflavin.
3. Vitamin B₆ is pyridoxine.
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
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
All three are correct chemical names: B₁ thiamine, B₂ riboflavin, B₆ pyridoxine.
This question belongs to: Science Biology
Question #1624
Assertion (A): The genetic code is universal.
Reason (R): The same codon codes for the same amino acid in all organisms.
A. A false, R true.
B. Both A and R are true, and R is the correct explanation.
C. A true, R false.
D. Both A and R are true, but R is not the correct explanation.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Universality means that with few exceptions, codons specify the same amino acids across species. This is the evidence, so R correctly explains A.
This question belongs to: Science Biology
Question #1625
Identify the INCORRECT statement about the human body:
A. The liver is the largest gland.
B. The skin is the largest organ.
C. The femur is the longest bone.
D. The heart is located on the right side of the chest.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The heart is situated in the mediastinum slightly left of the midline. All other statements are true.
This question belongs to: Science Biology
Question #1626
Consider the following statements about the blood:
1. Plasma is about 55% of blood volume.
2. Albumin is the most abundant plasma protein.
3. Red blood cells have nuclei in humans.
Which of the above is/are correct?
A. 1 and 3 only
B. 1 and 2 only
C. 1, 2, and 3
D. 2 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Plasma makes up ~55% of blood; albumin is the main protein. Mature human RBCs are anucleate. So 3 is incorrect.
This question belongs to: Science Biology
Question #1627
Assertion (A): Plants take in carbon dioxide and release oxygen during the day.
Reason (R): Photosynthesis produces oxygen as a byproduct.
A. Both A and R are true, and R is the correct explanation.
B. A false, R true.
C. Both A and R are true, but R is not the correct explanation.
D. A true, R false.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
During daylight, photosynthesis dominates, consuming CO₂ and releasing O₂. The oxygen comes from water splitting. R correctly explains A.
This question belongs to: Science Biology
Question #1628
Which of the following statements about the nephron is correct?
A. The collecting duct actively transports glucose.
B. Bowman’s capsule surrounds the loop of Henle.
C. Glomerular filtrate contains large proteins and cells.
D. The proximal tubule reabsorbs most of the glucose and amino acids.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Proximal convoluted tubule reabsorbs glucose, amino acids, and most water. Bowman’s capsule surrounds glomerulus; filtrate lacks proteins and cells; collecting duct concentrates urine.
This question belongs to: Science Biology
Question #1629
Identify the correct statement about genetic drift:
A. It is a non-random change in allele frequency.
B. It always leads to adaptation.
C. It can lead to loss of genetic variation.
D. It has a greater effect in large populations.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option C

Explanation:
Genetic drift is a random change in allele frequency, more pronounced in small populations, and can reduce genetic diversity. Natural selection leads to adaptation.
This question belongs to: Science Biology
Question #1630
Consider the following statements about the carbon cycle:
1. Photosynthesis removes CO₂ from the atmosphere.
2. Respiration and combustion return CO₂ to the atmosphere.
3. Decomposition releases CO₂.
Which of the above is/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 B

Explanation:
All are correct: photosynthesis fixes CO₂; respiration, combustion, and decomposition release it back, driving the carbon cycle.
This question belongs to: Science Biology
Question #1631
Assertion (A): Xylem vessels are dead at maturity.
Reason (R): Lignin deposition provides strength but blocks cytoplasm, leading to cell death.
A. A true, R false.
B. A false, R true.
C. Both A and R are true, but R is not the correct explanation.
D. Both A and R are true, and R is the correct explanation.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
Xylem tracheids and vessels develop lignified secondary walls and lose protoplasm, becoming dead tubes efficient for water conduction. R correctly explains A.
This question belongs to: Science Biology
Question #1632
Which of the following statements about hormones is correct?
A. Prolactin stimulates uterine contractions.
B. Growth hormone is secreted by the posterior pituitary.
C. Oxytocin is produced by the anterior pituitary.
D. ADH is synthesized in the hypothalamus and released from the posterior pituitary.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
ADH and oxytocin are synthesized in the hypothalamus and stored/released from the posterior pituitary. Growth hormone and prolactin are anterior pituitary hormones.
This question belongs to: Science Biology
Question #1633
Consider the following statements about the nervous system:
1. Motor neurons carry impulses from the CNS to effectors.
2. Sensory neurons carry impulses from receptors to the CNS.
3. Interneurons are found only in the peripheral nervous system.
Which of the above is/are correct?
A. 1 and 3 only
B. 1 and 2 only
C. 1, 2, and 3
D. 2 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Motor (efferent) and sensory (afferent) neurons are correctly described. Interneurons are found in the CNS, not PNS. So 3 is incorrect.
This question belongs to: Science Biology
Question #1634
Assertion (A): Fermentation produces less ATP than aerobic respiration.
Reason (R): Fermentation involves only glycolysis and does not use the Krebs cycle or electron transport chain.
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
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
Fermentation yields only 2 ATP from glycolysis, while aerobic respiration yields ~36-38. The reason correctly explains the lower yield.
This question belongs to: Science Biology
Question #1635
Which of the following statements about the human eye is correct?
A. The pupil is an opening that cannot change size.
B. The lens changes shape to focus on near or distant objects.
C. The blind spot contains a high density of cones.
D. The fovea has the highest concentration of rods.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Accommodation involves lens shape change via ciliary muscles. The blind spot lacks photoreceptors; fovea has high cone density; pupil adjusts via iris.
This question belongs to: Science Biology
Question #1636
Identify the correct statement about plant diseases:
A. Late blight of potato is caused by a bacterium.
B. Tobacco mosaic disease is caused by a virus.
C. Citrus canker is caused by a virus.
D. Black rust of wheat is caused by a bacterium.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
Tobacco mosaic is viral. Citrus canker is bacterial, late blight is an oomycete (fungus-like), black rust is fungal.
This question belongs to: Science Biology
Question #1637
Consider the following statements about biodiversity:
1. Biodiversity includes genetic, species, and ecosystem diversity.
2. Hotspots are regions with high endemism and habitat loss.
3. The Western Ghats is a biodiversity hotspot.
Which of the above is/are correct?
A. 1 and 2 only
B. 1, 2, and 3
C. 2 and 3 only
D. 1 and 3 only
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option B

Explanation:
All are correct: biodiversity has three levels; hotspots have high endemism and threat; Western Ghats is a recognized hotspot.
This question belongs to: Science Biology
Question #1638
Assertion (A): RNA is usually single-stranded.
Reason (R): RNA contains deoxyribose sugar.
A. A is true, but R is false.
B. Both A and R are true, and R is the correct explanation.
C. A is false, but R is true.
D. Both A and R are true, but R is not the correct explanation.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option A

Explanation:
RNA is typically single-stranded (A true), but it contains ribose, not deoxyribose. Deoxyribose is in DNA. Thus R is false.
This question belongs to: Science Biology
Question #1639
Which of the following statements about the human skeleton is correct?
A. The patella is a bone of the arm.
B. The tibia is a bone of the forearm.
C. The radius is located in the lower leg.
D. The clavicle is known as the collarbone.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The clavicle is the collarbone. Patella is kneecap; radius is forearm; tibia is shinbone. So B is correct.
This question belongs to: Science Biology
Question #1640
Identify the INCORRECT statement about the human lungs:
A. The left lung has two lobes.
B. The right lung has three lobes.
C. The pleura covers the lungs.
D. The diaphragm is a smooth muscle.
Discuss
Get Complete Subject PDF for Science

Correct Answer: Option D

Explanation:
The diaphragm is a skeletal muscle, not smooth muscle. All other statements are 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.