50 MCQ on Biology for NEET and CSIR EXAM Part -2

1. Which enzyme is responsible for unwinding DNA during replication?
   A. DNA polymerase
   B. Helicase
   C. Ligase
   D. Topoisomerase
   Answer: B

2. The Okazaki fragments are formed during:
   A. Leading strand synthesis
   B. Lagging strand synthesis
   C. RNA transcription
   D. DNA repair
   Answer: B

3. Which part of chloroplast is the site of Calvin cycle?
   A. Thylakoid membrane
   B. Thylakoid lumen
   C. Stroma
   D. Granum
   Answer: C

4. Which enzyme catalyzes the fixation of CO₂ in C3 plants?
   A. PEP carboxylase
   B. RuBisCO
   C. ATP synthase
   D. NADP reductase
   Answer: B

5. In C4 plants, the first stable product of CO₂ fixation is:
   A. Pyruvate
   B. Oxaloacetic acid
   C. Malate
   D. Phosphoglyceric acid
   Answer: B

6. Which hormone induces cell elongation in plants?
   A. Cytokinin
   B. Auxin
   C. Ethylene
   D. Abscisic acid
   Answer: B

7. The genetic code is said to be degenerate because:
   A. Codons overlap
   B. One codon codes for multiple amino acids
   C. Multiple codons code for one amino acid
   D. Codons are continuous
   Answer: C

8. Which stage of meiosis involves crossing over?
   A. Leptotene
   B. Zygotene
   C. Pachytene
   D. Diplotene
   Answer: C

9. The Hardy–Weinberg equilibrium describes:
   A. Mutation frequency
   B. Genetic drift
   C. Allele frequency in a population
   D. Gene linkage
   Answer: C

10. Which structure forms the spindle fibers during cell division?
    A. Ribosome
    B. Centriole
    C. Lysosome
    D. Golgi apparatus
    Answer: B

11. Photorespiration mainly occurs in:
    A. C4 plants
    B. CAM plants
    C. C3 plants
    D. All plants equally
    Answer: C

12. Which enzyme converts RNA into DNA?
    A. RNA polymerase
    B. DNA ligase
    C. Reverse transcriptase
    D. Primase
    Answer: C

13. The light reaction of photosynthesis occurs in:
    A. Stroma
    B. Thylakoid membrane
    C. Matrix
    D. Cytoplasm
    Answer: B

14. Which molecule carries amino acids to ribosome?
    A. mRNA
    B. rRNA
    C. tRNA
    D. snRNA
    Answer: C

15. The lac operon is an example of:
    A. Gene repression
    B. Gene regulation
    C. Mutation
    D. DNA repair
    Answer: B

16. Which blood cells act as phagocytes?
    A. RBC
    B. Platelets
    C. Neutrophils
    D. Erythrocytes
    Answer: C

17. Which component of blood helps in immune response?
    A. RBC
    B. WBC
    C. Platelets
    D. Plasma proteins only
    Answer: B

18. Which hormone stimulates ovulation?
    A. FSH
    B. LH
    C. Prolactin
    D. Progesterone
    Answer: B

19. Which nitrogenous base pairs with guanine in DNA?
    A. Adenine
    B. Cytosine
    C. Thymine
    D. Uracil
    Answer: B

20. The Krebs cycle occurs in:
    A. Cytoplasm
    B. Mitochondrial matrix
    C. Nucleus
    D. Ribosome
    Answer: B

21. Which structure increases surface area for absorption in small intestine?
    A. Alveoli
    B. Villi
    C. Nephrons
    D. Glomeruli
    Answer: B

22. The oxygen dissociation curve of hemoglobin shifts right due to:
    A. Increased pH
    B. Decreased CO₂
    C. Increased temperature
    D. Decreased temperature
    Answer: C

23. Which organelle is responsible for intracellular digestion?
    A. Golgi apparatus
    B. Lysosome
    C. Ribosome
    D. Nucleus
    Answer: B

24. Which stage of mitosis shows chromosome alignment at equator?
    A. Prophase
    B. Metaphase
    C. Anaphase
    D. Telophase
    Answer: B

25. Which vitamin is essential for blood clotting?
    A. Vitamin A
    B. Vitamin K
    C. Vitamin C
    D. Vitamin D
    Answer: B

26. The functional unit of muscle contraction is:
    A. Myofibril
    B. Sarcomere
    C. Actin
    D. Myosin
    Answer: B

27. Which structure of nephron performs filtration?
    A. Loop of Henle
    B. Distal tubule
    C. Glomerulus
    D. Collecting duct
    Answer: C

28. Which hormone increases heart rate during stress?
    A. Insulin
    B. Adrenaline
    C. Thyroxine
    D. Melatonin
    Answer: B

29. Which plant hormone promotes fruit ripening?
    A. Auxin
    B. Ethylene
    C. Cytokinin
    D. Gibberellin
    Answer: B

30. Which molecule stores genetic information in viruses like HIV?
    A. DNA
    B. RNA
    C. Protein
    D. Lipid
    Answer: B

31. Which tissue conducts water in plants?
    A. Phloem
    B. Xylem
    C. Cambium
    D. Epidermis
    Answer: B

32. Which process produces genetically identical cells?
    A. Meiosis
    B. Mitosis
    C. Fertilization
    D. Recombination
    Answer: B

33. Which organelle modifies proteins after synthesis?
    A. Ribosome
    B. Golgi apparatus
    C. Lysosome
    D. Peroxisome
    Answer: B

34. Which disease is caused by Plasmodium?
    A. Dengue
    B. Malaria
    C. Typhoid
    D. Tuberculosis
    Answer: B

35. Which component forms the cell membrane bilayer?
    A. Carbohydrates
    B. Phospholipids
    C. Proteins
    D. Nucleic acids
    Answer: B

36. Which process forms gametes in humans?
    A. Mitosis
    B. Meiosis
    C. Binary fission
    D. Budding
    Answer: B

37. Which blood vessel carries oxygenated blood from lungs to heart?
    A. Pulmonary artery
    B. Pulmonary vein
    C. Aorta
    D. Vena cava
    Answer: B

38. Which gland secretes insulin?
    A. Thyroid
    B. Pancreas
    C. Pituitary
    D. Adrenal
    Answer: B

39. Which process converts nitrogen gas into ammonia biologically?
    A. Nitrification
    B. Nitrogen fixation
    C. Ammonification
    D. Denitrification
    Answer: B

40. Which pigment participates directly in light reaction of photosynthesis?
    A. Chlorophyll a
    B. Chlorophyll b
    C. Carotene
    D. Xanthophyll
    Answer: A

41. Which part of neuron receives signals?
    A. Axon
    B. Dendrite
    C. Synapse
    D. Myelin sheath
    Answer: B

42. Which stage of meiosis separates homologous chromosomes?
    A. Anaphase I
    B. Anaphase II
    C. Metaphase I
    D. Telophase II
    Answer: A

43. Which molecule acts as energy currency of the cell?
    A. ADP
    B. ATP
    C. AMP
    D. NADH
    Answer: B

44. Which organ stores bile?
    A. Liver
    B. Pancreas
    C. Gall bladder
    D. Stomach
    Answer: C

45. Which process produces ATP in mitochondria using oxygen?
    A. Glycolysis
    B. Oxidative phosphorylation
    C. Fermentation
    D. Photophosphorylation
    Answer: B

46. Which ecological pyramid is always upright?
    A. Pyramid of biomass
    B. Pyramid of energy
    C. Pyramid of numbers
    D. All pyramids
    Answer: B

47. Which structure in plants controls stomatal opening?
    A. Guard cells
    B. Mesophyll cells
    C. Xylem cells
    D. Cortex cells
    Answer: A

48. Which organelle contains digestive enzymes?
    A. Golgi body
    B. Lysosome
    C. Ribosome
    D. Centriole
    Answer: B

49. Which hormone maintains pregnancy?
    A. Estrogen
    B. Progesterone
    C. Oxytocin
    D. FSH
    Answer: B

50. Which process results in variation during meiosis?
    A. Crossing over
    B. DNA replication
    C. Transcription
    D. Translation
    Answer: A