80 marks · 3 hours · 43 questions · NIOS board pattern · PE lessons only
Diversity, structure & plant physiology
43 Q · 80 marks
Reproduction, genetics & molecular
43 Q · 80 marks
Health, ecology, biotech & immunity
43 Q · 80 marks
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Q1. Cyanobacteria are placed in Monera mainly because they are:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Prokaryotic cell organisation places cyanobacteria in Monera.
Q2. Cephalothorax is a feature of phylum:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Many arthropods have fused head + thorax (cephalothorax).
Q3. The living component of xylem is:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Xylem parenchyma remains living; vessels/tracheids/fibres are dead at maturity.
Q4. Respiratory roots of mangroves are called:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Pneumatophores grow upward for O2 in waterlogged soil.
Q5. Potato is an example of:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Potato is a swollen underground stem (tuber) with buds (eyes).
Q6. The pink protein in legume nodules is:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Leghaemoglobin buffers O2 and protects nitrogenase.
Q7. In C4 plants the first CO2 acceptor is:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: PEP accepts CO2 in mesophyll forming OAA (4C).
Q8. Net products of glycolysis (one glucose) are typically:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Glycolysis in cytosol nets 2 ATP, 2 NADH and 2 pyruvate.
Q9. Plasma protein forming the clot mesh is:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Fibrinogen → fibrin threads form the clot.
Q10. Excess thyroxine causes:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Hyperthyroidism = oversecretion of thyroxine.
Q11. Double fertilisation produces endosperm that is usually:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Male gamete + polar nuclei → primary endosperm nucleus (3n).
Q12. Amniocentesis is used to:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Amniotic fluid sample helps detect chromosomal/genetic disorders.
Q13. F1 crossed with homozygous recessive is a:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Test cross reveals genotype of dominant phenotype.
Q14. DNA → mRNA is called:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Transcription = synthesis of RNA on DNA template.
Q15. In grass → insect → frog, frog is at trophic level:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Producers=1, herbivores=2, frog (secondary consumer)=3.
Q16. Iron overload disease is:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Excess iron deposits as hemosiderosis.
Q17. True or False: Fungi have chitinous cell walls and are typically heterotrophic.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — fungal walls contain chitin; nutrition is absorptive heterotrophy.
Q18. True or False: O2 released in photosynthesis comes mainly from CO2.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: False — O2 comes from photolysis of water, not CO2.
Q19. True or False: Lymph returns tissue fluid to the blood circulation.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — lymph vessels return fluid (and fats) to veins.
Q20. True or False: The spleen is the largest lymphoid organ in humans.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — spleen is the largest lymphoid organ.
Q21. True or False: Lactobacillus is used in setting milk into yoghurt.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — lactic acid bacteria set milk to curd/yoghurt.
Q22. True or False: Incomplete dominance in Mirabilis gives F2 phenotypic ratio 3:1.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: False — incomplete dominance gives 1:2:1 (red:pink:white).
Q23. True or False: Monoecious plants bear male and female flowers on the same plant.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — monoecious = both sexes on one plant.
Q24. True or False: Rhizobium fixes atmospheric nitrogen in free soil without hosts always.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: False — classic Rhizobium is symbiotic in legume nodules (not free-living like Azotobacter).
Q25. True or False: Kwashiorkor typically shows oedema; marasmus shows severe wasting without oedema.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — oedema marks kwashiorkor; marasmus is pure wasting.
Q26. True or False: DNA polymerase synthesises new DNA only in the 5′→3′ direction.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — polymerase adds nucleotides only 5′ to 3′.
Q27. True or False: The axon conducts impulses toward the cell body.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: False — axon carries impulses away from the cell body.
Q28. True or False: Decomposers form the final trophic role recycling nutrients.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — decomposers break down dead matter and recycle minerals.
Q29. Define meristem. Name locations of apical and lateral meristems.
Suggested length: up to 45 words · 2 marks
0 / 45 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Meristems are permanently dividing tissues. Apical: root/shoot tips (primary growth). Lateral: cambium (secondary growth/girth).
Q30. Name two proteins important in root nodules for nitrogen fixation.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Nitrogenase reduces N2 to NH3; leghaemoglobin buffers O2 protecting nitrogenase.
Q31. State the overall balanced equation of photosynthesis (as in NIOS notes).
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: 6CO2 + 12H2O → C6H12O6 + 6H2O + 6O2 (chlorophyll, light).
Q32. Name the three major phases of glycolysis and the cell site.
Suggested length: up to 45 words · 2 marks
0 / 45 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Energy investment, cleavage, energy payoff; occurs in cytosol; nets 2 ATP + 2 NADH + 2 pyruvate.
Q33. Define double fertilisation and name its two products.
Suggested length: up to 45 words · 2 marks
0 / 45 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: One male gamete + egg → zygote (2n); other + polar nuclei → endosperm (3n). Unique to angiosperms.
Q34. Name one permanent female surgical contraceptive method and its action.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Tubectomy: fallopian tubes cut/tied so ovum cannot meet sperm — permanent sterilisation.
Q35. What is a test cross? Why use homozygous recessive parent?
Suggested length: up to 45 words · 2 marks
0 / 45 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Dominant phenotype × homozygous recessive reveals genotype (Tt vs TT) from offspring ratios.
Q36. Name the largest lymphoid organ and one function.
Suggested length: up to 35 words · 2 marks
0 / 35 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Spleen — largest lymphoid organ; filters blood and supports immune responses.
Q37. Name the bacterium and plasmid used to make many transgenic plants.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Agrobacterium tumefaciens carries Ti plasmid used to insert foreign genes into plants.
Q38. Explain why a green leaf evolves O2 by day but may take up O2 at night.
Suggested length: up to 70 words · 3 marks
0 / 70 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: Day: water photolysis in chloroplasts releases O2. Night: no light reaction; cells respire sugar in mitochondria and consume O2 for ATP.
Q39. Differentiate blood and lymph (composition and path).
Suggested length: up to 70 words · 3 marks
0 / 70 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: Blood has RBCs/platelets in closed circuit heart–arteries–capillaries–veins. Lymph is pale fluid rich in lymphocytes, one-way return of tissue fluid/fats to veins.
Q40. Compare effects of excess GH in childhood with excess thyroxine in adults.
Suggested length: up to 70 words · 3 marks
0 / 70 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: Excess GH (anterior pituitary) in child → gigantism. Excess thyroxine → hyperthyroidism (high BMR, weight loss). Different glands and effects.
Q41. Distinguish marasmus and kwashiorkor with one feature each.
Suggested length: up to 65 words · 3 marks
0 / 65 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: Marasmus: severe energy+protein lack, extreme wasting, no oedema. Kwashiorkor: protein lack after weaning, oedema, moon face.
Q42. Describe how a legume obtains usable nitrogen and carbon skeletons for amino acids.
Suggested length: up to 110 words · 5 marks
0 / 110 words
How to approach: Plan 80–120 words: statement → labelled points/steps → explanation → conclusion.
NIOS marking: 5 marks = clear statement (1) + ordered points (1) + detailed explanation (2) + conclusion (1).
Example: Example: Outline N-fixation path from N2 to amino acids with Rhizobium and photosynthesis carbon.
Common mistakes: Only definition; no steps; missing conclusion.
Model answer: Rhizobium nitrogenase fixes N2→NH3 (O2 buffered by leghaemoglobin). Photosynthesis provides sugars; carbon skeletons + NH3 form amino acids/proteins.
Q43. Outline recombinant DNA tools and how bacteria can produce a human protein such as insulin.
Suggested length: up to 110 words · 5 marks
0 / 110 words
How to approach: Plan 80–120 words: statement → labelled points/steps → explanation → conclusion.
NIOS marking: 5 marks = clear statement (1) + ordered points (1) + detailed explanation (2) + conclusion (1).
Example: Example: Outline N-fixation path from N2 to amino acids with Rhizobium and photosynthesis carbon.
Common mistakes: Only definition; no steps; missing conclusion.
Model answer: Cut gene and plasmid with restriction enzyme, join with ligase, transform host; bacteria transcribe/translate the gene to make the protein (e.g. insulin).
Q1. Both male and female flowers on the same plant means the plant is:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Monoecious = both sexes on one plant.
Q2. Edible coconut kernel/water is mainly:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Coconut water/meat are endosperm.
Q3. A permanent male sterilisation method is:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Vasectomy cuts/ties vas deferens.
Q4. Dihybrid F2 phenotypic ratio under independent assortment is:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Two traits segregate independently → 9:3:3:1.
Q5. Okazaki fragments are joined by:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Ligase seals nicks between Okazaki fragments.
Q6. In lac operon, RNA polymerase binds at the:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Promoter is the RNA polymerase binding site.
Q7. Closed flowers that force self-pollination show:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Cleistogamy = flowers remain closed → selfing.
Q8. Night blindness is due to deficiency of:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Vitamin A deficiency → night blindness.
Q9. Humoral immunity is mainly mediated by:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: B cells → plasma cells → antibodies = humoral immunity.
Q10. Recombinant hepatitis B vaccine is an example of:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: rDNA produces antigen protein for hepatitis B vaccine.
Q11. Four nutrition modes of bacteria include photoautotroph and:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Bacteria: photo/chemo × auto/hetero combinations.
Q12. Fern gametophyte is the:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Heart-shaped prothallus is the gametophyte.
Q13. Bulliform cells in monocot leaves help in:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Bulliform (motor) cells change turgor → leaf rolling.
Q14. Reaction centre of PSII is approximately:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: PSII reaction centre ~P680; PSI ~P700.
Q15. Growth hormone excess in childhood may cause:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Excess GH before epiphyseal closure → gigantism.
Q16. Glycolysis occurs in the:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Glycolysis is cytosolic.
Q17. True or False: Hypanthodium is seen in Ficus (peepal/fig).
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — hypanthodium is the fig-type closed receptacle.
Q18. True or False: Fertilisation in humans normally occurs in the uterus cavity first.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: False — fertilisation normally in fallopian tube; implantation in uterus.
Q19. True or False: Haemophilia is typically X-linked recessive.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — classic haemophilia is X-linked recessive.
Q20. True or False: Translation occurs on ribosomes.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — mRNA is translated on ribosomes to protein.
Q21. True or False: Primary succession starts on bare rock without prior soil.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — primary succession begins on bare substrate.
Q22. True or False: Fat gives about 9 kcal per gram, more than carbohydrate.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — fat ~9 kcal/g vs carb/protein ~4 kcal/g.
Q23. True or False: IgG is the most abundant serum immunoglobulin.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — IgG is about three-quarters of serum Ig.
Q24. True or False: Restriction enzymes are called molecular scissors.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — they cut DNA at specific sites.
Q25. True or False: Crocodiles among reptiles have a four-chambered heart.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — crocodilians have four chambers.
Q26. True or False: Nitrogenase is oxygen-sensitive.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — free O2 inactivates nitrogenase; hence leghaemoglobin helps.
Q27. True or False: Onion bulb is a root modification.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: False — bulb is a stem modification with fleshy scales.
Q28. True or False: Velamen helps epiphyte aerial roots absorb moisture.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — multilayered velamen absorbs atmospheric moisture.
Q29. State F2 phenotypic ratio for incomplete dominance in Mirabilis.
Suggested length: up to 35 words · 2 marks
0 / 35 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: 1 red : 2 pink : 1 white (incomplete dominance).
Q30. Correct the wrong central dogma sequence DNA → protein by replication.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Replication is DNA→DNA; DNA→RNA is transcription; RNA→protein is translation.
Q31. List three effects of uncontrolled population growth.
Suggested length: up to 45 words · 2 marks
0 / 45 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Unemployment, pressure on food/housing/schools/health, environmental degradation, poverty.
Q32. Define ecotone with one example.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Ecotone is a transition zone between two ecosystems (e.g. wetland edge).
Q33. State functions of B-cells and T-cells in one line each.
Suggested length: up to 45 words · 2 marks
0 / 45 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: B-cells: antibodies/plasma cells (humoral). T-cells: help/kill (cell-mediated), mature in thymus.
Q34. Name two types of endosperm.
Suggested length: up to 30 words · 2 marks
0 / 30 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Nuclear, cellular and helobial endosperm (any two).
Q35. Name fat-soluble and water-soluble vitamin classes with one example each.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Fat-soluble A,D,E,K (e.g. A); water-soluble B-complex and C (e.g. C).
Q36. Name the clotting plasma protein and its product.
Suggested length: up to 35 words · 2 marks
0 / 35 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Fibrinogen is converted to fibrin, which forms the clot mesh.
Q37. Where do light and dark reactions of photosynthesis occur?
Suggested length: up to 35 words · 2 marks
0 / 35 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Light reaction: thylakoid membranes; dark/Calvin: stroma of chloroplast.
Q38. Explain how a gene for flower pigment can produce incomplete dominance phenotype.
Suggested length: up to 75 words · 3 marks
0 / 75 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: DNA gene → mRNA → enzyme → pigment. One functional allele in heterozygote yields intermediate (pink) colour — incomplete dominance.
Q39. Outline sperm path labels: acrosome and mitochondria functions.
Suggested length: up to 65 words · 3 marks
0 / 65 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: Acrosome enzymes help penetrate egg coats; midpiece mitochondria supply ATP for tail motility.
Q40. Why are food chains usually short? Mention energy transfer idea.
Suggested length: up to 70 words · 3 marks
0 / 70 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: Only a fraction (~10%) of energy passes each level; rest lost as heat via metabolism — limited energy for many levels.
Q41. List steps of recombinant DNA technology in order (tools).
Suggested length: up to 70 words · 3 marks
0 / 70 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: Cut DNA with restriction enzyme → insert into plasmid with ligase → transform host → clone/amplify recombinant DNA.
Q42. Connect double fertilisation, human fertilisation site, and a monohybrid test cross purpose.
Suggested length: up to 120 words · 5 marks
0 / 120 words
How to approach: Plan 80–120 words: statement → labelled points/steps → explanation → conclusion.
NIOS marking: 5 marks = clear statement (1) + ordered points (1) + detailed explanation (2) + conclusion (1).
Example: Example: Outline N-fixation path from N2 to amino acids with Rhizobium and photosynthesis carbon.
Common mistakes: Only definition; no steps; missing conclusion.
Model answer: Angiosperm seed: zygote+endosperm from double fertilisation. Human: fertilisation in oviduct, implant uterus. Test cross with recessive parent finds if dominant plant is hetero/homozygous.
Q43. Explain antibody structure labels and how vaccination creates memory (link to antigen).
Suggested length: up to 120 words · 5 marks
0 / 120 words
How to approach: Plan 80–120 words: statement → labelled points/steps → explanation → conclusion.
NIOS marking: 5 marks = clear statement (1) + ordered points (1) + detailed explanation (2) + conclusion (1).
Example: Example: Outline N-fixation path from N2 to amino acids with Rhizobium and photosynthesis carbon.
Common mistakes: Only definition; no steps; missing conclusion.
Model answer: Antibody Y: two heavy+two light chains; antigen-binding sites on arms; Fc stem. Vaccine antigen trains B/T cells → memory for faster response later.
Q1. Body-building foods are mainly rich in:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Proteins build tissues — body-building foods.
Q2. Goitre is commonly linked to deficiency of:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Iodine deficiency → goitre.
Q3. Cells in lymph nodes that attack pathogens include:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Lymphocytes (B and T) populate lymph nodes.
Q4. Molecular glue joining DNA fragments is:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Ligase joins sticky ends — molecular glue.
Q5. Final trophic role recycling dead matter is played by:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Decomposers mineralise dead organic matter.
Q6. ADH is released from the:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: ADH is released by posterior pituitary (made in hypothalamus).
Q7. Open vs closed circulation differs in that closed systems have:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Closed circulation keeps blood in vessels.
Q8. Calvin cycle occurs in the:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Calvin (dark) reactions in chloroplast stroma.
Q9. Complete aerobic oxidation of glucose yields about:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Aerobic respiration yields ~36–38 ATP per glucose (textbook).
Q10. Free-living aerobic nitrogen fixer example:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Azotobacter is free-living aerobic N2 fixer.
Q11. Tap root system is typical of:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Dicots commonly have a main tap root with laterals.
Q12. Oviparous mammal example:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Platypus is an egg-laying monotreme mammal.
Q13. Mushroom gills are associated with production of:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Gills bear basidia producing spores.
Q14. Tapetum in anther nourishes:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Innermost tapetum nourishes pollen.
Q15. Copper-T mainly acts as:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: IUD such as Copper-T interferes with implantation/uterine environment.
Q16. Colour blindness is typically:
How to approach: Read all four options. Eliminate wrong definitions or organisms. Choose the option that matches NIOS Biology notes.
NIOS marking: 1 mark all-or-nothing for the correct option. No partial credit on MCQ.
Example: Example: C4 first CO2 acceptor is PEP (not RuBP).
Common mistakes: Confusing similar terms (marasmus vs kwashiorkor; monoecious vs dioecious; transcription vs translation).
Model answer: Red-green colour blindness is classically X-linked.
Q17. True or False: Balanced diet supplies all nutrients in right amounts and proportions.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — balanced diet meets nutrient needs in correct proportion.
Q18. True or False: Innate immunity includes barriers, phagocytes and complement.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — physical barriers, phagocytes and complement are innate.
Q19. True or False: Fermentation by yeast can produce ethanol and CO2.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — alcoholic fermentation yields ethanol + CO2.
Q20. True or False: Mutualism benefits both interacting species.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — mutualism is +/+ interaction.
Q21. True or False: AUG is a common start codon.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — AUG codes methionine and starts translation.
Q22. True or False: Insulin lowers blood glucose.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — insulin promotes glucose uptake/use, lowering blood sugar.
Q23. True or False: Arteries always carry only deoxygenated blood.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: False — pulmonary artery carries deoxygenated blood; most arteries carry oxygenated blood.
Q24. True or False: Krebs cycle occurs in the mitochondrial matrix.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — TCA/Krebs is in mitochondrial matrix.
Q25. True or False: Accessory pigments pass energy to chlorophyll a.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — carotenoids/Chl-b transfer energy to reaction-centre Chl-a.
Q26. True or False: Phylloclade is a stem modified for photosynthesis.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — flattened green stem (e.g. Opuntia) photosynthesises.
Q27. True or False: Meristematic cells usually have large central vacuoles.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: False — meristem cells have dense cytoplasm and small/no large vacuoles.
Q28. True or False: Photoautotrophic bacteria use light and CO2.
How to approach: Answer True/False carefully or fill blanks in 25–35 words. State the fact and one short reason.
NIOS marking: 2 marks = correct statement (1) + brief reason/example (1).
Example: Example: True — spleen is the largest lymphoid organ; it filters blood and stores immune cells.
Common mistakes: Guessing without reason; mixing plant and human examples.
Model answer: True — photoautotrophs: light energy + inorganic carbon.
Q29. Define obesity and give one cause and one health risk.
Suggested length: up to 45 words · 2 marks
0 / 45 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Obesity = excess body fat from energy surplus. Causes: overeating, low exercise. Risks: CVD, diabetes.
Q30. What is an antigen? Name the antibody site that binds it.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Antigen is foreign molecule triggering immune response; antibody antigen-binding site (paratope) binds epitope.
Q31. Define antibiotic and name one fungal source example.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Antibiotic is microbe-made substance inhibiting another microbe; e.g. penicillin from Penicillium.
Q32. Define population in ecology.
Suggested length: up to 35 words · 2 marks
0 / 35 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Population = individuals of same species in a given area at a given time.
Q33. Name the three processes of central dogma with direction.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Replication DNA→DNA; transcription DNA→RNA; translation RNA→protein.
Q34. State Mendel’s law of segregation in one sentence.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: The two alleles of a gene separate into different gametes during meiosis.
Q35. What is a monoecious plant? Give one crop example idea.
Suggested length: up to 35 words · 2 marks
0 / 35 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Male and female flowers on same plant (e.g. maize).
Q36. Name hormones STH and TSH with source gland.
Suggested length: up to 40 words · 2 marks
0 / 40 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: STH = growth hormone (anterior pituitary); TSH = thyroid-stimulating hormone (anterior pituitary).
Q37. State one difference between artery and vein walls/lumen.
Suggested length: up to 35 words · 2 marks
0 / 35 words
How to approach: Write 30–50 words. Open with definition/name, then one-line function or example.
NIOS marking: 2 marks = correct term/definition (1) + brief explanation (1).
Example: Example: Leghaemoglobin is the pink O2-buffer in nodules that protects nitrogenase.
Common mistakes: Long essay; missing key term; wrong organ/site.
Model answer: Arteries: thick elastic walls, narrow lumen, high pressure; veins: thinner walls, wider lumen, valves.
Q38. How can rapid population growth increase PEM risk? Link food access and child nutrition.
Suggested length: up to 75 words · 3 marks
0 / 75 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: More people strain food supply and poverty; young children on poor weaning diets risk marasmus/kwashiorkor PEM.
Q39. How does a recombinant vaccine train immunity without whole pathogen?
Suggested length: up to 70 words · 3 marks
0 / 70 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: rDNA makes pure antigen protein; immune system makes antibodies and memory cells without live disease organism.
Q40. Trace energy from sunlight to a secondary consumer in one sentence chain with process names.
Suggested length: up to 70 words · 3 marks
0 / 70 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: Sunlight → photosynthesis in producers → eaten by herbivores (primary consumers) → secondary consumers; energy drops each trophic step.
Q41. Why is glucose important for both plant respiration and human CNS fuel idea in notes context?
Suggested length: up to 70 words · 3 marks
0 / 70 words
How to approach: Structure: definition (1) → process/mechanism (1) → example or conclusion (1). About 50–80 words.
NIOS marking: 3 marks = key idea (1) + reasoning (1) + example/conclusion (1).
Example: Example: Double fertilisation → zygote (2n) + endosperm (3n); unique to angiosperms.
Common mistakes: Skipping mechanism; no example; wrong sequence.
Model answer: Respiration oxidises glucose to ATP for work. Notes also stress glucose as essential fuel for CNS — energy currency links both.
Q42. Explain primary succession starting with cyanobacteria and ending in forest, naming kingdoms of pioneers.
Suggested length: up to 120 words · 5 marks
0 / 120 words
How to approach: Plan 80–120 words: statement → labelled points/steps → explanation → conclusion.
NIOS marking: 5 marks = clear statement (1) + ordered points (1) + detailed explanation (2) + conclusion (1).
Example: Example: Outline N-fixation path from N2 to amino acids with Rhizobium and photosynthesis carbon.
Common mistakes: Only definition; no steps; missing conclusion.
Model answer: Primary succession: bare rock → cyanobacteria (Monera) and lichens → mosses → shrubs → trees (climax). Pioneers are prokaryotes/simple organisms building soil for later plants (Plantae).
Q43. Write an integrated note: how plants make sugar, release energy, and how humans need that energy plus proteins (N) for health.
Suggested length: up to 120 words · 5 marks
0 / 120 words
How to approach: Plan 80–120 words: statement → labelled points/steps → explanation → conclusion.
NIOS marking: 5 marks = clear statement (1) + ordered points (1) + detailed explanation (2) + conclusion (1).
Example: Example: Outline N-fixation path from N2 to amino acids with Rhizobium and photosynthesis carbon.
Common mistakes: Only definition; no steps; missing conclusion.
Model answer: Photosynthesis makes glucose; respiration yields ATP. Proteins need N (plants get via fixation/soil N). Humans need energy foods + body-building proteins in balanced diet to avoid PEM and deficiency disease.