Botany MCQs (Part 1: Q1–25)

Important for CBSE/State Boards, NEET, CUET, CSIR-NET, GATE, Medical Entrances & Olympiads

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Q1. The term “Botany” is derived from:

A. Latin word Biota
Explanation: Incorrect. Biota refers to life collectively.

B. Greek word Botane
Answer: Correct. Botane means herbs/plant, origin of Botany.

C. French word Bota
Explanation: Incorrect. Not French in origin.

D. Sanskrit word Vatika
Explanation: Incorrect. Although Sanskrit has terms, Botany derives from Greek.

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Q2. Photosynthesis mainly occurs in which cell organelle?

A. Mitochondria
Explanation: Incorrect. Mitochondria are for respiration.

B. Chloroplast
Answer: Correct. Chloroplast contains chlorophyll for photosynthesis.

C. Nucleus
Explanation: Incorrect. Nucleus controls genetic material.

D. Ribosome
Explanation: Incorrect. Ribosomes synthesize proteins, not photosynthesis.

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Q3. The first stable product of C3 cycle is:

A. Oxaloacetic acid
Explanation: Incorrect. This is first product of C4 cycle.

B. 3-phosphoglycerate (3-PGA)
Answer: Correct. First stable product of Calvin cycle.

C. Malic acid
Explanation: Incorrect. Malic acid forms in CAM pathway.

D. Pyruvic acid
Explanation: Incorrect. Not first product in C3 cycle.

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Q4. Which plant tissue is responsible for transport of water?

A. Phloem
Explanation: Incorrect. Phloem transports food.

B. Xylem
Answer: Correct. Xylem conducts water and minerals.

C. Parenchyma
Explanation: Incorrect. Parenchyma is for storage and photosynthesis.

D. Collenchyma
Explanation: Incorrect. Provides mechanical support.

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Q5. Guard cells regulate:

A. Transpiration and gaseous exchange
Explanation: Correct, but not specific to other functions.

B. Opening and closing of stomata
Answer: Correct. Guard cells control stomatal aperture.

C. Food conduction
Explanation: Incorrect. Phloem conducts food.

D. Root absorption
Explanation: Incorrect. Roots absorb water, not guard cells.

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Q6. CAM plants open their stomata:

A. During day
Explanation: Incorrect. Daytime stomata mostly closed.

B. During night
Answer: Correct. CAM plants open stomata at night to reduce water loss.

C. Always closed
Explanation: Incorrect. They do open but at night.

D. Randomly
Explanation: Incorrect. There is a fixed rhythm.

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Q7. Plant hormone responsible for cell elongation is:

A. Cytokinin
Explanation: Incorrect. Promotes cell division.

B. Auxin
Answer: Correct. Indole-3-acetic acid stimulates elongation.

C. Abscisic acid
Explanation: Incorrect. Inhibits growth.

D. Ethylene
Explanation: Incorrect. Promotes fruit ripening, not elongation.

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Q8. The cork cells in plants are dead due to:

A. Lignin deposition
Explanation: Incorrect. Lignin is in xylem.

B. Suberin deposition
Answer: Correct. Suberin makes cork impermeable.

C. Pectin deposition
Explanation: Incorrect. Pectin occurs in middle lamella.

D. Cellulose thickening
Explanation: Incorrect. Cellulose does not cause death.

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Q9. The process of loss of water in liquid form from leaf margins is called:

A. Transpiration
Explanation: Incorrect. Transpiration is vapor loss.

B. Guttation
Answer: Correct. Water oozes out at leaf tips through hydathodes.

C. Bleeding
Explanation: Incorrect. Bleeding occurs from injured parts.

D. Perspiration
Explanation: Incorrect. Used in animals, not plants.

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Q10. Which of the following is a C4 plant?

A. Wheat
Explanation: Incorrect. Wheat is C3.

B. Maize
Answer: Correct. Maize has Kranz anatomy and C4 pathway.

C. Rice
Explanation: Incorrect. Rice is C3.

D. Potato
Explanation: Incorrect. Potato is C3 plant.

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Q11. The smallest living unit of a plant is:

A. Tissue
Explanation: Incorrect. Tissue is a group of cells.

B. Cell
Answer: Correct. Cell is the structural and functional unit.

C. Organelle
Explanation: Incorrect. Organelle is sub-cellular.

D. Gene
Explanation: Incorrect. Gene is hereditary unit, not structural unit.

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Q12. Double fertilization is a unique feature of:

A. Gymnosperms
Explanation: Incorrect. They lack double fertilization.

B. Angiosperms
Answer: Correct. One sperm fertilizes egg, another forms endosperm.

C. Bryophytes
Explanation: Incorrect. Fertilization is different.

D. Pteridophytes
Explanation: Incorrect. They do not show double fertilization.

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Q13. Which pigment is essential for photolysis of water?

A. Chlorophyll b
Explanation: Incorrect. Accessory pigment.

B. Chlorophyll a
Answer: Correct. Reaction center pigment in photosystem II.

C. Carotene
Explanation: Incorrect. Accessory pigment.

D. Xanthophyll
Explanation: Incorrect. Accessory pigment.

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Q14. Which of the following is a non-essential element for plants?

A. Nitrogen
Explanation: Incorrect. Essential macronutrient.

B. Sodium
Answer: Correct. Beneficial but not essential for all plants.

C. Potassium
Explanation: Incorrect. Essential macronutrient.

D. Iron
Explanation: Incorrect. Essential micronutrient.

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Q15. Leghemoglobin in root nodules helps in:

A. Nitrogen fixation
Explanation: Indirect, but not the direct mechanism.

B. Oxygen scavenging
Answer: Correct. Maintains anaerobic conditions for nitrogenase.

C. ATP production
Explanation: Incorrect. Respiration makes ATP.

D. Protein synthesis
Explanation: Incorrect. Ribosomes make proteins.

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Q16. The first stable product of C4 cycle is:

A. 3-PGA
Explanation: Incorrect. Found in C3.

B. Oxaloacetic acid (OAA)
Answer: Correct. Four-carbon OAA is first product.

C. Malic acid
Explanation: Incorrect. OAA is converted to malate.

D. Pyruvate
Explanation: Incorrect. Pyruvate is later product.

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Q17. Plants absorb nitrogen mainly in the form of:

A. N2
Explanation: Incorrect. Atmospheric N2 is unavailable.

B. Nitrate and ammonium
Answer: Correct. NO3⁻ and NH4⁺ are major forms absorbed.

C. Urea
Explanation: Incorrect. Urea must be converted first.

D. Amino acids
Explanation: Incorrect. Not directly absorbed.

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Q18. Which plant hormone induces dormancy?

A. Auxin
Explanation: Incorrect. Promotes growth.

B. Cytokinin
Explanation: Incorrect. Promotes cell division.

C. Abscisic acid (ABA)
Answer: Correct. Stress hormone inducing dormancy.

D. Gibberellin
Explanation: Incorrect. Breaks dormancy.

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Q19. Vernalization promotes:

A. Seed dormancy
Explanation: Incorrect. Dormancy is by ABA.

B. Flowering after exposure to low temperature
Answer: Correct. Vernalization induces early flowering.

C. Leaf fall
Explanation: Incorrect. Caused by ethylene/ABA.

D. Photoperiodism
Explanation: Incorrect. Controlled by light duration.

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Q20. Which is the primary CO₂ acceptor in C4 plants?

A. RuBP
Explanation: Incorrect. CO₂ acceptor in C3 cycle.

B. PEP (phosphoenolpyruvate)
Answer: Correct. CO₂ combines with PEP to form OAA.

C. Malate
Explanation: Incorrect. Malate is formed later.

D. 3-PGA
Explanation: Incorrect. Found in C3 cycle.

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Q21. Apical dominance in plants is due to:

A. Auxin in shoot apex
Answer: Correct. Auxin suppresses lateral bud growth.

B. Cytokinin in leaves
Explanation: Incorrect. Promotes division, not dominance.

C. Gibberellin in roots
Explanation: Incorrect. Promotes elongation, not dominance.

D. Ethylene in buds
Explanation: Incorrect. Not responsible for dominance.

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Q22. Which plant is called “living fossil”?

A. Pinus
Explanation: Incorrect. Gymnosperm but not living fossil.

B. Ginkgo biloba
Answer: Correct. Surviving species of ancient group.

C. Cycas
Explanation: Incorrect. Ancient, but not true living fossil.

D. Selaginella
Explanation: Incorrect. Pteridophyte, not considered living fossil.

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Q23. In which tissue does secondary growth occur?

A. Parenchyma
Explanation: Incorrect. Parenchyma has no secondary growth.

B. Vascular cambium
Answer: Correct. Responsible for secondary growth.

C. Collenchyma
Explanation: Incorrect. Provides support.

D. Xylem
Explanation: Incorrect. Product of secondary growth, not initiator.

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Q24. The first step in glycolysis is catalyzed by:

A. Phosphofructokinase
Explanation: Incorrect. Catalyzes later step.

B. Hexokinase
Answer: Correct. Phosphorylates glucose to glucose-6-phosphate.

C. Enolase
Explanation: Incorrect. Catalyzes penultimate step.

D. Aldolase
Explanation: Incorrect. Splits fructose-1,6-bisphosphate.

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Q25. Kranz anatomy is found in:

A. C3 plants
Explanation: Incorrect. Absent in C3.

B. C4 plants
Answer: Correct. Bundle sheath cells with chloroplasts are Kranz anatomy.

C. CAM plants
Explanation: Incorrect. CAM lacks Kranz.

D. Bryophytes
Explanation: Incorrect. Non-vascular plants.

Botany MCQs (Part 2: Q26–50)

Important for CBSE/State Boards, NEET, CUET, CSIR-NET, GATE, Medical Entrances & Olympiads

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Q26. The male gametophyte in angiosperms is:

A. Ovule
Explanation: Incorrect. Ovule contains female gametophyte.

B. Pollen grain
Answer: Correct. Pollen grain develops into male gametophyte.

C. Embryo sac
Explanation: Incorrect. Female gametophyte in angiosperms.

D. Endosperm
Explanation: Incorrect. Nutritive tissue after fertilization.

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Q27. The female gametophyte in angiosperms is commonly known as:

A. Pollen tube
Explanation: Incorrect. Delivers male gametes.

B. Ovary
Explanation: Incorrect. Ovary encloses ovules.

C. Embryo sac
Answer: Correct. Embryo sac contains egg apparatus.

D. Synergids
Explanation: Incorrect. Synergids are part of embryo sac.

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Q28. The ploidy of endosperm in angiosperms is:

A. Haploid
Explanation: Incorrect. Haploid cells do not form endosperm.

B. Diploid
Explanation: Incorrect. Seen in gymnosperms.

C. Triploid
Answer: Correct. Double fertilization gives triploid endosperm.

D. Tetraploid
Explanation: Incorrect. Not usual condition.

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Q29. The casparian strip is found in:

A. Phloem
Explanation: Incorrect. Found in endodermis, not phloem.

B. Endodermis
Answer: Correct. Lignin/suberin bands in radial walls regulate flow.

C. Epidermis
Explanation: Incorrect. Epidermis lacks casparian strip.

D. Pericycle
Explanation: Incorrect. Located inside endodermis.

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Q30. The function of sieve tube elements is:

A. Water conduction
Explanation: Incorrect. Xylem conducts water.

B. Food conduction
Answer: Correct. Phloem transports sucrose and organic solutes.

C. Mechanical support
Explanation: Incorrect. Sclerenchyma provides support.

D. Photosynthesis
Explanation: Incorrect. Performed by chloroplasts.

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Q31. The enzyme RuBisCO is involved in:

A. Carbon fixation in Calvin cycle
Answer: Correct. Catalyzes CO₂ fixation to RuBP.

B. Glycolysis
Explanation: Incorrect. Not part of glycolysis.

C. Photorespiration only
Explanation: Incorrect. Functions in both Calvin and photorespiration.

D. Fermentation
Explanation: Incorrect. Not role of RuBisCO.

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Q32. Stomata open due to:

A. Loss of turgor in guard cells
Explanation: Incorrect. That closes stomata.

B. Gain of turgor in guard cells
Answer: Correct. Guard cell swelling opens pore.

C. Deposition of suberin
Explanation: Incorrect. Found in cork cells.

D. ABA accumulation
Explanation: Incorrect. ABA induces closure.

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Q33. C4 plants are more efficient because:

A. They lack chloroplasts
Explanation: Incorrect. They have chloroplasts.

B. They concentrate CO₂ in bundle sheath, reducing photorespiration
Answer: Correct. Kranz anatomy enhances efficiency.

C. They absorb more nitrogen
Explanation: Incorrect. Not main factor.

D. They use less sunlight
Explanation: Incorrect. Light requirement is same or more.

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Q34. The floral formula of a typical dicot flower is:

A. ⚥ K5 C5 A5 G1
Explanation: Incorrect. Not a standard dicot example.

B. ⚥ K(5) C(5) A5 G(2-5)
Answer: Correct. Symmetry, calyx, corolla, androecium, gynoecium.

C. ⚥ K3 C3 A6 G1
Explanation: Incorrect. Typical monocot.

D. ⚥ K(3) C(3) A3 G(3)
Explanation: Incorrect. Monocot trimerous flowers.

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Q35. In Bryophytes, the dominant generation is:

A. Sporophyte
Explanation: Incorrect. Sporophyte is dependent.

B. Gametophyte
Answer: Correct. Gametophyte is dominant and photosynthetic.

C. Equal sporophyte and gametophyte
Explanation: Incorrect. Not equal.

D. No alternation of generations
Explanation: Incorrect. Bryophytes show alternation.

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Q36. Which of the following is a xerophyte adaptation?

A. Broad leaves
Explanation: Incorrect. Common in mesophytes.

B. Thick cuticle and sunken stomata
Answer: Correct. Reduce water loss.

C. Thin cuticle
Explanation: Incorrect. Seen in hydrophytes.

D. Aerenchyma
Explanation: Incorrect. Found in hydrophytes.

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Q37. Pneumatophores are found in:

A. Epiphytes
Explanation: Incorrect. Epiphytes have aerial roots.

B. Mangroves
Answer: Correct. Pneumatophores help in gaseous exchange in saline swamps.

C. Desert plants
Explanation: Incorrect. Have tap roots.

D. Climbers
Explanation: Incorrect. Use tendrils, not pneumatophores.

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Q38. Which plant tissue stores starch?

A. Collenchyma
Explanation: Incorrect. Provides support.

B. Parenchyma
Answer: Correct. Stores food, water, starch.

C. Xylem
Explanation: Incorrect. Conduction of water.

D. Phloem
Explanation: Incorrect. Transports food, does not store.

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Q39. Palisade parenchyma is specialized for:

A. Storage
Explanation: Incorrect. Storage in spongy parenchyma.

B. Photosynthesis
Answer: Correct. Palisade cells rich in chloroplasts.

C. Water transport
Explanation: Incorrect. Xylem transports water.

D. Food transport
Explanation: Incorrect. Phloem transports food.

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Q40. Corm is a modification of:

A. Root
Explanation: Incorrect. Root modification includes tuberous root.

B. Stem
Answer: Correct. Corm is a swollen underground stem (e.g., Colocasia).

C. Leaf
Explanation: Incorrect. Not a leaf modification.

D. Flower
Explanation: Incorrect. Not floral structure.

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Q41. The main function of lenticels is:

A. Water absorption
Explanation: Incorrect. Roots absorb water.

B. Gaseous exchange in woody stems
Answer: Correct. Lenticels allow O₂ and CO₂ diffusion.

C. Conduction of food
Explanation: Incorrect. Done by phloem.

D. Transport of minerals
Explanation: Incorrect. Done by xylem.

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Q42. Example of a parasitic angiosperm is:

A. Pisum
Explanation: Incorrect. Normal autotroph.

B. Cuscuta
Answer: Correct. Dodder is a total stem parasite.

C. Viscum
Explanation: Semi-parasite, not total.

D. Hibiscus
Explanation: Incorrect. Autotroph.

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Q43. Mycorrhizal association is between:

A. Plant and bacteria
Explanation: Incorrect. That is Rhizobium association.

B. Plant roots and fungi
Answer: Correct. Mycorrhiza aids in nutrient absorption.

C. Plant and algae
Explanation: Incorrect. Lichen is plant-algae/fungi.

D. Plant and protozoa
Explanation: Incorrect. Rare association.

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Q44. Which of the following is an inflorescence?

A. Tendril
Explanation: Incorrect. For climbing.

B. Raceme
Answer: Correct. Raceme is a type of inflorescence.

C. Stamen
Explanation: Incorrect. Part of androecium.

D. Root cap
Explanation: Incorrect. Protects root tip.

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Q45. Example of dicot seed with endosperm is:

A. Bean
Explanation: Incorrect. Bean lacks endosperm.

B. Castor
Answer: Correct. Castor seed is endospermic dicot.

C. Gram
Explanation: Incorrect. Gram is non-endospermic.

D. Pea
Explanation: Incorrect. Pea is non-endospermic.

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Q46. Aleurone layer in seeds is rich in:

A. Lipids
Explanation: Incorrect. Lipids stored in endosperm.

B. Proteins
Answer: Correct. Aleurone layer stores protein granules.

C. Starch
Explanation: Incorrect. Stored in cotyledons/endosperm.

D. Minerals
Explanation: Incorrect. Not main storage.

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Q47. Which of the following is not a fruit?

A. Mango
Explanation: Incorrect. Mango is a drupe fruit.

B. Potato
Answer: Correct. Potato is a stem tuber, not fruit.

C. Apple
Explanation: Incorrect. Apple is a false fruit.

D. Banana
Explanation: Incorrect. Banana is a parthenocarpic fruit.

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Q48. Polyembryony is common in:

A. Rice
Explanation: Incorrect. Rare in cereals.

B. Citrus
Answer: Correct. Nucellar embryony produces multiple embryos.

C. Pea
Explanation: Incorrect. Not common.

D. Sunflower
Explanation: Incorrect. Rare occurrence.

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Q49. Long-day plants flower when:

A. Night length is longer than critical period
Explanation: Incorrect. That induces short-day plants.

B. Day length exceeds critical period
Answer: Correct. Long-day plants need longer photoperiod.

C. Night length is short
Explanation: Related, but less precise.

D. Photoperiod has no role
Explanation: Incorrect. Photoperiodism is key.

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Q50. Hydrophytes are characterized by:

A. Thick cuticle
Explanation: Incorrect. Found in xerophytes.

B. Aerenchyma and reduced mechanical tissues
Answer: Correct. Adaptation for buoyancy and support.

C. Sunken stomata
Explanation: Incorrect. Found in xerophytes.

D. Extensive secondary growth
Explanation: Incorrect. Not typical in hydrophytes.

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Botany MCQs (Part 3: Q51–75)

Important for CBSE/State Boards, NEET, CUET, CSIR-NET, GATE, Medical Entrances & Olympiads

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Q51. Perisperm in seeds is derived from:

A. Zygote
Explanation: Incorrect. Zygote develops into embryo.

B. Nucellus
Answer: Correct. Perisperm is residual nucellus tissue.

C. Endosperm
Explanation: Incorrect. Endosperm comes from double fertilization.

D. Integuments
Explanation: Incorrect. Integuments form seed coat.

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Q52. Function of coleoptile in monocot seeds is:

A. Protects radicle
Explanation: Incorrect. Radicle is protected by coleorhiza.

B. Protects plumule during germination
Answer: Correct. Coleoptile covers and safeguards the plumule.

C. Food storage
Explanation: Incorrect. Food is in endosperm/cotyledon.

D. Photosynthesis
Explanation: Incorrect. Not photosynthetic.

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Q53. Which of the following is a dry indehiscent fruit?

A. Mustard capsule
Explanation: Incorrect. Dehiscent fruit.

B. Maize grain
Answer: Correct. Caryopsis is dry and indehiscent.

C. Pea pod
Explanation: Incorrect. Splits open.

D. Cotton capsule
Explanation: Incorrect. Capsule is dehiscent.

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Q54. Which pigment is water soluble?

A. Chlorophyll
Explanation: Incorrect. Insoluble in water.

B. Carotene
Explanation: Incorrect. Fat soluble.

C. Anthocyanin
Answer: Correct. Anthocyanins are water-soluble pigments.

D. Xanthophyll
Explanation: Incorrect. Fat soluble.

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Q55. Red drop effect in photosynthesis was explained by:

A. Blackman
Explanation: Incorrect. Proposed law of limiting factors.

B. Emerson
Answer: Correct. Discovered two photosystems by red drop experiment.

C. Calvin
Explanation: Incorrect. Known for Calvin cycle.

D. Hill
Explanation: Incorrect. Hill reaction involves photolysis.

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Q56. Kranz anatomy is seen in:

A. Monocot roots
Explanation: Incorrect. Roots lack Kranz anatomy.

B. C4 leaves
Answer: Correct. Bundle sheath cells with chloroplasts form Kranz anatomy.

C. Gymnosperm leaves
Explanation: Incorrect. Absent in gymnosperms.

D. Dicot stems
Explanation: Incorrect. Not seen here.

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Q57. The Hill reaction demonstrates:

A. CO₂ fixation
Explanation: Incorrect. Hill reaction does not involve CO₂.

B. Photolysis of water releasing O₂
Answer: Correct. Hill showed O₂ comes from water.

C. ATP breakdown
Explanation: Incorrect. It involves ATP synthesis.

D. Calvin cycle
Explanation: Incorrect. Hill is a light reaction, not Calvin cycle.

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Q58. CAM pathway plants are adapted to:

A. Aquatic conditions
Explanation: Incorrect. CAM plants are not hydrophytes.

B. Arid, dry conditions
Answer: Correct. CAM reduces water loss in deserts.

C. Cold regions
Explanation: Incorrect. Cold adaptation differs.

D. Temperate grasslands
Explanation: Incorrect. CAM rare here.

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Q59. The “respiratory quotient (RQ)” is the ratio of:

A. O₂ released / CO₂ absorbed
Explanation: Incorrect. Reverse of actual definition.

B. CO₂ released / O₂ consumed
Answer: Correct. RQ indicates substrate being respired.

C. ATP produced / ADP consumed
Explanation: Incorrect. Not definition of RQ.

D. CO₂ absorbed / ATP produced
Explanation: Incorrect. Not relevant.

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Q60. The end product of glycolysis is:

A. Acetyl CoA
Explanation: Incorrect. Produced after pyruvate oxidation.

B. Pyruvic acid
Answer: Correct. Glycolysis produces two pyruvate molecules.

C. Lactic acid
Explanation: Incorrect. Forms only in anaerobic respiration.

D. Ethanol
Explanation: Incorrect. Produced in yeast fermentation.

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Q61. The site of Krebs cycle in plant cells is:

A. Cytoplasm
Explanation: Incorrect. Glycolysis occurs in cytoplasm.

B. Mitochondrial matrix
Answer: Correct. Krebs cycle occurs in mitochondrial matrix.

C. Chloroplast
Explanation: Incorrect. Calvin cycle occurs in chloroplast.

D. Peroxisome
Explanation: Incorrect. Photorespiration occurs partly here.

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Q62. Glyoxysomes are specialized peroxisomes found in:

A. Leaves
Explanation: Incorrect. Found in germinating oil seeds, not leaves.

B. Germinating fatty seeds
Answer: Correct. Convert fats into sugars during germination.

C. Roots
Explanation: Incorrect. Not in roots.

D. Stem apices
Explanation: Incorrect. Not found here.

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Q63. The pentose phosphate pathway occurs in:

A. Nucleus
Explanation: Incorrect. Metabolic pathway, not nuclear.

B. Cytoplasm
Answer: Correct. HMP shunt takes place in cytoplasm.

C. Mitochondria
Explanation: Incorrect. Krebs cycle occurs there.

D. Chloroplast
Explanation: Incorrect. Calvin cycle occurs there.

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Q64. Cytochromes are mainly involved in:

A. Nitrogen fixation
Explanation: Incorrect. Enzyme nitrogenase fixes nitrogen.

B. Electron transport chain
Answer: Correct. Cytochromes are electron carriers.

C. Protein synthesis
Explanation: Incorrect. Done by ribosomes.

D. DNA replication
Explanation: Incorrect. DNA polymerase replicates DNA.

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Q65. The main site of photorespiration in plants is:

A. Chloroplast only
Explanation: Incorrect. Not confined to chloroplast.

B. Chloroplast, peroxisome, mitochondria
Answer: Correct. Photorespiration occurs across three organelles.

C. Cytoplasm only
Explanation: Incorrect. Not cytoplasmic.

D. Nucleus only
Explanation: Incorrect. Nucleus is not involved.

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Q66. The glyoxylate cycle bypasses:

A. Glycolysis
Explanation: Incorrect. Glycolysis is separate.

B. Decarboxylation steps of Krebs cycle
Answer: Correct. Allows conversion of fats to carbohydrates.

C. Calvin cycle
Explanation: Incorrect. Not relevant.

D. Electron transport chain
Explanation: Incorrect. Not bypassed.

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Q67. Aerenchyma in hydrophytes provides:

A. Support in dry areas
Explanation: Incorrect. Xerophytes adapt differently.

B. Buoyancy and aeration
Answer: Correct. Aerenchyma aids floating and gas exchange.

C. Water absorption
Explanation: Incorrect. Roots absorb water.

D. Food storage
Explanation: Incorrect. Not primary function.

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Q68. Haemoglobin-like pigment in legume root nodules is:

A. Myoglobin
Explanation: Incorrect. Found in animals.

B. Leghemoglobin
Answer: Correct. Ensures low O₂ concentration for nitrogenase.

C. Phycocyanin
Explanation: Incorrect. Found in cyanobacteria.

D. Chlorophyll
Explanation: Incorrect. Pigment for photosynthesis.

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Q69. Nitrogenase enzyme is inactivated by:

A. Carbon dioxide
Explanation: Incorrect. Not inhibitor.

B. Oxygen
Answer: Correct. Nitrogenase is oxygen-sensitive.

C. Nitrate ions
Explanation: Incorrect. Does not directly inhibit.

D. Hydrogen ions
Explanation: Incorrect. Not relevant.

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Q70. The first stable compound in nitrogen assimilation is:

A. Urea
Explanation: Incorrect. Not an assimilated compound.

B. Glutamine / Glutamate
Answer: Correct. Amino acids formed during assimilation.

C. Ammonia
Explanation: Incorrect. Precursor but toxic.

D. Nitrate
Explanation: Incorrect. Reduced before assimilation.

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Q71. Symbiotic nitrogen fixation in legumes requires:

A. Phycobilins
Explanation: Incorrect. Cyanobacteria pigment.

B. Rhizobium bacteria
Answer: Correct. Rhizobium lives in root nodules.

C. Viruses
Explanation: Incorrect. Not involved.

D. Mycorrhiza only
Explanation: Incorrect. Mycorrhiza is fungi, not N₂ fixer.

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Q72. The Haber process is related to:

A. Photosynthesis
Explanation: Incorrect. Artificial ammonia synthesis, not photosynthesis.

B. Industrial nitrogen fixation
Answer: Correct. N₂ + H₂ → NH₃ under high temperature & pressure.

C. Respiration
Explanation: Incorrect. Not related.

D. Fermentation
Explanation: Incorrect. Not Haber process.

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Q73. Nitrifying bacteria convert:

A. Ammonia → Nitrite → Nitrate
Answer: Correct. Nitrosomonas and Nitrobacter perform nitrification.

B. Nitrate → Ammonia
Explanation: Incorrect. That’s ammonification.

C. Nitrogen gas → Ammonia
Explanation: Incorrect. That’s nitrogen fixation.

D. Nitrate → Nitrogen gas
Explanation: Incorrect. That’s denitrification.

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Q74. Denitrification is carried out by:

A. Nitrosomonas
Explanation: Incorrect. Oxidizes ammonia.

B. Pseudomonas
Answer: Correct. Converts nitrate to nitrogen gas.

C. Rhizobium
Explanation: Incorrect. Nitrogen fixer.

D. Azotobacter
Explanation: Incorrect. Fixes nitrogen, not denitrification.

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Q75. Essential micronutrient for chlorophyll synthesis is:

A. Calcium
Explanation: Incorrect. Structural role, not chlorophyll synthesis.

B. Magnesium
Answer: Correct. Central atom in chlorophyll.

C. Sulphur
Explanation: Incorrect. Present in proteins.

D. Sodium
Explanation: Incorrect. Not essential for chlorophyll.

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Botany MCQs (Part 4: Q76–100)

Important for CBSE/State Boards, NEET, CUET, CSIR-NET, GATE, Medical Entrances & Olympiads

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Q76. Which element is a constituent of proteins but not carbohydrates?

A. Carbon
Explanation: Incorrect. Found in both proteins and carbohydrates.

B. Nitrogen
Answer: Correct. Proteins contain nitrogen, carbohydrates do not.

C. Hydrogen
Explanation: Incorrect. Found in both.

D. Oxygen
Explanation: Incorrect. Found in both.

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Q77. Deficiency of which element causes chlorosis?

A. Calcium
Explanation: Incorrect. Calcium deficiency causes stunted growth.

B. Magnesium
Answer: Correct. Magnesium deficiency reduces chlorophyll → chlorosis.

C. Phosphorus
Explanation: Incorrect. Deficiency causes poor root growth.

D. Potassium
Explanation: Incorrect. Causes necrosis at leaf margins.

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Q78. The process of movement of ions against concentration gradient is called:

A. Diffusion
Explanation: Incorrect. Diffusion is passive.

B. Active transport
Answer: Correct. Requires energy (ATP).

C. Osmosis
Explanation: Incorrect. Osmosis is passive water movement.

D. Facilitated diffusion
Explanation: Incorrect. Passive transport with carrier proteins.

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Q79. Imbibition is:

A. Movement of water across semi-permeable membrane
Explanation: Incorrect. That is osmosis.

B. Absorption of water by colloids like seeds
Answer: Correct. Imbibition causes swelling of seeds.

C. Movement of ions through xylem
Explanation: Incorrect. That is conduction.

D. Loss of water as vapor
Explanation: Incorrect. That is transpiration.

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Q80. Cohesion-tension theory explains:

A. Translocation of food
Explanation: Incorrect. Food translocation is explained by mass flow.

B. Ascent of sap in xylem
Answer: Correct. Water moves upward due to transpiration pull + cohesion.

C. ATP synthesis in chloroplast
Explanation: Incorrect. Chemiosmosis explains that.

D. Gas exchange in stomata
Explanation: Incorrect. Not related.

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Q81. The Münch hypothesis explains:

A. Water transport
Explanation: Incorrect. Cohesion theory explains water transport.

B. Translocation of food in phloem
Answer: Correct. Mass flow hypothesis describes phloem transport.

C. Root pressure
Explanation: Incorrect. Root pressure is separate.

D. Guttation
Explanation: Incorrect. Not explained by Münch hypothesis.

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Q82. Which enzyme is called the “carboxylase/oxygenase”?

A. Hexokinase
Explanation: Incorrect. Catalyzes glucose phosphorylation.

B. RuBisCO
Answer: Correct. Catalyzes both CO₂ fixation and O₂ binding.

C. PEP carboxylase
Explanation: Incorrect. Only carboxylase, not oxygenase.

D. Catalase
Explanation: Incorrect. Breaks down hydrogen peroxide.

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Q83. The respiratory quotient (RQ) of fats is usually:

A. 1
Explanation: Incorrect. RQ = 1 for carbohydrates.

B. < 1 (around 0.7)
Answer: Correct. Fats require more O₂, hence RQ < 1.

C. > 1
Explanation: Incorrect. RQ > 1 for organic acids.

D. Zero
Explanation: Incorrect. Not possible during respiration.

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Q84. Anaerobic respiration in yeast produces:

A. Lactic acid
Explanation: Incorrect. Produced in muscles.

B. Ethanol and CO₂
Answer: Correct. Yeast fermentation produces ethanol and CO₂.

C. Acetyl-CoA
Explanation: Incorrect. Produced aerobically.

D. Glucose
Explanation: Incorrect. Glucose is the substrate.

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Q85. Which plant is popularly called “Amphibian of the Plant Kingdom”?

A. Gymnosperms
Explanation: Incorrect. They are seed plants.

B. Bryophytes
Answer: Correct. Need water for reproduction, but live on land.

C. Pteridophytes
Explanation: Incorrect. More advanced than bryophytes.

D. Angiosperms
Explanation: Incorrect. True flowering plants.

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Q86. Protonema is found in:

A. Ferns
Explanation: Incorrect. They produce prothallus.

B. Mosses (Bryophytes)
Answer: Correct. Protonema is the juvenile stage of moss gametophyte.

C. Gymnosperms
Explanation: Incorrect. No protonema stage.

D. Angiosperms
Explanation: Incorrect. Not found.

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Q87. In pteridophytes, the dominant phase is:

A. Gametophyte
Explanation: Incorrect. Gametophyte is reduced.

B. Sporophyte
Answer: Correct. Sporophyte is independent and dominant.

C. Equal phases
Explanation: Incorrect. Sporophyte dominates.

D. No alternation
Explanation: Incorrect. Alternation exists.

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Q88. Azolla is used in paddy fields because:

A. Provides shade
Explanation: Incorrect. Main role is nitrogen fixation.

B. Fixes atmospheric nitrogen through Anabaena
Answer: Correct. Symbiotic cyanobacteria in Azolla fix nitrogen.

C. Produces oxygen only
Explanation: Incorrect. Not the main use.

D. Acts as insect repellent
Explanation: Incorrect. Not its function.

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Q89. Which algae is known as “brown algae”?

A. Chlamydomonas
Explanation: Incorrect. Green algae.

B. Laminaria
Answer: Correct. Laminaria is brown algae (Phaeophyceae).

C. Spirogyra
Explanation: Incorrect. Green algae.

D. Red algae
Explanation: Incorrect. Separate group (Rhodophyceae).

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Q90. Floridean starch is stored in:

A. Brown algae
Explanation: Incorrect. They store laminarin and mannitol.

B. Red algae
Answer: Correct. Floridean starch is unique to Rhodophyceae.

C. Green algae
Explanation: Incorrect. They store starch.

D. Cyanobacteria
Explanation: Incorrect. Store cyanophycean starch.

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Q91. Sargassum is a:

A. Green alga
Explanation: Incorrect. Belongs to brown algae.

B. Brown alga
Answer: Correct. Sargassum is a brown alga, floating in Sargasso Sea.

C. Red alga
Explanation: Incorrect. Not in Rhodophyceae.

D. Cyanobacterium
Explanation: Incorrect. Not bacteria.

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Q92. Agar is obtained from:

A. Spirogyra
Explanation: Incorrect. Does not produce agar.

B. Red algae (Gelidium/Gracilaria)
Answer: Correct. Agar is a product of red algae.

C. Brown algae
Explanation: Incorrect. Produces alginates, not agar.

D. Cyanobacteria
Explanation: Incorrect. Not a source.

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Q93. Which algae is called “kelp”?

A. Spirogyra
Explanation: Incorrect. Filamentous green alga.

B. Macrocystis
Answer: Correct. Macrocystis pyrifera is giant kelp.

C. Polysiphonia
Explanation: Incorrect. Red alga.

D. Volvox
Explanation: Incorrect. Colonial green alga.

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Q94. The cell wall of fungi is made of:

A. Cellulose
Explanation: Incorrect. Found in plants.

B. Chitin
Answer: Correct. Fungal walls contain chitin and glucans.

C. Pectin
Explanation: Incorrect. Found in middle lamella.

D. Lignin
Explanation: Incorrect. Found in xylem.

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Q95. Lichens are a symbiotic association of:

A. Algae and fungi
Answer: Correct. Alga (food) + fungus (shelter).

B. Bacteria and fungus
Explanation: Incorrect. Not standard lichen.

C. Moss and algae
Explanation: Incorrect. Not lichen.

D. Fungi and protozoa
Explanation: Incorrect. Not lichen.

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Q96. In gymnosperms, the seeds are:

A. Enclosed in fruit
Explanation: Incorrect. Angiosperm feature.

B. Naked, not enclosed by fruit
Answer: Correct. Gymnosperms have naked seeds.

C. Without ovules
Explanation: Incorrect. Seeds come from ovules.

D. Non-vascular
Explanation: Incorrect. Gymnosperms are vascular.

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Q97. Cycas belongs to which group?

A. Angiosperms
Explanation: Incorrect. Cycas is not a flowering plant.

B. Gymnosperms
Answer: Correct. Cycas is a living gymnosperm.

C. Bryophytes
Explanation: Incorrect. Non-vascular plants.

D. Pteridophytes
Explanation: Incorrect. Lower vascular plants.

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Q98. The largest ovule among gymnosperms is found in:

A. Pinus
Explanation: Incorrect. Ovules smaller.

B. Cycas
Answer: Correct. Cycas ovules are largest in plant kingdom.

C. Ginkgo
Explanation: Incorrect. Smaller ovules.

D. Ephedra
Explanation: Incorrect. Ovules are not the largest.

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Q99. The pollination in gymnosperms is mostly:

A. Insect-pollinated
Explanation: Incorrect. Pollination rarely by insects.

B. Wind-pollinated
Answer: Correct. Gymnosperms rely on wind.

C. Water-pollinated
Explanation: Incorrect. Not aquatic pollination.

D. Animal-pollinated
Explanation: Incorrect. No animals involved.

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Q100. Which plant group is considered the most advanced in evolution?

A. Bryophytes
Explanation: Incorrect. Primitive land plants.

B. Pteridophytes
Explanation: Incorrect. Lower vascular plants.

C. Gymnosperms
Explanation: Incorrect. Naked seed plants.

D. Angiosperms
Answer: Correct. Flowering plants with double fertilization.

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