2026 MCQ questions most difficult and important questions which maycome important questions biology
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Here are 50 high-difficulty, high-importance Biology MCQs for KCET 2026 — covering all major topics based on the Karnataka PUC syllabus and previous year KCET patterns.
🧬 KCET 2026 Biology — Top 50 Important MCQs
📌 UNIT 1: Diversity in Living World
Q1. Which of the following is NOT a characteristic of Kingdom Monera?
- A) Absence of membrane-bound organelles
- B) 70S ribosomes
- C) Presence of peptidoglycan in cell wall
- D) Presence of nuclear membrane
✅ Answer: D — Monera (prokaryotes) lack nuclear membrane.
Q2. Mycorrhiza is an example of:
- A) Parasitism
- B) Mutualism
- C) Commensalism
- D) Amensalism
✅ Answer: B — Fungi and plant roots form a mutualistic association.
Q3. Chromatophores in algae are:
- A) Membrane-bound pigment organelles
- B) Naked pigment-bearing structures
- C) Plastids with multiple pigments
- D) Pigmented cell walls
✅ Answer: B — In algae, chromatophores are naked (not membrane-bound).
Q4. Which division of plants is called "Amphibians of plant kingdom"?
- A) Pteridophyta
- B) Bryophyta
- C) Gymnosperms
- D) Algae
✅ Answer: B — Bryophytes need water for reproduction but live on land.
Q5. Heterospory is seen in which of the following?
- A) Selaginella and Salvinia
- B) Funaria and Marchantia
- C) Cycas and Pinus
- D) Spirogyra and Ulothrix
✅ Answer: A — Selaginella and Salvinia are heterosporous pteridophytes.
📌 UNIT 2: Structural Organisation in Animals & Plants
Q6. The vascular bundle in monocot stem is:
- A) Open, collateral
- B) Closed, collateral
- C) Bicollateral, open
- D) Radial, closed
✅ Answer: B — Monocot stem has closed collateral vascular bundles (no cambium).
Q7. Which type of epithelium lines the inner surface of blood vessels?
- A) Cuboidal epithelium
- B) Columnar epithelium
- C) Squamous epithelium
- D) Ciliated epithelium
✅ Answer: C — Simple squamous (endothelium) lines blood vessels.
Q8. Sclereids (stone cells) are a type of:
- A) Parenchyma
- B) Collenchyma
- C) Sclerenchyma
- D) Meristematic tissue
✅ Answer: C — Sclereids are dead sclerenchyma cells with thick, lignified walls.
Q9. In earthworm, the typhlosole is associated with:
- A) Excretion
- B) Reproduction
- C) Increasing absorptive surface in intestine
- D) Circulation
✅ Answer: C
Q10. Haversian canals are found in:
- A) Cartilage
- B) Compact bone
- C) Spongy bone
- D) Tendon
✅ Answer: B
📌 UNIT 3: Cell Structure & Function
Q11. Which of the following is the CORRECT sequence of cell cycle phases?
- A) G1 → S → G2 → M
- B) S → G1 → G2 → M
- C) G1 → G2 → S → M
- D) M → G1 → S → G2
✅ Answer: A
Q12. During which phase of meiosis does crossing over occur?
- A) Leptotene
- B) Zygotene
- C) Pachytene
- D) Diplotene
✅ Answer: C — Crossing over occurs during pachytene of Meiosis I.
Q13. Fluid mosaic model of plasma membrane was proposed by:
- A) Watson and Crick
- B) Robertson
- C) Singer and Nicolson
- D) Danielli and Davson
✅ Answer: C
Q14. Which organelle is called the "powerhouse of the cell"?
- A) Ribosome
- B) Nucleus
- C) Mitochondria
- D) Golgi body
✅ Answer: C
Q15. F₁ particle (elementary particle) on mitochondria is involved in:
- A) Electron transport
- B) ATP synthesis
- C) Fatty acid oxidation
- D) Protein synthesis
✅ Answer: B
📌 UNIT 4: Plant Physiology
Q16. Which pigment absorbs light maximally at 660 nm (red light)?
- A) Phytochrome Pfr
- B) Phytochrome Pr
- C) Cryptochrome
- D) Carotenoid
✅ Answer: B — Pr absorbs red light (660 nm) and converts to Pfr.
Q17. C4 plants are more efficient than C3 plants because:
- A) They lack photorespiration
- B) They fix CO₂ in bundle sheath cells
- C) They use PEP carboxylase in mesophyll cells
- D) All of the above
✅ Answer: D
Q18. Guttation occurs through:
- A) Stomata
- B) Lenticels
- C) Hydathodes
- D) Cuticle
✅ Answer: C
Q19. Which hormone promotes apical dominance?
- A) Gibberellin
- B) Cytokinin
- C) Auxin (IAA)
- D) Abscisic acid
✅ Answer: C
Q20. Vernalization is related to:
- A) Effect of light on flowering
- B) Effect of low temperature on flowering
- C) Effect of temperature on seed germination
- D) Effect of day length on vegetative growth
✅ Answer: B
📌 UNIT 5: Human Physiology
Q21. The enzyme responsible for converting fibrinogen to fibrin in blood clotting is:
- A) Thromboplastin
- B) Thrombin
- C) Fibrinase
- D) Prothrombin
✅ Answer: B
Q22. Tidal volume in a normal adult at rest is approximately:
- A) 1200 mL
- B) 500 mL
- C) 2300 mL
- D) 3500 mL
✅ Answer: B
Q23. Which part of the nephron is impermeable to water but permeable to NaCl?
- A) Proximal convoluted tubule
- B) Descending limb of loop of Henle
- C) Ascending limb of loop of Henle
- D) Collecting duct
✅ Answer: C
Q24. Pacemaker of the heart is:
- A) AV node
- B) Bundle of His
- C) SA node
- D) Purkinje fibers
✅ Answer: C
Q25. Which of the following hormones is a steroid?
- A) Insulin
- B) Adrenaline
- C) Testosterone
- D) Oxytocin
✅ Answer: C
Q26. The enzyme trypsinogen is activated by:
- A) Pepsin
- B) Enterokinase
- C) Lipase
- D) Amylase
✅ Answer: B
Q27. Carbaminohaemoglobin is formed when haemoglobin binds with:
- A) O₂
- B) CO
- C) CO₂
- D) N₂
✅ Answer: C
Q28. ADH (Vasopressin) acts on which part of the kidney?
- A) Glomerulus
- B) Proximal convoluted tubule
- C) Loop of Henle
- D) Distal convoluted tubule and collecting duct
✅ Answer: D
📌 UNIT 6: Reproduction
Q29. Double fertilization in angiosperms results in:
- A) Endosperm (3n) + Embryo (2n)
- B) Endosperm (2n) + Embryo (3n)
- C) Two embryos
- D) Endosperm (2n) + Embryo (2n)
✅ Answer: A
Q30. Capacitation refers to:
- A) Maturation of ovum
- B) Activation/maturation of spermatozoa in female genital tract
- C) Implantation of embryo
- D) Formation of acrosome
✅ Answer: B
Q31. The hormone responsible for parturition (childbirth) is:
- A) Estrogen
- B) Progesterone
- C) Relaxin and Oxytocin
- D) Prolactin
✅ Answer: C
Q32. Which contraceptive method has the highest failure rate?
- A) IUD
- B) Condom
- C) Rhythm method (natural)
- D) Oral contraceptive pills
✅ Answer: C
📌 UNIT 7: Genetics & Evolution
Q33. A test cross is used to determine:
- A) Sex of offspring
- B) Genotype of an organism showing dominant phenotype
- C) Linkage between genes
- D) Mutation rate
✅ Answer: B
Q34. Which of the following is an example of co-dominance?
- A) ABO blood group
- B) Skin color
- C) Height in humans
- D) Pea flower color
✅ Answer: A
Q35. A dihybrid cross (AaBb × AaBb) gives offspring in the ratio:
- A) 9:3:3:1
- B) 1:2:1
- C) 3:1
- D) 1:1:1:1
✅ Answer: A
Q36. The "one gene-one enzyme" hypothesis was given by:
- A) Watson and Crick
- B) Beadle and Tatum
- C) Griffith
- D) Hershey and Chase
✅ Answer: B
Q37. Which of the following mutations causes sickle cell anaemia?
- A) Deletion of a codon
- B) Substitution of glutamic acid by valine at 6th position of β-globin
- C) Addition of an amino acid
- D) Frameshift mutation
✅ Answer: B
Q38. The concept of "Pangenesis" was given by:
- A) Darwin
- B) Lamarck
- C) De Vries
- D) Mendel
✅ Answer: A — Darwin proposed pangenesis to explain heredity (later disproved).
Q39. Hardy-Weinberg equilibrium is disturbed by:
- A) Random mating
- B) Large population size
- C) Genetic drift and natural selection
- D) No migration
✅ Answer: C
📌 UNIT 8: Biotechnology
Q40. Restriction endonucleases cut DNA at specific sequences called:
- A) Promoter sites
- B) Palindromic sequences
- C) TATA boxes
- D) Operator sites
✅ Answer: B
Q41. The vector used in Agrobacterium tumefaciens mediated gene transfer is:
- A) pBR322
- B) λ phage
- C) Ti plasmid
- D) BAC vector
✅ Answer: C
Q42. PCR (Polymerase Chain Reaction) is used to:
- A) Translate mRNA into protein
- B) Amplify a specific DNA segment
- C) Transcribe DNA into RNA
- D) Clone an organism
✅ Answer: B
Q43. Bt cotton is resistant to bollworm because it produces:
- A) Chitinase enzyme
- B) Cry proteins (δ-endotoxins)
- C) Trypsin inhibitor
- D) Lectin
✅ Answer: B
Q44. ELISA is based on the principle of:
- A) Antigen-antibody interaction
- B) Nucleic acid hybridization
- C) Gel electrophoresis
- D) PCR amplification
✅ Answer: A
📌 UNIT 9: Ecology
Q45. Which of the following is a keystone species?
- A) A species with the largest biomass
- B) A species that has a disproportionately large effect on its ecosystem relative to its abundance
- C) A species that is most abundant
- D) A producer species
✅ Answer: B
Q46. The pyramid of energy is always:
- A) Inverted
- B) Upright
- C) Spindle-shaped
- D) Can be both upright and inverted
✅ Answer: B — Energy pyramid is ALWAYS upright.
Q47. Which gas is primarily responsible for global warming?
- A) SO₂
- B) CO₂
- C) O₃
- D) NO₂
✅ Answer: B
Q48. The 10% energy transfer law was given by:
- A) Lindeman
- B) Tansley
- C) Elton
- D) Odum
✅ Answer: A — Lindeman's 10% law (1942).
Q49. In which type of biome is the greatest biodiversity found?
- A) Temperate deciduous forest
- B) Tropical rainforest
- C) Savanna grassland
- D) Boreal forest (Taiga)
✅ Answer: B
Q50. Ex-situ conservation includes:
- A) Wildlife sanctuaries
- B) Biosphere reserves
- C) Seed banks and zoological parks
- D) National parks
✅ Answer: C
📊 KCET 2026 — Topic-Wise Weightage Guide
| Topic | Expected Questions | Difficulty |
|---|---|---|
| Human Physiology | 8–10 | High |
| Genetics & Evolution | 7–9 | High |
| Reproduction | 5–7 | Medium |
| Biotechnology | 5–6 | High |
| Ecology | 5–6 | Medium |
| Plant Physiology | 4–5 | Medium |
| Cell Biology | 4–5 | Medium |
| Diversity (Taxonomy) | 3–4 | Low–Medium |
🎯 Key Tips for KCET 2026 Biology
- Human Physiology (digestion, respiration, excretion, circulation, nervous system) — always the highest scoring unit.
- Genetics — Mendelian ratios, codominance, linkage, mutations are repeated every year.
- Biotechnology — restriction enzymes, PCR, GMOs are very frequently asked.
- Ecology — pyramids, biodiversity, conservation terms appear reliably.
- NCERT is primary — KCET questions are almost entirely NCERT-based; stick to Class 11 & 12 NCERT Biology.
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