🔬 Answer Key · Biology
PART 1 · Questions 1–5 (any 3, 1 score each)
1
Which kingdom includes multicellular, heterotrophic organism with chitin in their cell walls?
Answer: Fungi
2
Which plant group has vascular tissues but no seeds? (a) Bryophytes (b) Algae (c) Pteridophytes (d) Gymnosperm
Answer: (c) Pteridophytes
3
The type of venation found in dicot leaves is ______.
Answer: Reticulate venation
4
Meiosis I : Reductional division :: Meiosis II : ______
Answer: Equational division
5
Name the meristem responsible for primary growth of plants.
Answer: Apical meristem
PART 2 · Questions 6–16 (answer any 9, 2 scores)
6
What causes red tides and what are their effects?
Answer: Caused by rapid multiplication of dinoflagellates (e.g., Gonyaulax). Effects: produce toxins killing marine life; can cause illness/death in humans consuming contaminated seafood.
10
Observe the diagram (chloroplast). (a) Identify the Plastid (b) Label parts A & B (c) Ribosome type?
Answer: (a) Chloroplast
(b) A = Granum / grana (stack of thylakoids); B = Stroma
(c) 70S ribosomes
⚡ based on standard chloroplast diagram
(b) A = Granum / grana (stack of thylakoids); B = Stroma
(c) 70S ribosomes
11(b)
Which cell organelle possesses hydrolytic enzymes?
Answer: Lysosome
13
(a) What is Respiratory Quotient? (b) Name any two substrates used for respiration.
Answer: (a) RQ = volume of CO₂ released / volume of O₂ consumed. (b) Carbohydrates (glucose), Fats (fatty acids), Proteins (any two).
14
(a) Two compounds from Krebs cycle that yield ATP via oxidative phosphorylation. (b) ATP from each?
Answer: (a) NADH and FADH₂. (b) ~3 ATP from NADH; ~2 ATP from FADH₂.
15
Match plant hormone with function: Auxin, Gibberellin, Cytokinin, Ethylene. (functions: ripening, overcome apical dominance, increase sugarcane stem, parthenocarpy)
Answer:
Auxin → induction of parthenocarpy
Gibberellin → increases length of stem in sugarcane
Cytokinin → helps to overcome apical dominance
Ethylene → ripening of fruits
Auxin → induction of parthenocarpy
Gibberellin → increases length of stem in sugarcane
Cytokinin → helps to overcome apical dominance
Ethylene → ripening of fruits
16
"Plant growth generally is Indeterminate." Evaluate.
Answer: True. Meristems retain ability to divide throughout life, allowing continuous growth (unlike determinate growth in animals).
18
Cell cycle diagram: (a) stages A, B, C? (b) haploid mitosis example? (c) why S phase called synthesis?
Answer: (a) A = Interphase (G1+S+G2), B = M phase / Mitosis, C = Cytokinesis. (b) Male honeybee (drone). (c) Because DNA synthesis (replication) occurs.
20
TCA cycle: (a) label A, B, C, D (b) scientist? (c) step where GTP synthesised?
Answer: (a) Typical: A = Acetyl CoA, B = Citrate, C = α-ketoglutarate, D = Succinate. (b) Sir Hans Adolf Krebs. (c) Conversion of Succinyl CoA → Succinate (Succinyl CoA synthetase).
PART 3 · Page 6–9 (I, II, III)
I · (1 score each)
1
Arrange taxonomic categories in ascending order: Genus, Family, Order, Class, Species, Phylum, Kingdom
Answer: Species → Genus → Family → Order → Class → Phylum → Kingdom
2
Inhibitor closely resembling substrate and inhibiting enzyme activity is known as
Answer: Competitive inhibitor
3
Volume of air remaining in lungs even after forcible expiration
Answer: Residual volume (RV)
4
Joint between adjacent vertebrae that permits limited movements
Answer: Cartilaginous joint / intervertebral disc joint
5
Disorder with glucose loss in urine, treated with insulin therapy.
Answer: Diabetes mellitus
II · (2 scores each)
8
Differentiate aestivation and hibernation.
Answer: Aestivation = summer sleep / dormancy to escape heat & dry conditions. Hibernation = winter sleep to escape cold & conserve energy.
9
Enzyme action: E + S ⇌ ES → EP → E + P. (a) Expand ES, EP. (b) Two factors affecting enzyme action.
Answer: (a) ES = Enzyme-Substrate complex; EP = Enzyme-Product complex. (b) Temperature, pH, concentration, inhibitors (any two).
10
(a) Name organisms A and B (starfish & earthworm typical). (b) Their phyla.
Answer (representative): A = Starfish (Asterias) — Phylum Echinodermata; B = Earthworm (Pheretima) — Phylum Annelida.
11
Write suitable terms: (a) hollow bones with air cavities (b) living organism emits light (c) sexes not separate (d) warm-blooded.
Answer: (a) Pneumatic bones (b) Bioluminescence (c) Bisexual / hermaphrodite (d) Homeotherms / endotherms.
15
Match: Renal calculi, Uremia, Renal failure, Glomerulonephritis
Answer:
Renal calculi → Stone / insoluble salt mass
Uremia → Accumulation of urea in blood
Renal failure → Kidney transplantation
Glomerulonephritis → Inflammation of glomeruli
Renal calculi → Stone / insoluble salt mass
Uremia → Accumulation of urea in blood
Renal failure → Kidney transplantation
Glomerulonephritis → Inflammation of glomeruli
16
Identify endocrine glands A and B (brain region typical).
Answer (common): A = Pituitary gland; B = Pineal gland (or thyroid lobes depending on diagram).
III · (3 scores each)
17
Brain part controlling: (a) body temperature, urge eating/drinking (b) sensory association, memory (c) respiration, cardiovascular reflexes.
Answer: (a) Hypothalamus (b) Cerebrum / cerebral cortex (c) Medulla oblongata.
18
(a) Process to remove urea from blood. (b) two processes in urine formation. (c) mechanism maintaining medullary gradient.
Answer: (a) Hemodialysis / dialysis. (b) Ultrafiltration, tubular reabsorption, tubular secretion (any two). (c) Countercurrent mechanism.
19
(a) Inspiration/Expiration table: find A and B. (b) two methods of CO₂ transport.
Answer: (a) A = Diaphragm & intercostal muscles relax; B = Intra-pulmonary pressure decreases.
(b) 1. As bicarbonate ions (HCO₃⁻); 2. As carbamino-haemoglobin; 3. Dissolved in plasma (any two).
(b) 1. As bicarbonate ions (HCO₃⁻); 2. As carbamino-haemoglobin; 3. Dissolved in plasma (any two).
20
(Earlier TCA cycle question, repeated in some parts)
Refer to Q20 answer above.
⚠️ Note: Answers for diagram-based questions (e.g., labels, figures) are based on standard textbook interpretations, as original images were not available. Some questions like "fill flowchart" or "label A, B, C, D" without image are answered with typical values.
📌 Quick reference – plant hormones & functions
| Hormone | Function |
|---|---|
| Auxin | Induction of parthenocarpy |
| Gibberellin | Increases stem length (sugarcane) |
| Cytokinin | Overcomes apical dominance |
| Ethylene | Ripening of fruits |
✅ All answers compiled from the PDF. For questions with missing diagrams, representative scientific answers are given.
Answer key · prepared for IMG_20260316_163932.pdf · complete version