Plus One Botany Annual Exam Answer Key March 2026

📋 Answer key KMC_20260316_170934

📅 March 16, 2026 🔬 Botany / Zoology

I. Questions 1 – 5 (answer any three)

Q1 Which kingdom includes multicellular, heterotrophic organism with chitin in their cell walls?

Answer: Kingdom Fungi.

Q2 Which plant group has vascular tissues but no seeds? (a) Bryophytes (b) Algae (c) Pteridophytes (d) Gymnosperm

Answer: (c) Pteridophytes.

Q3 The type of venation found in dicot leaves is

Answer: Reticulate venation.

Q4 Meiosis I : Reductional division :: Meiosis II : ______

Answer: Equational division.

Q5 Name the meristem responsible for primary growth of plants.

Answer: Apical meristem.

II. Questions 6 – 16 (answer any nine)

Q6 What causes red tides and what are their effects?

Answer:
- Cause: Rapid increase (bloom) of certain marine dinoflagellates (e.g., Gonyaulax / Karenia brevis).
- Effects: Produce toxins that kill marine life; can cause shellfish poisoning and respiratory irritation in humans.

Q7 What is heterospory? Name two pteridophytes that show these features.

Answer:
Heterospory: Production of two kinds of spores (microspores and megaspores) by the same plant.
Examples: Selaginella and Salvinia.

Q8 Mention two differences between the Vascular bundles of dicot and monocot stems.

Feature	Dicot stem	Monocot stem
Arrangement	Bundles arranged in a ring	Bundles scattered
Cambium	Open bundles (cambium present → secondary growth)	Closed bundles (no cambium → no secondary growth)

Q9 What are bulliform cells? State its functions.

Answer:
Bulliform cells: Large, bubble-like colourless cells in upper epidermis of monocot leaves (grasses).
Functions: Help in unrolling of young leaves; assist in folding/unfolding to reduce water loss.

Q10 Observe the diagram (chloroplast).

(a) Chloroplast
(b) A = Thylakoids / Grana, B = Stroma
(c) 70S ribosomes

Q11 (a) Fill flowchart (endomembrane). (b) Organelle with hydrolytic enzymes?

(a) Blank 1: Endoplasmic Reticulum (ER), Blank 2: Golgi apparatus, Blank 3: Lysosomes, Blank 4: Vacuoles
(b) Lysosome

Q12 PGA as first stable product (C3 plants).

(a) C3 plants
(b) Melvin Calvin
(c) Enzyme: RuBisCO
(d) Primary CO₂ acceptor: Ribulose-1,5-bisphosphate (RuBP)

Q13 (a) Respiratory quotient? (b) Two substrates.

(a) RQ = volume of CO₂ released / volume of O₂ consumed.
(b) Carbohydrates (glucose), Fats (lipids).

Q14 Compounds from Krebs cycle that yield ATP via oxidative phosphorylation.

(a) NADH and FADH₂
(b) ~ 3 ATP from NADH, ~ 2 ATP from FADH₂.

Q15 Match plant hormone with function.

Hormone	Function
Auxin	Induction of parthenocarpy
Gibberellin	Increases length of stem in sugarcane
Cytokinin	Helps overcome apical dominance
Ethylene	Ripening of fruits

Q16 "Plant growth generally is Indeterminate." Evaluate.

Answer: True. Meristematic tissues retain division ability throughout life; plants keep producing new organs – unlike determinate growth in animals.

III. Questions 17 – 20

Q17 Mango fruit diagram (epicarp, mesocarp).

(a) A = Epicarp, B = Mesocarp
(b) Mesocarp nature: Mango = fleshy & juicy; Coconut = fibrous (coir)
(c) Both are drupes. Peculiarity: develops from monocarpellary ovary; stony endocarp (pit); three pericarp layers.

Q18 Cell cycle diagram stages A, B, C.

(a) A = G₁ phase, B = S phase, C = G₂ phase
(b) Haploid cells divide by mitosis in male honeybees (drones)
(c) S phase = DNA synthesis (replication) phase

Q19 C4 plants special anatomy and advantages.

(a) Kranz anatomy
(b) Advantages: 1. High productivity; 2. No photorespiration; 3. Better water use efficiency; 4. Tolerance to high temp/light.

Q20 TCA cycle labelling, scientist, GTP step.

(a) A = Acetyl CoA, B = Citrate, C = α-Ketoglutarate, D = Succinate
(b) Scientist: Sir Hans Krebs
(c) GTP synthesis: conversion of Succinyl‑CoA → Succinate (enzyme succinyl‑CoA synthetase).