Chapter 12 — Plant Anatomy and Plant Physiology: Multiple Choice Questions
1. The tissue responsible for the transport of water and minerals in plants is ______.
Answer
(a) Phloem (b) Xylem (c) Parenchyma (d) Collenchyma
✅ Answer: (b) Xylem
ExplanationXylem transports water and dissolved minerals from roots to leaves (upward). Phloem transports prepared food (glucose/sucrose) from leaves to all parts of the plant (upward and downward). Together, xylem and phloem form the vascular tissue.
2. The raw materials for photosynthesis are ______.
Answer
(a) CO₂ and O₂ (b) CO₂ and H₂O (c) O₂ and glucose (d) H₂O and glucose
✅ Answer: (b) CO₂ and H₂O
ExplanationPhotosynthesis equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂ Raw materials: CO₂ (from air) and H₂O (from soil). Chlorophyll is the pigment that absorbs light energy. Oxygen is the by-product.
3. Stomata are found mainly on the ______ of a leaf.
Answer
(a) Upper surface (b) Lower surface (c) Midrib (d) Petiole
✅ Answer: (b) Lower surface
ExplanationStomata are tiny pores mainly on the lower epidermis of leaves (to reduce water loss from direct sunlight). Each stoma is surrounded by two guard cells that control opening and closing. When guard cells absorb water, they swell and the stoma opens; when they lose water, stoma closes.
4. The process by which plants lose water through stomata is called ______.
Answer
(a) Osmosis (b) Transpiration (c) Photosynthesis (d) Respiration
✅ Answer: (b) Transpiration
ExplanationTranspiration is the loss of water from plants mainly through stomata (also through cuticle and lenticels). It creates a "transpiration pull" that helps draw water upward from roots. Excessive transpiration on hot dry days causes stomata to close (to conserve water).
5. Chlorophyll is found in ______.
Answer
(a) Mitochondria (b) Chloroplasts (c) Nucleus (d) Vacuole
✅ Answer: (b) Chloroplasts
ExplanationChlorophyll is the green pigment located in chloroplasts (found in the mesophyll cells of leaves, and also in stems and other green parts). Chlorophyll absorbs mainly red and blue light for photosynthesis, and reflects green light (which is why plants appear green).
6. The meristematic tissue responsible for increase in length of the plant is ______.
Answer
(a) Lateral meristem (b) Intercalary meristem (c) Apical meristem (d) Vascular cambium
✅ Answer: (c) Apical meristem
Explanation
- Apical meristem: Found at root tips and shoot tips. Responsible for growth in length (primary growth).
- Lateral meristem (cambium): Found in cortex. Responsible for growth in width/girth (secondary growth) — forms wood.
- Intercalary meristem: Found at nodes of grasses. Responsible for elongation after grazing/mowing.
7. Phloem transports ______ in plants.
Answer
(a) Water and minerals (b) Prepared food (sucrose) (c) Carbon dioxide (d) Oxygen
✅ Answer: (b) Prepared food (sucrose)
ExplanationPhloem transports photosynthates — mainly sucrose (sugar), along with amino acids and hormones — from the leaves (source) to all parts of the plant (sink) in a process called translocation. The driving force is an osmotic pressure gradient (Münch pressure-flow hypothesis).
8. Which of the following is not required for photosynthesis?
Answer
(a) Light (b) CO₂ (c) O₂ (d) Chlorophyll
✅ Answer: (c) O₂
ExplanationPhotosynthesis requires: light, CO₂, H₂O, and chlorophyll. Oxygen is a product of photosynthesis (released into the air), not a raw material. In fact, photosynthesis produces O₂ by splitting water molecules.
9. Guard cells help in ______.
Answer
(a) Absorption of water (b) Opening and closing of stomata (c) Transport of food (d) Production of seeds
✅ Answer: (b) Opening and closing of stomata
ExplanationEach stoma is flanked by two guard cells that control its opening and closing:
- When turgid (full of water → daytime, high sugar): guard cells bow outward → stoma opens (for CO₂ entry and O₂ exit for photosynthesis)
- When flaccid (lose water → night, water stress): guard cells straighten → stoma closes (to prevent water loss)
10. The green colour of plants is due to the presence of ______.
Answer
(a) Carotenoids (b) Xanthophylls (c) Chlorophyll (d) Anthocyanins
✅ Answer: (c) Chlorophyll
ExplanationChlorophyll is the primary photosynthetic pigment that gives plants their green colour. It absorbs red and blue light for photosynthesis and reflects green light. Other pigments: carotenoids (orange/yellow, autumn leaves), anthocyanins (red/purple, flowers), xanthophylls (yellow).
Quick Revision
| Tissue | Function |
|---|
| Xylem | Water & mineral transport (upward) |
| Phloem | Food transport (translocation) |
| Parenchyma | Storage, photosynthesis, packing |
| Collenchyma | Mechanical support in young stems |
| Sclerenchyma | Mechanical support in mature plants |
| Meristematic | Cell division, growth |
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