• Observation: Spot only when holes aligned; no spot if misaligned.
• Reason: Light travels straight.

• Observation: Flame visible in straight pipe, not bent.
• Reason: Light travels straight, can't bend around corners.

(i) Green plants are called (a) autotrophs

(ii) The process by which plants make their food is (c) photosynthesis

(iii) The tiny pores present on the surface of leaves are called (b) stomata

(iv) The tissue that transports food in plants is (c) phloem

(v) Loss of water in the form of vapour from aerial parts of the plant is known as (a) transpiration

(i) Plants take carbon dioxide from air through stomata.

(ii) The green pigment in leaves is chlorophyll.

(iii) Water is transported in plants through xylem.

(iv) Cuscuta is an example of a parasite.

(v) Pitcher plant is an insectivorous plant.

(i) Food-making process in plants → photosynthesis

(ii) Green pigment that traps sunlight → chlorophyll

(iii) Loss of water vapour from leaves → transpiration

(iv) Plant that traps insects → insectivorous

(v) Relationship where both organisms benefit → symbiosis

(i) Plants need sunlight and water for growth. → True

(ii) Photosynthesis takes place only at night. → False (It takes place in the presence of sunlight during the day.)

(iii) Xylem transports food from leaves to other parts. → False (Xylem transports water and minerals; phloem transports food.)

(iv) Transpiration helps in upward movement of water. → True

(v) Mushroom is an autotrophic plant. → False (Mushroom is saprophytic.)

(a) What is photosynthesis?
Photosynthesis is the process by which green plants make their own food using carbon dioxide, water, sunlight, and chlorophyll, releasing oxygen as a by-product.

(b) Write the balanced equation of photosynthesis.
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in the presence of sunlight and chlorophyll).

(c) Why was the plant in Pot C yellow in Activity 10.1?
The plant in Pot C was kept in the dark, so it lacked sunlight. Without sunlight, chlorophyll (green pigment) is not formed or breaks down, making the leaves yellow (chlorosis).

(d) Name two special modes of nutrition in plants.
Parasitic nutrition (e.g., Cuscuta) and insectivorous nutrition (e.g., pitcher plant).

(a) Explain the role of sunlight and water in plant growth with reference to Activity 10.1.
In Activity 10.1, three pots with similar saplings were used:
- Pot A (direct sunlight + water): Showed maximum growth, healthy green leaves, increased height and number of leaves because sunlight is needed for photosynthesis (food making) and chlorophyll formation, while water is essential for photosynthesis, nutrient transport, and maintaining turgidity.
- Pot B (direct sunlight + no water): Poor growth, wilted or dried leaves because lack of water stops photosynthesis and causes loss of turgidity.
- Pot C (dark + water): Yellow leaves, elongated weak stem because no sunlight means no photosynthesis and no chlorophyll, leading to starvation and etiolation.
Conclusion: Both sunlight and water are crucial for healthy plant growth.

(b) Differentiate between xylem and phloem.
Xylem: Transports water and minerals from roots to leaves (upward only); made of dead cells; unidirectional.
Phloem: Transports food (glucose) from leaves to all parts (both directions); made of living cells; bidirectional.

(c) Describe any two special types of nutrition in plants with examples.
1. Parasitic nutrition: Plants without chlorophyll depend on host for food. Example: Cuscuta (amarbel) – twines around host, absorbs nutrients via haustoria.
2. Insectivorous nutrition: Plants trap and digest insects for nitrogen (in nitrogen-poor soil). Example: Pitcher plant – leaf modified into pitcher with lid and digestive juices; insects slip in and are digested.

(i) Leaves are green in colour.
Due to the presence of chlorophyll, a green pigment that absorbs sunlight for photosynthesis.

(ii) Excessive transpiration causes wilting.
Loss of too much water makes plant cells lose turgidity (stiffness), causing leaves and stems to droop.

(iii) Plants kept in dark become yellow.
No sunlight prevents formation of chlorophyll, the green pigment breaks down, leading to yellowing (chlorosis).

(Draw a leaf structure with lower epidermis showing stomata – tiny pore guarded by two bean-shaped guard cells. Label: Stoma, Guard cells, Epidermal cells.)