Extra Questions for Class 7 Science Chapter 10: Life Processes in Plants

Fresh practice questions for Class 7 Science Chapter 10 “Life Processes in Plants”, reinforcing photosynthesis, respiration, and transportation concepts. These Class 7 Science Chapter 10 important questions are handy for last-minute exam practice.

Q1.

Why does a plant kept in the dark for several days eventually turn pale/yellow?

Answer: Without sunlight, the plant cannot carry out photosynthesis, so it cannot produce the food (glucose/starch) it needs. Chlorophyll production also decreases without light, causing leaves to lose their green colour and turn pale yellow.

Q2. Assertion-Reason

Assertion (A): Lime water turns milky when germinating seeds respire inside a closed flask.
Reason (R): Respiration in seeds releases carbon dioxide, and lime water reacts with carbon dioxide to form a milky precipitate.

Answer: Both A and R are true, and R correctly explains A.

Q3.

Write the balanced word equation for photosynthesis.

Answer: Carbon dioxide + Water → (in presence of sunlight and chlorophyll) → Glucose + Oxygen.

Q4. Spot the error

A student wrote: “Stomata are found only on the stem of a plant and help absorb water.” Identify and correct the error.

Answer: Incorrect. Stomata are mainly found on the leaves (typically the lower surface), and their main function is to allow the exchange of gases (CO2 in, O2 and water vapour out) — not to absorb water.

Q5. HOTS

A gardener notices that a potted plant wilts faster on a hot, windy day than on a cool, still day, even with the same amount of watering. Explain why, linking this to the plant’s transport system.

Answer: Heat and wind increase the rate of transpiration (water loss through stomata), so the plant loses water faster than its xylem can transport replacement water up from the roots. This water deficit causes the plant to wilt faster on a hot, windy day.

Q6.

Why is it important for a leaf to have both chlorophyll and access to carbon dioxide for starch to be produced, based on the caustic soda experiment (Activity 10.4)?

Answer: The experiment shows that even when chlorophyll and sunlight are present, if carbon dioxide is removed (absorbed by caustic soda), no starch forms. This proves carbon dioxide is an essential raw material for photosynthesis, not just chlorophyll and light.

Q7.

Explain why potato is a good storage organ for starch, based on how photosynthesis products move through a plant.

Answer: Glucose made during photosynthesis in the leaves is converted to starch and transported through the plant’s vascular tissue to storage organs like the potato tuber (an underground stem), where it accumulates as a food reserve for the plant to use later.

Q8.

Two identical plants are given equal water, but Plant A is kept in bright sunlight and Plant B in a dimly lit room. After two weeks, which plant is likely to have more stored starch, and why?

Answer: Plant A, because it receives more sunlight for photosynthesis, allowing it to produce more glucose (and hence more stored starch) than Plant B, which has limited light for photosynthesis.

Q9.

Explain the difference between photosynthesis and respiration in plants.

Answer: Photosynthesis occurs only in green (chlorophyll-containing) parts of the plant, only in the presence of light, uses carbon dioxide and water to make glucose, and releases oxygen. Respiration occurs in all living plant cells at all times (day and night), uses oxygen to break down glucose for energy, and releases carbon dioxide and water.

Q10.

Why do gardeners sometimes loosen the soil around plant roots?

Answer: Loosening the soil improves aeration, allowing roots better access to oxygen for respiration, and also makes it easier for roots to absorb water and minerals, both of which support the plant’s growth and transport processes.

See also: NCERT Solutions for Class 7 Science Chapter 10

Revision Notes: Revision Notes for Class 7 Science Chapter 10

Written by Satish

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