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Life Processes in Plants – Class 7 Science notes, important questions and MCQs

NCERT Class 7 Science, chapter 10. Notes, key terms, important questions with answers and MCQs.

Chapter overview

Plants make their own food by photosynthesis, take in water and minerals through roots, transport them through tissues, and lose water by transpiration.

Food making

Photosynthesis: carbon dioxide + water —sunlight, chlorophyll→ glucose + oxygen.
Leaves are the food factories; stomata let gases in and out.
Starch test: iodine turns blue-black where starch is present.

Transport and respiration

Roots absorb water and minerals; xylem carries them up; phloem carries food to all parts.
Transpiration: loss of water vapour through stomata; it pulls water up and cools the plant.
Plants also respire, day and night, using oxygen and releasing carbon dioxide.

Key terms

Chlorophyll: green pigment that traps sunlight
Stomata: tiny pores on leaves for gas exchange
Transpiration: loss of water vapour from leaves

Formulas

CO₂ + H₂O → glucose + O₂ (sunlight, chlorophyll)

Important questions with answers

Write the word equation for photosynthesis.2 marks

Carbon dioxide + water → (sunlight, chlorophyll) → glucose + oxygen.

How do water and minerals reach the leaves from the roots?3 marks

Roots absorb water and minerals from the soil. Xylem tubes carry them up through the stem to the leaves, helped by the pull created by transpiration.

Describe an activity to show that sunlight is needed for photosynthesis, and give three ways in which transpiration is useful to the plant.5 marks

Keep a potted plant in the dark for 2–3 days to use up its starch. Cover part of a leaf on both sides with black paper and keep the plant in sunlight for a day. Pluck the leaf, boil it in alcohol to remove chlorophyll, rinse and add iodine. The uncovered part turns blue-black (starch made); the covered part does not, showing sunlight is needed. Transpiration creates a pull that helps lift water and minerals, cools the plant, and removes extra water.

Quick revision

Leaves make food.
Xylem = water up; phloem = food around.
Iodine test shows starch.

Exam tips

Variegated leaves make starch only in green parts.
Photosynthesis happens only in light; respiration happens all the time.

Practice MCQs

The green pigment in leaves is
1. chlorophyll
2. haemoglobin
3. melanin
4. carotene only
Show answer
Answer: (a) chlorophyll. Chlorophyll.
Gas released during photosynthesis is
1. oxygen
2. carbon dioxide
3. nitrogen
4. hydrogen
Show answer
Answer: (a) oxygen. Oxygen.
Water moves up in a plant through
1. xylem
2. phloem
3. stomata
4. root hair only
Show answer
Answer: (a) xylem. Xylem.
Iodine solution turns blue-black when it meets
1. protein
2. water
3. fat
4. starch
Show answer
Answer: (d) starch. Starch test.
Plants take in carbon dioxide through
1. stomata
2. roots
3. flowers
4. bark only
Show answer
Answer: (a) stomata. Tiny pores in leaves.
A plant kept in the dark for two days has leaves without starch because
1. it stopped respiring
2. roots stopped
3. no photosynthesis took place and stored starch was used up
4. leaves fell
Show answer
Answer: (c) no photosynthesis took place and stored starch was used up. Destarching.
Transpiration helps the plant by
1. making food
2. storing starch
3. pulling water up and cooling the leaves
4. releasing CO₂ only
Show answer
Answer: (c) pulling water up and cooling the leaves. Transpiration pull.
A potted plant covered with a polythene bag shows water drops inside due to
1. transpiration
2. photosynthesis
3. respiration only
4. germination
Show answer
Answer: (a) transpiration. Water vapour from leaves.

All chapters of Class 7 Science

Written by Kundali IQ from standard, well-established facts to help with revision. This is not an official NCERT publication; always read your textbook too.