NCERT Solutions for Class 7 Science (Curiosity) Chapter 10: Life Processes in Plants (NCERT 2026–27)

These Class 7 Science Curiosity Chapter 10 solutions cover Life Processes in Plants from the new NCF-2023 textbook (2026–27). The chapter explains how plants make their own food by photosynthesis, how water, minerals and food are transported through the xylem and phloem, and how plants respire. Below you will find every “Let Us Enhance Our Learning” question reproduced verbatim and solved in clear, exam-ready language.

Class: 7 Subject: Science Book: Curiosity Chapter: 10 Topic: Photosynthesis, Transport & Respiration Session: 2026–27
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Class 7 Science Curiosity Chapter 10 Solutions – Overview

Chapter 10 of Curiosity, Life Processes in Plants, answers a simple question: if animals eat food to grow, how do plants get theirs? Through Activities 10.1 to 10.8 the chapter shows that plants need sunlight, water, carbon dioxide and chlorophyll to prepare their own food. Leaves are the ‘food factories’ of a plant, where the green pigment chlorophyll uses light energy to convert carbon dioxide and water into glucose, releasing oxygen — the process called photosynthesis. Tiny pores called stomata on the leaf surface allow the exchange of gases. The chapter then explains transport: water and minerals rise from the roots through the xylem, while food made in the leaves travels through the phloem. Finally it shows that plants, like all living things, respire — breaking down glucose using oxygen to release carbon dioxide, water and energy for growth.

Key Concepts & Definitions

Photosynthesis: the process by which green plants prepare their own food (glucose) using carbon dioxide and water in the presence of sunlight and chlorophyll, releasing oxygen.

Chlorophyll: the green pigment in leaves that captures sunlight efficiently and is essential for preparing starch.

Starch test: the iodine test; a leaf containing starch turns blue-black when iodine solution is added.

Stomata: tiny pores on the surface of leaves that help in the exchange of gases (carbon dioxide and oxygen).

Xylem: thin tube-like structures that transport water and minerals upward from the roots to the leaves and other parts.

Phloem: thin tube-like structures that transport food prepared in the leaves to all parts of the plant.

Respiration: the process in which glucose is broken down in the presence of oxygen to release carbon dioxide, water and energy.

Word equations:
Photosynthesis: Carbon dioxide + Water →(sunlight, chlorophyll) Glucose + Oxygen
Respiration: Glucose + Oxygen → Carbon dioxide + Water + Energy

“Let Us Enhance Our Learning” — NCERT Solutions

All questions below are reproduced verbatim from the NCERT Curiosity textbook (Grade 7). Answers are original and written in exam-ready style.

1. Complete the following table.

ANSWER
S.No.FeaturePhotosynthesisRespiration
1.Raw materialsCarbon dioxide and water (with sunlight and chlorophyll)Glucose and oxygen
2.ProductsGlucose (carbohydrate) and oxygenCarbon dioxide, water and energy
3.Word equationCarbon dioxide + Water →(sunlight, chlorophyll) Glucose + OxygenGlucose + Oxygen → Carbon dioxide + Water + Energy
4.ImportancePrepares food for the plant and releases oxygen into the air for other living beings.Releases energy from food that the plant uses for its growth and development.

2. Imagine a situation where all the organisms that carry out photosynthesis on the earth have disappeared. What would be the impact of this on living organisms?

ANSWER Photosynthetic organisms are the primary producers of food and oxygen on Earth. If they all disappeared: (i) No food source: Plants make food for themselves and for all animals (directly or indirectly). Without them, herbivores would have nothing to eat, and carnivores that depend on herbivores would also starve. The whole food chain would collapse. (ii) Fall in oxygen: Photosynthesis is the main process that releases oxygen into the air. Oxygen levels would slowly drop, making breathing difficult for animals and humans. (iii) Rise in carbon dioxide: Carbon dioxide released by respiration and other processes would no longer be used up, so its level in the air would keep increasing, disturbing the balance of nature. In short, almost all life on Earth would eventually be unable to survive.

3. A potato slice shows the presence of starch with iodine solution. Where does the starch in potatoes come from? Where is the food synthesised in the plant, and how does it reach the potato?

ANSWER Source of the starch: The starch in a potato comes from the food prepared by the plant during photosynthesis. The glucose made by the plant is converted into starch and stored. Where food is made: Food is synthesised mainly in the leaves — the ‘food factories’ of the plant — where chlorophyll uses sunlight, carbon dioxide and water to make glucose. How it reaches the potato: The food made in the leaves is carried to other parts of the plant through the phloem. A potato is an underground stem in which this transported food is stored as starch.

4. Does the broad and flat structure of leaves make plants more efficient for photosynthesis? Justify your answer.

ANSWER Yes, the broad and flat shape of leaves makes plants more efficient at photosynthesis. (i) A broad, flat surface exposes a large area to sunlight, so the leaf can capture maximum light energy. (ii) The flat shape allows sunlight to reach more of the chlorophyll present in the leaf. (iii) The thin, broad surface also has many stomata, helping the leaf take in plenty of carbon dioxide for photosynthesis. Thus, the broad and flat structure helps the leaf absorb more sunlight and carbon dioxide, making food preparation faster and more efficient.

5. X is broken down using Y to release carbon dioxide, Z, and energy.

X + Y → Carbon dioxide + Z + Energy

X, Y, and Z are three different components of the process. What do X, Y, and Z stand for?

ANSWER The given word equation describes the process of respiration: Glucose + Oxygen → Carbon dioxide + Water + Energy Comparing with the equation given: X = Glucose (the food that is broken down) Y = Oxygen (used to break down glucose) Z = Water (released along with carbon dioxide and energy)

6. Krishna set-up an experiment with two potted plants of same size and placed one of them in sunlight and the other in a dark room, as shown in Fig. 10.10. Answer the following questions —

(i) What idea might she be testing through this experiment?

(ii) What are the visible differences in plants in both the conditions?

(iii) According to you, leaves of which plants confirm the iodine test for the presence of starch?

ANSWER (i) Krishna is testing the idea that sunlight is essential for photosynthesis (the preparation of food/starch) and for healthy growth in plants. (ii) The plant kept in sunlight grows well — it is taller, has more leaves and the leaves are healthy and green. The plant kept in the dark grows poorly — it is weak, has fewer leaves and the leaves turn pale or yellowish. (iii) The leaves of the plant kept in sunlight will confirm the iodine test (turn blue-black), because starch is formed only when sunlight is available. The leaves of the plant kept in the dark will not turn blue-black, as no starch is made there.

7. Vani believes that ‘carbon dioxide is essential for photosynthesis’. She puts an experimental set-up, as shown in Fig. 10.11, to collect evidence to support or reject her idea. Answer the following questions —

(i) In which plant(s) in the above set-up(s) will starch be formed?

(ii) In which plant(s) in the above set-up(s) will starch not be formed?

(iii) In which plant(s) in the above set-up(s) will oxygen be generated?

(iv) In which plant(s) in the above set-up(s) will oxygen not be generated?

ANSWER The four set-ups are: (a) Sunlight with carbon dioxide, (b) Sunlight without carbon dioxide, (c) Dark with carbon dioxide, and (d) Dark without carbon dioxide. Photosynthesis (which forms starch and releases oxygen) needs both sunlight and carbon dioxide together. (i) Starch will be formed only in plant (a) — sunlight with carbon dioxide, because both requirements are present. (ii) Starch will not be formed in plants (b), (c) and (d) — each lacks sunlight, carbon dioxide, or both. (iii) Oxygen will be generated only in plant (a), since oxygen is released only when photosynthesis takes place. (iv) Oxygen will not be generated in plants (b), (c) and (d), as photosynthesis cannot occur in them.

8. Ananya took four test tubes and filled three-fourth of each test tube with water. She labelled them A, B, C, and D (Fig. 10.12). In test tube A, she kept a snail; in test tube B, she kept a water plant; in test tube C, she kept both a snail and a plant. In test tube D, she kept only water. Ananya added a carbon dioxide indicator to all the test tubes. She recorded the initial colour of water and observed if there are any colour changes in the test tubes after 2–3 hours. What do you think she wants to find out? How will she know if she is correct?

ANSWER What she wants to find out: Ananya wants to find out how living organisms affect the level of carbon dioxide in water — that animals (the snail) release carbon dioxide during respiration, while plants use up carbon dioxide during photosynthesis, and how the two together balance each other. How she will know (using the carbon dioxide indicator, kept in light): Test tube A (snail only): The snail respires and releases carbon dioxide, so the indicator shows a rise in carbon dioxide. Test tube B (plant only): The plant uses up carbon dioxide for photosynthesis, so the indicator shows a fall in carbon dioxide. Test tube C (snail and plant): The carbon dioxide released by the snail is used by the plant for photosynthesis, so the level stays nearly balanced and the indicator shows little or no change. Test tube D (water only): This is the control; with no organism, the indicator shows no change. By comparing the colour changes with this control, Ananya can confirm her idea.

9. Design an experiment to observe if water transportation in plants is quicker in warm or cold conditions.

ANSWER Aim: To find out whether water moves up a plant faster in warm or in cold conditions. Materials: Two tumblers, water, red ink, and two similar tender twigs with white flowers (such as white sadabahar or balsam). Method: (1) Take two tumblers labelled A and B, and fill each one-third with water. (2) Add a few drops of red ink to both tumblers so the rising water can be seen. (3) Obliquely cut the stems of the two similar twigs at their base and place one twig in each tumbler. (4) Keep tumbler A in a warm place (for example, in sunlight) and tumbler B in a cold place. Keep everything else — type and size of plant, amount of water, and ink — the same so it is a fair test. Observation: After some time, observe how far the red colour has risen in the stem, leaves and flowers of each twig. Result: The twig in which the red colour rises faster and reaches higher shows quicker water transport. This tells us whether warm or cold conditions speed up the movement of water in plants.

10. Photosynthesis and respiration are essential to maintain balance in nature. Discuss.

ANSWER Photosynthesis and respiration are like two opposite processes that keep the gases in the air balanced. During photosynthesis, plants take in carbon dioxide and release oxygen. During respiration, all living beings (including plants) take in oxygen and release carbon dioxide. So the oxygen given out in photosynthesis is used by living things for respiration, and the carbon dioxide given out in respiration is used by plants for photosynthesis. This continuous exchange keeps the amounts of oxygen and carbon dioxide in the air fairly constant. It also keeps food and energy flowing through nature. In this way, photosynthesis and respiration together maintain the balance of gases and life in the environment.

Extra Practice Questions

Short Answer Type Questions

Q1. Why are leaves called the ‘food factories’ of plants?

ANSWERLeaves contain chlorophyll, which uses sunlight to prepare food (starch) from carbon dioxide and water by photosynthesis. Since most of the plant’s food is made here, leaves are called the ‘food factories’ of plants.

Q2. What is the role of stomata in a leaf?

ANSWERStomata are tiny pores on the surface of leaves. They help in the exchange of gases — allowing carbon dioxide in for photosynthesis and letting oxygen and water vapour out.

Q3. Why is a leaf decolourised (made colourless) before performing the starch test?

ANSWERDecolourising removes the green colour of the leaf so that the blue-black colour formed in the iodine test can be seen clearly, making the presence of starch easy to observe.

Q4. State the difference between the functions of xylem and phloem.

ANSWERThe xylem transports water and minerals upward from the roots to the leaves and other parts. The phloem transports food prepared in the leaves to all parts of the plant.

Q5. Why does lime water turn milky in the test tube connected to the flask containing germinating seeds?

ANSWERThe germinating seeds respire and release carbon dioxide. This extra carbon dioxide passes into the lime water and turns it milky, showing that respiration is taking place in the seeds.

Long Answer Type Questions

Q1. Describe the process of photosynthesis, naming the raw materials, products and conditions required.

ANSWERPhotosynthesis is the process by which green plants prepare their own food. The raw materials are carbon dioxide (taken from the air through stomata) and water (absorbed by the roots and carried up through the xylem). The conditions required are sunlight and the green pigment chlorophyll present in the leaves. Using light energy, chlorophyll converts carbon dioxide and water into glucose, a simple carbohydrate, and oxygen is released. The word equation is: Carbon dioxide + Water →(sunlight, chlorophyll) Glucose + Oxygen. The glucose acts as an instant source of energy and is later converted into starch for storage. Photosynthesis takes place mainly in the leaves, but it also occurs in other green parts of the plant that contain chlorophyll.

Q2. How can you experimentally show that carbon dioxide is necessary for photosynthesis (Activity 10.4)?

ANSWERFirst, keep a potted green plant in the dark for two to three days to destarch it (remove stored starch). Take a wide-mouthed bottle and pour some caustic soda (sodium hydroxide) into it, because caustic soda absorbs carbon dioxide from the air (a teacher should handle this chemical). Insert half of one destarched leaf into the bottle through a split cork, leaving the other half outside. Place the set-up in sunlight for a few hours. Then test the leaf for starch using the iodine test. The part of the leaf outside the bottle turns blue-black (starch present), while the part inside the bottle does not turn blue-black, because the caustic soda absorbed the carbon dioxide so no food could be made there. This shows that carbon dioxide is essential for photosynthesis.

Q3. Explain how water and food are transported in a plant, and how this can be shown by an experiment.

ANSWERWater and minerals are absorbed by the roots and carried upward to the leaves and other parts through thin tube-like structures called the xylem. The food prepared in the leaves during photosynthesis is carried to all parts of the plant, including seeds and roots, through another set of tube-like structures called the phloem. Water transport can be shown by Activity 10.7: take two tumblers of water, add red ink to one, and place a similar tender twig (with white flowers) in each, cutting the stems obliquely. The next day, the twig kept in red-coloured water shows red colour in its stem, leaves and flowers. On cutting the stem and viewing it with a magnifying glass, the red colour is seen in the xylem, proving that water (and the dissolved minerals) moves up through the xylem.

MCQs & Assertion–Reason

1. The green pigment in leaves that captures sunlight is called:

(a) starch    (b) chlorophyll    (c) glucose    (d) iodine

2. The presence of starch in a leaf is shown when iodine solution turns it:

(a) red    (b) green    (c) blue-black    (d) colourless

3. During photosynthesis, plants take in ______ and release ______.

(a) oxygen; carbon dioxide    (b) carbon dioxide; oxygen    (c) nitrogen; oxygen    (d) water; nitrogen

4. The food prepared during photosynthesis is in the form of:

(a) protein    (b) fat    (c) glucose    (d) vitamin

5. Tiny pores on the surface of leaves that help in the exchange of gases are called:

(a) xylem    (b) phloem    (c) stomata    (d) chlorophyll

6. Water and minerals are transported in a plant through the:

(a) phloem    (b) xylem    (c) stomata    (d) leaves

7. Food prepared in the leaves is transported to other parts through the:

(a) xylem    (b) roots    (c) phloem    (d) stomata

8. In Activity 10.4, caustic soda is used because it:

(a) gives out oxygen    (b) absorbs carbon dioxide from the air    (c) adds water    (d) provides sunlight

9. During respiration in plants, glucose is broken down to release:

(a) only oxygen    (b) carbon dioxide, water and energy    (c) only starch    (d) chlorophyll

10. The gas that makes a lit matchstick burn with an intense flame (Activity 10.5) is:

(a) carbon dioxide    (b) nitrogen    (c) oxygen    (d) water vapour

Answer key: 1-(b), 2-(c), 3-(b), 4-(c), 5-(c), 6-(b), 7-(c), 8-(b), 9-(b), 10-(c).

For each Assertion–Reason question, choose: (A) Both true and the Reason correctly explains the Assertion; (B) Both true but the Reason is not the correct explanation; (C) Assertion true, Reason false; (D) Assertion false, Reason true.

A-R 1. Assertion: Leaves are called the ‘food factories’ of plants.

Reason: Leaves contain chlorophyll, which prepares starch in the presence of sunlight.

A-R 2. Assertion: A plant kept in the dark cannot prepare starch.

Reason: Sunlight is essential for the process of photosynthesis.

A-R 3. Assertion: Oxygen is released during photosynthesis.

Reason: Plants use oxygen to break down glucose during respiration.

A-R 4. Assertion: Water and minerals are carried up the plant through the phloem.

Reason: The phloem transports food prepared in the leaves to all parts of the plant.

A-R 5. Assertion: All parts of a plant, green or non-green, carry out respiration.

Reason: Respiration releases energy that the plant uses for growth and development.

Answer key: 1-(A), 2-(A), 3-(B), 4-(D), 5-(A).

Quick Revision Summary

  • Plants need sunlight and water for growth (Activity 10.1).
  • Photosynthesis = Carbon dioxide + Water →(sunlight, chlorophyll) Glucose + Oxygen.
  • Leaves are the ‘food factories’; chlorophyll is essential for making starch, shown blue-black by the iodine test.
  • Carbon dioxide (Activity 10.4) and sunlight are both needed for starch formation; oxygen is released (Activity 10.5).
  • Stomata on the leaf surface allow the exchange of gases.
  • Xylem carries water and minerals up; phloem carries food from leaves to all parts.
  • Respiration: Glucose + Oxygen → Carbon dioxide + Water + Energy; all parts of the plant respire.

Common Mistakes to Avoid

Watch out for these

  • Mixing up xylem (water and minerals, upward) with phloem (food, all directions).
  • Thinking plants only photosynthesise and do not respire — plants respire all the time, day and night.
  • Saying the iodine test colour is “blue” — the correct colour for starch is blue-black.
  • Forgetting that both sunlight and carbon dioxide are needed for starch; one alone is not enough.
  • Confusing the two word equations — photosynthesis makes glucose and oxygen; respiration uses them.
  • Thinking only leaves can photosynthesise — any green part with chlorophyll can.

How to score full marks in this chapter

Learn the two word equations exactly and be ready to write them. For activity-based questions, always state which factor is being tested, what is kept the same (fair test), and what the result shows. Remember the iodine test gives a blue-black colour for starch, that the xylem carries water up and the phloem carries food everywhere, and that stomata handle gas exchange. Use the chapter’s own examples — the destarched leaf, the red-ink twig, the germinating seeds and lime water — to show you have read the chapter.

Frequently Asked Questions

What is Class 7 Science Curiosity Chapter 10 about?

Chapter 10, Life Processes in Plants, explains how plants make their own food by photosynthesis using sunlight, water, carbon dioxide and chlorophyll, how water and food are transported through the xylem and phloem, and how plants respire to release energy.

What is the word equation for photosynthesis?

Carbon dioxide + Water, in the presence of sunlight and chlorophyll, gives Glucose + Oxygen. The glucose is later stored as starch and oxygen is released into the air.

What is the difference between xylem and phloem?

The xylem transports water and minerals upward from the roots to the leaves, while the phloem transports the food prepared in the leaves to all parts of the plant.

Are these Class 7 Science Curiosity Chapter 10 solutions free?

Yes. All solutions are free and follow the official NCERT Curiosity textbook for 2026–27.

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