NCERT Class 7 Science Chapter 10 Life Processes in Plants

NCERT Class 7 Science Chapter 10 Life Processes in Plants Solutions to each chapter is provided in the list so that you can easily browse through different chapters NCERT Class 7 Science Chapter 10 Life Processes in Plants and select need one. NCERT Class 7 Science Chapter 10 Life Processes in Plants Question Answers Download PDF. NCERT Class 7 Science Solutions.

NCERT Class 7 Science Chapter 10 Life Processes in Plants

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Also, you can read the NCERT book online in these sections Solutions by Expert Teachers as per Central Board of Secondary Education (CBSE) Book guidelines. CBSE Class 7 Science Solutions are part of All Subject Solutions. Here we have given NCERT Class 7 Science Solutions and Textbook for All Chapters, You can practice these here.

Life Processes in Plants

Chapter: 10

Page No – 139

Table 10.1: Effect of sunlight and water on plant growth.

Ans: 

Page No – 144

Table 10.3: Role of air in the preparation of starch by plants.

Ans: 

1. Complete the following table.

Ans: 

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?

Ans: All the organisms that carry out photosynthesis disappeared, it would have a huge impact on life on Earth. 

(i) Loss of oxygen: Photosynthesis is responsible for producing oxygen. Without plants, algae, and other photosynthetic organisms, oxygen levels in the air would slowly decrease, making it hard for most animals, including humans, to breathe.

(ii) No food for most organisms: Plants and algae form the base of the food chain. Without them, there would be no food for herbivores, which means no food for carnivores either. This would lead to the collapse of ecosystems and widespread extinction of species.

(iii) Climate change: Photosynthesizing organisms also absorb carbon dioxide. Without them, CO₂ would build up in the atmosphere, causing more global warming and climate instability, which would make life even harder 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?

Ans: The starch present in a potato slice comes from the process of photosynthesis, which takes place in the green leaves of the plant. During photosynthesis, the leaves use sunlight, carbon dioxide from the air, and water from the soil to produce glucose, a simple sugar. Some of this glucose is used immediately by the plant for energy, while the rest is converted into starch for storage. This starch is then transported through special tubes in the plant, called phloem, from the leaves to different storage organs, such as the potato tuber. As a result, the potato stores starch, which is why it gives a blue-black color when iodine solution is added.

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

Ans: Yes, the broad and flat structure of leaves does make plants more efficient at photosynthesis. Because leaves are wide and flat, they can catch more sunlight, which is needed to make food for the plant. This big surface also helps the leaf take in more carbon dioxide from the air. So, with more sunlight and more carbon dioxide, the plant can make more food through photosynthesis. That’s why having broad and flat leaves helps plants grow better and stay healthy.

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?

Ans: Given equation:

X + Y → Carbon dioxide + Z + Energy

The components stand for the following:

X = Glucose (the food that is broken down)

Y = Oxygen (used to break down glucose)

Z = Water (a byproduct of the breakdown)

So, the complete reaction is:

Glucose + Oxygen → Carbon dioxide + Water + Energy

This is the process of aerobic respiration.

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? 

Ans: Krishna might be testing the idea that sunlight is necessary for photosynthesis. Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to produce their own ¹ food (glucose, which is stored as starch) and oxygen. By placing one plant in sunlight and the other in complete darkness, she can observe the effect of the absence of light on the plant’s ability to produce food.

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

Ans: (a) The plant in sunlight will appear healthy, green, and upright.

(b) The plant in the dark room may appear weak, pale or yellowish (due to lack of chlorophyll production), and may show stunted growth.

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

Ans: The leaves of the plant kept in sunlight will confirm the iodine test for the presence of starch. When tested with iodine solution, these leaves will turn blue-black, indicating that starch is present.This is because photosynthesis occurs only in the presence of sunlight, and starch is a product of photosynthesis.

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? 

Ans: Starch will be formed in the plant in set-up (a) Sunlight with carbon dioxide. Photosynthesis, which produces glucose (later stored as starch), requires both sunlight and carbon dioxide.

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

Ans: Starch will not be formed in the plants in set-ups (b), (c), and (d):

(b) Sunlight without carbon dioxide – carbon dioxide is missing, so photosynthesis cannot occur.

(c) Dark with carbon dioxide – sunlight is absent, so no photosynthesis.

(d) Dark without carbon dioxide – both essential components are missing, hence no photosynthesis and no starch formation.

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

Ans: Oxygen will be generated in the plant in set-up (a) Sunlight with carbon dioxide. Oxygen is a byproduct of photosynthesis, which occurs when plants have access to both sunlight and carbon dioxide.

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

Ans: Oxygen will not be generated in the plants in set-ups (b) Sunlight without carbon dioxide, (c) Dark with carbon dioxide, and (d) Dark without carbon dioxide. Similar to starch formation, oxygen production through photosynthesis is dependent on the availability of both carbon dioxide and sunlight. The absence of either of these essential components prevents photosynthesis and thus the release of oxygen.

8. Ananya took four test tubes and fi lled 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? 

Ans: Ananya wants to find out how respiration and photosynthesis affect the carbon dioxide levels in water. She uses a carbon dioxide indicator to observe these changes in different conditions:

(i) Test tube A (snail only): CO₂ increases due to respiration; indicator changes to a color showing high CO₂.

(ii) Test tube B (plant only): CO₂ decreases due to photosynthesis; indicator changes to a color showing low CO₂, if light is present.

(iii) Test tube C (snail + plant): Shows the net effect of both processes; color depends on which process dominates.

(iv) Test tube D (water only): Acts as a control; minimal or no change expected.

By comparing the color changes in each test tube, Ananya can confirm whether her understanding of the role of plants and animals in CO₂ balance is correct.

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

Ans: Experiment: To compare the rate of water transportation in warm and cold conditions.

Materials Required:

(i) 2 similar small leafy plants or freshly cut leafy shoots (e.g., from a balsam plant).

(ii) 2 beakers.

(iii) Water.

(iv) Red food colouring or coloured ink.

(v) A warm place (e.g., sunlight or near a lamp).

(vi) A cool place (e.g., near a fan or in a refrigerator).

(vii) Stopwatch or clock.

(viii) Thermometer (optional).

Procedure:

(i) Fill both beakers with equal amounts of water and add a few drops of red food colouring to each.

(ii) Place one plant in each beaker, ensuring the stems are fully submerged.

(iii) Keep Beaker A in a warm place (sunlight or near a lamp).
Keep Beaker B in a cool place (shaded area or near a fan).

(iv) Leave both setups undisturbed for the same amount of time (e.g., 2–3 hours).

(v) Observe and measure how far the coloured water has travelled up the stem in each plant.

Observation:

Measure the height of coloured water in the stem of both plants.Record which plant shows faster upward movement of water.

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

Ans: Photosynthesis and respiration are two essential processes that help maintain the balance of nature. In photosynthesis, green plants use sunlight to prepare food by taking in carbon dioxide from the air and releasing oxygen as a by-product. This oxygen is used by humans and animals during respiration, a process in which they break down food to release energy, and in turn, release carbon dioxide back into the atmosphere. Thus, while photosynthesis removes carbon dioxide from the air and adds oxygen, respiration does the opposite. These two processes form a natural cycle that keeps the levels of oxygen and carbon dioxide in balance. Without this balance, life on Earth would not be sustainable, as neither plants nor animals could survive properly.Hence, photosynthesis and respiration are vital for the survival of living beings and for maintaining environmental stability.

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