Life Processes in Plants Class 7 Questions and Answers Science Chapter 10

Students can use Curiosity Class 7 Science Book Solutions Chapter 10 Life Processes in Plants Class 7 Question and Answer as a quick reference guide.

Class 7 Science Chapter 10 Life Processes in Animals Question Answer

Science Class 7 Chapter 10 Question Answer Life Processes in Animals

Life Processes in Animals Class 7 Question Answer (InText)

Question 1.
What changes do you notice in plants when they grow? (Page 137)
Answer:
As the plants grow, new leaves and branches emerge, its height increases and its stem thickens.

Question 2.
What causes these changes in plants? (Page 138)
Answer:
Water, sunlight, nutrients from soil, carbon dioxide and chlorophyll help the plants to synthesise their food which helps in the growth of the plant and the changes.

Question 3.
How do plants obtain the food they need to grow? (Page 139)
Answer:
Unlike animals, the plants do not eat the food. They prepare their food (as glucose) from carbon dioxide and water in chlorophyll containing parts in the presence of sunlight. Oxygen is released during this process. Plants store food in the form of starch, a type of carbohydrate.

Question 4.
How does sunlight contribute in the production of starch in plants? (Page 141)
Answer:
Sunlight is necessary to carry out the process of photosynthesis. During photosynthesis, food is produced in the form of glucose, a simple carbohydrate. This glucose is then converted into starch for storage.
Therefore, sunlight provides the energy needed for the plant to convert carbon dioxide and water into glucose, which is subsequently turned into starch. Without sunlight, photosynthesis cannot occur, and thus, starch cannot be produced.

Question 5.
Which gas from the air is essential in the process of food preparation in plants? (Page 143)
Answer:
CO₂
Question 6.
Do plants only take in substances from their surroundings, or do they also release something? (Page 144)
Answer:
Plants carry out photosynthesis to produce glucose in the presence of water, sunlight, carbon dioxide and chlorophyll. During the process oxygen is released by plants.

Question 7.
What part of plants helps in the exchange of carbon dioxide and oxygen? (Page 146)
Answer: Tiny pores called stomata present on the surface of the leaves help in exchange of gases i.e. carbon dioxide and oxygen.

Question 8.
How do water and minerals taken up by the roots move to all parts of the plant? (Page 147)
Answer:
Water and minerals taken up by the roots are transported to the leaves and other parts through thin tube-like structure called xylem.
Question 9.
How does food prepared in the green parts of the plants get transported to other parts of the plant? (Page 148)
Answer:
The food prepared by plants in the leaves is transported thin tube-like structures called phloem.

Question 10.
Do plants respire like us? (Page 149)
Answer:
All parts of a plant, green or non-green, carry out respiration. During respiration, glucose is broken down in the presence of oxygen, releasing carbon dioxide, water and energy. The energy produced during respiration is used by plants for their growth and development.

Question 9.
Design an experiment to observe if water transportation in plants is quicker in warm or cold conditions.
Answer:
Experiment: Effect of Tempe¬rature on Water Transportation in Plants.

Materials required:

1. 2 identical leafy plant stems
2. 2 beakers with the same amount of water
3. Red or blue food colouring sub¬stance
4. A warm place (like near a heater or under sunlight)
5. A cold place (like a refrigerator or icebox)
6. Stopwatch or timer.

Procedure:

1. Add a few drops of food colouring substance to both beakers of water.
2. Place one leafy plant stem in each beaker.
3. Place:
   • Beaker 1 in a warm environment.
   • Beaker 2 in a cold environment.
4. Observe after 2-3 hours
5. How far the coloured water has travelled up the stem in each case?

Observations:
• Observe the height till the coloured water has reached in both the leafy plant stems.

Conclusion:
• There is more movement of coloured water or water transportation in plant kept under warm conditions compared to the plant which has been kept under cold conditions. This indicates that temperature affects water transportation in plants.

Question 10.
Photosynthesis and respiration are essential to maintain balance in nature. Discuss.
Answer:
Photosynthesis and respiration are inter connected but interconnected processes that help maintain the balance of oxygen and carbon dioxide in nature.

Photosynthesis:
• Occurs in green plants in the presence of sunlight.
• Plants take in carbon dioxide (CO₂) and release oxygen (O₂).

This process consumes CO₂ present in the atmosphere and adds O₂, which animals and humans consume during the process of breathing.

Respiration:
• Carried out by all living organisms, including plants and animals.
• They take in oxygen and release carbon dioxide by breaking down food to produce energy.
• Equation: Glucose + Oxygen → Carbon dioxide + Water + Energy

This process increases CO₂, in the atmosphere and uses up O₂

Balance in Nature:

1. Plants absorb the CO₂ released by animals during respiration.
2. Animals use the O₂ released by plants during photosynthesis.
3. This continuous cycle maintains the oxygen-carbon dioxide balance in the atmosphere.
4. Without this balance, life on Earth wouldn’t be possible.

Conclusion: Photosynthesis and respiration are essential for the survival of all living beings and for keeping Earth’s environment stable.

NCERT Class 7 Science Chapter 10 Question Answer Life Processes in Plants (Exercise)

Let Us Enhance Our Learning (Pages 150—152)

Question 1.
Complete the following table.

Answer:

Question 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:
If all organisms that cany out photosynthesis disappeared, there would be no production of oxygen and food for other living organisms. This would disrupt the food chain, as plants provide food for herbivores and oxygen for respiration. Without plants, life on Earth would not be sustained.

Question 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:
The starch in potatoes comes from the glucose produced in the leaves during photosynthesis. Photosynthesis occurs in the leaves, where food is synthesised in the form of glucose. This glucose is then transported through the plant to the potato, where it is stored in the form of starch.

Question 4.
Does the broad and flat structure of leaves make plants more efficient for photosynthesis? Justify your answer.
Answer:
Yes, the broad and flat structure of leaves makes plants more efficient for photosynthesis. This shape increases the surface area, allowing more sunlight to be absorbed by the chlorophyll present in the leaves. It also helps in the exchange of gases through the stomata, thus enhancing the process of photosynthesis.

Question 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:
X – Glucose
Y – Oxygen
Z – Water

Question 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.

Fig. Experimental pots, (a) Sunlight (b) Complete dark

Answer the following questions.
(i) What idea might she be testing through this experiment?
Answer:
Through this experiment, she is testing whether sunlight is necessary for photosynthesis in plants or not.

(ii) What are the visible differences in plants in both the conditions?
Answer:
The plant kept in sunlight looks healthy and green as it performs photosynthesis while the plant kept in the dark room looks weak, pale, and yellowish because it cannot perform photosynthesis properly.

(iii) According to you, leaves of which plants confirm the iodine test for the presence of starch?
Answer:
The leaves of the plant kept in sunlight will confirm the iodine test for starch.

Question 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.

Fig. A potted plant with sufficient water is placed under the prescribed conditions.
(a) Sunlight with carbon dioxide
(b) Sunlight without carbon dioxide
(a) Dark with
(b) Dark without carbon dioxide carbon dioxide

Answer the following questions.
(i) In which plant(s) in the above set-up(s) will starch be formed?
Answer:
Only in plant kept in sunlight with carbon dioxide, starch will be formed.

(ii) In which plant(s) in the above set-up(s) will starch not be formed?
Answer:
In all plants except the plant kept in sunlight with carbon dioxide.

(iii) In which plant(s) in the above set-up(s) will oxygen be generated?
Answer: Oxygen will be generated in a plant kept in sunlight with carbon dioxide.

(iv) In which plant(s) in the above set-up(s) will oxygen not be generated?
Answer:
Except for the plant kept in sunlight with carbon dioxide, oxygen will not be generated in any of the other plants.

Question 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?

Fig. Experimental set-up
Answer:
Ananya wants to find out how plants and animals affect the amount of carbon dioxide in water. She is testing the role of respiration and photosynthesis. The carbon dioxide indicator changes colour depending on how much carbon dioxide is present in the water. Ananya will know she is correct by observing the colour changes in the carbon dioxide indicator in each test tube:

1. Test Tube A (Snail only): The indicator will turn yellow/orange, showing increased carbon dioxide due to the snail’s respiration.
2. Test Tube B (Plant only): The indicator will turn blue/purple, showing decreased carbon dioxide because the plant uses it during photosynthesis.
3. Test Tube C (Snail + Plant): The colour may stay neutral or slightly blue, showing a balance as the snail gives out carbon dioxide and the plant uses it.
4. Test Tube D (Only water): No colour change, as there is no living organism to add or remove carbon dioxide.

Question 9.
Design an experiment to observe if water transportation in plants is quicker in warm or cold conditions.
Answer:
Experiment: Effect of Tempe¬rature on Water Transportation in Plants.

Materials required:

1. 2 identical leafy plant stems
2. 2 beakers with the same amount of water
3. Red or blue food colouring sub¬stance
4. A warm place (like near a heater or under sunlight)
5. A cold place (like a refrigerator or icebox)
6. Stopwatch or timer.

Procedure:

1. Add a few drops of food colouring substance to both beakers of water.
2. Place one leafy plant stem in each beaker.
3. Place:
4. Beaker 1 in a warm environment.
5. Beaker 2 in a cold environment.
6. Observe after 2-3 hours
7. How far the coloured water has travelled up the stem in each case?

Observations:
• Observe the height till the coloured water has reached in both the leafy plant stems.

Conclusion:
• There is more movement of coloured water or water transportation in plant kept under warm conditions compared to the plant which has been kept under cold conditions. This indicates that temperature affects water transportation in plants.

Question 10.
Photosynthesis and respiration are essential to maintain balance in nature. Discuss.
Answer:
Photosynthesis and respiration are inter connected but interconnected processes that help maintain the balance of oxygen and carbon dioxide in nature.
• Photosynthesis:
• Occurs in green plants in the presence of sunlight.
• Plants take in carbon dioxide (CO,) and release oxygen (02).

This process consumes CO₂ present in the atmosphere and adds O₂, which animals and humans consume during the process of breathing.

Respiration:

1. Carried out by all living organisms, including plants and animals.
2. They take in oxygen and release carbon dioxide by breaking down food to produce energy.
3. Equation: Glucose + Oxygen → Carbon dioxide + Water + Energy

This process increases CO₂, in the atmosphere and uses up O₂

Balance in Nature:

1. Plants absorb the CO₂ released by animals during respiration.
2. Animals use the O₂ released by plants during photosynthesis.
3. This continuous cycle maintains the oxygen-carbon di¬oxide balance in the atmosphere.
4. Without this balance, life on Earth wouldn’t be possible.

Conclusion: Photosynthesis and respiration are essential for the survival of all living beings and for keeping Earth’s environment stable.

Class 7 Life Processes in Animals Question Answer (Activities)

Activity 10.1: Effect of Sunlight and Water on Plant Growth (Pages 138—139)

1. Take three earthen pots (or used bottles/containers) of the same size filled with garden soil. Plant saplings of similar sizes of a fast-growing plant like chilli or tomato in each pot (Fig.).
2. Label the pots A, B, and C.
3. Count the number of leaves on each sapling and record your observations.
4. Place pot A in direct sunlight. Keep the soil in this pot slightly moist by adding an adequate amount of water every day (Fig.(a)).
5. Place pot B in direct sunlight, without adding water to the soil (Fig.(b)).
6. Place pot C in the dark. Keep the soil in this pot slightly moist by adding ah adequate amount of water every day (Fig.c).
7. Observe the plants for two weeks and record changes in their height, number of leaves, colour of leaves, and any other changes that may appear.
8. Record your observations in Table 10.1.

(i) What differences did you observe between the plants in the three pots?
(ii) Which pot has the plant with the maximum growth?
(iii) Which pot has the plant with the least growth?

Answer:

Table 10.1: Effects of sunlight and water on plant growth

Pots kept under different conditions	Availability of		Height of plant (cm)		Number of leaves		Colour of Leaves (Green/ Yellow)
	Sunlight	Water	Day 1	After 2 Weeks	Day 1	After 2 Weeks
Pot A: In direct sunlight, with water	Yes	Yes	5	15	4	12	Green leaves
Pot B: In direct sunlight, without water	Yes	No	5	6	4	5	Yellow leaves
Pot C: In the dark, with water	No	No	5	7	4	6	Yellow leaves

(i) Plant in Pot A grew well: tall, green leaves, more new leaves.
Plant in Pot B grew very little: leaves started turning yellow due to lack of water.
Plant in Pot C grew slightly: leaves pale or yellow due to absence of sunlight.

(ii) Plant in Pot A shows maximum growth because it received both sunlight and water.

(iii) Plant in Pot B shows least growth because it had sunlight but no water, leading to poor growth and yellowing of leaves. :

Activity 10.2: Let Us Check (Demonstration Activity) (Pages 140-141)

Fig. Starch test in a leaf, (a) Boiling set-up (b) Iodine test

Observation and Conclusion: If the colour of the leaf changes to blue-black, we can conclude that starch is present in the leaf.

Activity 10.3: Let Us Check (Pages 141-142)

Table 10.2: Presence of starch in green and non-green parts of the leaves of plants

Observation and Conclusion:
• Only the green parts of the leaf can perform photosynthesis and make starch due to the presence of chlorophyll.
• Sunlight is necessary for photosynthesis to occur and for starch to be produced in leaves.

Activity 10.4: Role of Air in The Preparation of Starch by Plants (Pages 143—144)

The teacher may demonstrate this activity.

1. Take a potted green plant and keep it in the dark for two to three days to allow it to destarch (i.e., lose any stored starch). Then, mark one leaf of this plant for this experiment.
2. Take a wide-mouthed bottle and pour some caustic soda (sodium hydroxide) into it (caustic soda absorbs carbon dioxide from the air.)
   • Caution: Caustic soda is a strong chemical that can cause skin burns; only teachers should handle it.
3. Insert half of the destarched leaf into the bottle through a split cork, leaving the other half of the leaf outside, and place the bottle as shown in Fig. (a).
4. Place the set-up in sunlight for a few hours.
5. Observe and record the availability of water, sunlight, chlorophyll, and carbon dioxide in Table 10.3.
6. Remove the leaf and test it for starch using the iodine test, as was done in Activity 10.2.
7. Record your observations in Table 10.3.

Answer:

Part of the leaf	Availability of				Starch present (Yes/No)
	Water	Sunlight	Chlorophyll	Carbon dioxide
Part of the leaf inside the bottle	Yes	Yes	Yes	No	No
Part of the leaf outside the bottle	Yes	Yes	Yes	Yes	Yes

Fig. Testing the role of chlorophyll and air, (a) The set-up (b) Iodine test on the leaf

Observation and Conclusion:
• The part of the leaf that was inside the bottle with caustic soda (sodium hydroxide) did not turn blue-black after the iodine test. This shows that no starch was produced in that part because caustic soda absorbs carbon dioxide, which is needed for photosynthesis.

• The part of the leaf that was outside the bottle turned blue-black, showing that starch was produced because that part had access to carbon dioxide and could perform photosynthesis. This experiment proves that carbon dioxide is necessary for plants to prepare starch.

Activity 10.5: Let Us Explore (Page 145)

Fig. Activity showing the release of oxygen during photosynthesis

(i) What difference do you observe in the two set¬ups?
Answer:
In set-up A (kept in sunlight), we observe bubbles on the inverted test tube. While in set¬up B (kept in the dark), no bubbles are seen.

(ii) Do you observe air bubbles emerging in the inverted test tube in set-up A?
Answer:
Yes, air bubbles are seen rising and collecting in the inverted test tube in set-up A.

(iii) The gas produced in this set-up caused bubbles to emerge and get accumulated in the inverted test tube. Which gas is this?
Answer:
The gas produced is oxygen, which is released during photosynthesis.

Observation and Conclusion:
• When a test tube is taken off the set-up and a lit matchstick is inserted into the tube, it produces an intense flame, which confirms that oxygen gas is released during the process of photosynthesis.

Activity 10.6: Let Us Examine (demonstration activity) (Page 147)

Observation
(i) What do you observe?
Answer:
Tiny pores on the peel of the leaf.

(ii) Do you notice tiny pores on the peel?
Answer:
Yes

Conclusion:
• These tiny pores are stomata. They are prsent on the surface of leaves, help in the exchange of gases.

Fig. Stomata on the lower surface of a rhoeo leaf

Activity 10.7: Let Us Experiment (Page 148)

(a) With water (b) With coloured water plant twigs placed in water with different treatments

Fig. 10.7: Experiment to check for water transportation in plants

Observation and Conclusion:
• This experiment shows that water and minerals are transported through the xylem in plants. Xylem is thin, tube-like structure found in the stem, branches, and leaves, carrying water and minerals from the roots to all parts of the plant.

Activity 10.8: Let Us Find Out (Demonstration Activity) (Page 149)

Fig. Experiment to check for water transportation in plants
(a) With water
(b) With coloured water, plant twigs placed in water with different treatments
(c) With water
(d) With coloured water, plant twigs after one day
(e) Enlarged view of cut end of the twig

Observation and Conclusion:
• This experiment shows that water and minerals are transported through the xylem in plants. Xylem is thin, tube-like structure found in the stem, branches, and leaves, carrying water and minerals from the roots to all parts of the plant.

Activity 10.8: Let Us Find Out (Demonstration Activity) (Page 149)

Fig. Set-up to test respiration in plants

(i) Does the lime water turn milky in both the test tubes?
Answer:
The lime water turn milky only in the test tube connected to the flask.

(ii) Why does the lime water turn milky in the test tube connected to the flask?
Answer:
Lime water turns milky due to the presence of carbon dioxide. This carbon dioxide is produced by the seeds during respiration.

Observation and Conclusion:  Plants also respire like us and release carbon dioxide.