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

Reviewing the Curiosity Class 7 Science Book Solutions Chapter 10 Life Processes in Plants Class 7 Question and Answer before exams can boost your confidence.

Class 7 Science Chapter 10 Life Processes in Plants Question Answer

Science Class 7 Chapter 10 Question Answer Life Processes in Plants

Life Processes in Plants Class 7 Question Answer (InText)

Question 1.
What changes can be observed in a plant during its life span? (Page 137)
Answer:
During its life span, a plant show changes like the growth of new leaves and branches, increase in height, thickening of the stem, flowering and fruit formation.

Question 2.
What factors do you think contribute to the growth of plants? (Page 138)
Answer:
Factors like water, sunlight and soil nutrients play important roles in plant growth.

Question 3.
How do plants obtain the food they need to grow? (Page 140)
Answer:
Plants obtain their food through the process of photosynthesis, where they use sunlight, water and carbon dioxide to make glucose.

Question 4.
Why is the leaf decolourised at the beginning of the iodine test activity for photosynthesis? Page i4i
Answer:
The leaf is decolourised to remove the green chlorophyll so that any colour change due to the iodine test becomes clearly visible, helping us detect the presence of starch.

Question 5.
How does sunlight contribute in the production of starch in plants? (Page 141)
Answer:
Sunlight provides energy for photosynthesis, allowing plants to convert carbon dioxide and water into glucose.

Question 6.
Besides sunlight and chlorophyll, which other components are necessary for plants to make their food? (Page 143)
Answer:
Carbon dioxide and water are also necessary for plants to prepare food through photosynthesis.

Question 7.
Which gas from the air is essential in the process of food preparation in plants? (Page 143)
Answer:
Carbon dioxide is the essential gas from the air used in the process of food preparation in plants.

Question 8.
Do green parts of a plant other than leaves help in making food? (Page 144)
Answer:
Yes, green parts of plant other than leaves, such as stems and branches, also perform photosynthesis.

Question 9.
Which part of the plant is involved in the synthesis of starch? page 144
Answer:
Leaf is the part of the plant involved in the synthesis of starch.

Question 10.
During the process of photosynthesis, do plants only absorb substances or do they also release Something. (Page 144,145)
Answer:
During photosynthesis, plants release oxygen into the air.

Question 11.
Which part of the plant helps in the exchange of carbon dioxide and oxygen? (Page 146)
Answer:
The stomata on the leaves help in the exchange of carbon dioxide and oxygen.

Question 12.
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 move to all parts of the plant through the xylem tissue.

Question 13.
How does food get transported to other parts of a plant? (Page 148)
Answer:
Food is transported to other parts of the plant through the phloem, which carries the sugars produced in the leaves to the rest of the plant.

Question 14.
Do plants also respire like humans do? (Page 14)
Answer:
Yes, plants also respire like humans, breaking down glucose to release energy.

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

Question 1.
Complete the following table.

Features	Photosynthesis	Respiration
1. Raw materials
2. Products
3. Word equation
4. Importance

Answer:

Feature	Photosynthesis	Respiration
1. Raw materials	Carbon dioxide, water, sunlight	Glucose, oxygen
2. Products	Glucose, oxygen	Carbon dioxide, water, energy (ATP)
3. Word equation	Carbon dioxide + Water → Glucose + Oxygen (in sunlight)	Glucose + Oxygen → Carbon dioxide + Water + Energy
4. Importance	Prepares food for the plant and releases oxygen	Releases energy for plant growth and activities

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 photosynthetic organisms disappeared, there would be no production of oxygen and no natural source of food. This would disrupt the food chain, leading to the extinction of herbivores first, followed by carnivores and eventually all life forms, including humans, due to lack of oxygen and food.

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 food (glucose) prepared in the leaves through photosynthesis. The leaves synthesise food, which is then transported to different parts of the plant, including the potato, through the phloem tissue, where it is stored as 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 because it increases the surface area to capture more sunlight and allows better exposure to air for the exchange of gases like carbon dioxide and oxygen.

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:
In the process of respiration, X stands for glucose, Y stands for oxygen and Z stands for water.

Question 6.
Krishna set-up 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 the given figure

Answer the following questions.
(i) What idea might she be testing through this experiment?
Answer:
Krishna is testing the importance of sunlight in the process of photosynthesis.

(ii) What are the visible differences in plants in both the conditions?
Answer:
The plant kept in sunlight appears healthy and green, while the plant in the dark room may look weak, yellowish and show poor growth.

(iii) According to you, leaves of which plants confirm the iodine test for the presence of starch?
Answer:
The leaves of the plant placed in sunlight will confirm the iodine test by turning blue-black, indicating the presence of starch.

Question 7.
Vani believes that ‘carbon dioxide is essential for photosynthesis’. She puts an experimental set-up, as shown in figure, to collect evidence to support or reject her idea

Answer the following questions
(i) In which plant(s) in the above setup(s) will starch be formed?
(ii) In which plant(s) in the above setup(s) will starch not be formed?
(iii) In which plant(s) in the above setup(s) will oxygen be generated?
(iv) In which plant(s) in the above setup(s) will oxygen not be generated?

Answer:
(i) Starch will be formed in the plant placed in sunlight with carbon dioxide (a), as photosynthesis will occur.

(ii) Starch will not be formed in the plants placed in sunlight without carbon dioxide (b), dark with carbon dioxide (c) and dark without carbon dioxide (d) due to the absence of either sunlight or carbon dioxide as these two required for photosynthesis.

(iii) Oxygen will be generated in the plant placed in sunlight with carbon dioxide (a), as oxygen is a by-product ofphotosynthesis.

(iv) Oxygen will not be generated in the plants placed in sunlight without carbon dioxide (b), dark with carbon dioxide (c) and dark without carbon dioxide (d), as photosynthesis will not occur in these conditions.

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. 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:
Ananya wants to find out how the presence of a snail, a water plant or both affects the levels of carbon dioxide in the water.
She will know if she is correct by observing the colour change in the carbon dioxide indicator after 2-3 hours.
If the water turns yellow, it indicates an increase in carbon dioxide, whereas if it turns blue, it indicates a decrease in carbon dioxide. The test tubes with only snails will show an increase in carbon dioxide due to respiration, while the test tubes with plants (especially with both a snail and plant) might show a decrease in carbon dioxide due to photosynthesis.

Question 9.
Design an experiment to observe if water lltransportation in plants is quicker in warm or cold conditions.
Answer:
Aim To compare the rate of water transport in plants under warm and cold conditions. Materials Required Two fresh celery stalks (with leaves), two clear glasses, water, food colouring.

Procedure

1. Fill each glass three-quarters full with water.
2.  Add 5 drops of the same food colouring to each glass and stir.
3. Trim the cut ends of the two celery stalks and immediately place one stalk in each coloured glass.
4. Put one glass in a warm location and the other in a cold location.
5. After 1 hour, observe and compare how far the dye has travelled up each stalk (noting colour in leaves or along the stalk).

Observation
The celery in the warm spot shows coloured veins higher and more quickly than the celery in the cold spot.

Conclusion:
Warmer conditions increase the rate of water transport {via transpiration) in plants, while colder conditions slow it down.

Question 10
Photosynthesis and respiration are essential to maintain balance in nature. Discuss.
Answer:
Photosynthesis and respiration are vital for maintaining balance in nature. Photosynthesis, carried out by plants, produces oxygen and food (glucose) using carbon dioxide and water. This oxygen is crucial for respiration, a process in which all living organisms breakdown glucose to release energy, producing carbon dioxide as a by-product. The carbon dioxide released in respiration is used by plants in photosynthesis. Thus, the two processes form a cycle that balances oxygen and carbon dioxide levels in the atmosphere, ensuring the survival of plants, animals and other organisms.

Class 7 Life Processes in Plants Question Answer (Activities)

Activity 1 (Page 138)

Aim To investigate the factors required for the growth of plants.
Materials Required Earthen pots filled with garden soil, plant saplings (chilli or tomato), water.

Procedure

1. Take three earthen pots (or used bottles/containers) of the same size and fill them with garden soil.
2. Plant saplings of a fast-growing plant, such as chilli or tomato, in each pot.
3. Label the pots as A, B and C. Count the number of leaves on each sapling and note your observations.
4. Place pot A in direct sunlight. Keep the soil in this pot slightly moist by adding water daily.
5. Place pot B in direct sunlight, but do not add water to the soil.
6. Place pot C in a dark location. Keep the soil in this pot slightly moist by adding water daily.
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 the changes in the observation table.

Observation

Pots kept under different conditions	Availability of		Height of plant (cm)		Number of leaves		Colour of leaves (Green/Yellow)
Pot A : In direct sunlight with water	Sunlight	Water	Day 1	After 2 weeks	Day 1	After 2 weeks	Green
Pot B : In direct sunlight without water	Yes	Yes					Yellow
Pot C: In the dark with water	Yes	No					Yellow

Conclusion:
The plants require both sunlight and water for their growth.

Viva Questions
1. What differences did you observe between the plants in the three pots?
2. Which pot has the plant with the maximum growth?
3. Which pot has the plant with the least growth?
4. Name the factors other than water and sunlight that are essential for the growth of a plant.

Activity 2 (Page 140)

Aim To find out the role of chlorophyll in photosynthesis.
Materials Required Leaf, alcohol, test tube, water, beakers, sprit lamp, diluted iodine solution.

Procedure

1. Take a leaf and keep it boiling water for five minutes, so that it gets soften.
2. Dip the leaf in a test tube, containing alcohol.
3. Place the test tube in a beaker, containing boiling water and wait until the leaf becomes colourless.
4. Take out the leaf and place it on a plate.
5. Now, put a few drops of diluted iodine solution with the help of a dropper on the decolourised leaf.
6. Wait for a few minutes and then observe the colour of leaf.

Observation
The colour of the leaf changes to blue-black.

Conclusion:
This activity indicates the presence of starch as food in the leaf. Precautions Alcohol should never be placed near a heat source directly as it is highly tiammable and can easily lead to fire and burns.

Viva Questions
1. Why does the leaf changes colour to blue-black?
2. Why alcohol should not be placed near a heat source directly?

Activity 3 (Page 142)

Aim To test that sunlight is necessary for the process of photosynthesis.
Materials Required Two potted plants (same kind), alcohol, beakers, test tube, burner, iodine solution, match stick, tracing paper, pen.

Procedure

1. Take two plants of same kind in different pots.
2. Label them as ‘Pot A’ and ‘Pot B’.
3. Keep the ‘Pot A’ in dark and ‘Pot B’ in light for 3 days.
4. After 3 days pick one leaf from both the plants and perform iodine test as given in activity 2.
5. Now, record the observation in the table given below. Observation

Observation

Conclusion:
Only the green patches of the leaf placed in sunlight turned blue-black, showing the presence of starch and confirming that photosynthesis occurred. Green patches from a leaf kept in the dark and non-green patches from the leaf in sunlight did not turn blue-black. This indicates that both chlorophyll and sunlight are necessary for photosynthesis. Non-green patches may lack enough chlorophyll to produce detectable amounts of starch.

Viva Questions
1. Why did the leaf kept in dark not show positive iodine test?
2. What does the blue-black patches on the leaf indicate?

Activity 4 (Page 143)

Aim To test the role of air in photosynthesis.
Materials Required Potted green plant, wide-mouthed bottle, caustic soda, split cork.

Procedure

1. Keep a healthy potted green plant in complete darkness for 2-3 days to destarch it.
2. Take a wide-mouthed bottle and pour some caustic soda (sodium hydroxide) into it.
3. Select one leaf from the destarched plant.
4. Insert the leaf through a split cork so that half of the leaf is inside the bottle and half remains outside.
5. Seal the cork tightly around the leaf stalk to prevent air exchange.
6. Place the entire setup in bright sunlight for few hours.
7. Observe and record the availability of water, sunlight, chlorophyll and carbon dioxide in the table.
8. Remove the leaf and test it for starch using the iodine test, as was done in Activity 2.
9. Record the observations in table below.

Observation

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

Conclusion:
Carbon dioxide present in air is essential for photosynthesis. Precautions Caustic soda is a strong chemical that can cause skin burns; only teachers should handle it.

Viva Questions
1. Why caustic soda is added into the bottle?
2. Mention the chemical name of caustic soda.
3. Write the significance of the experiment.

Activity 5 (Page 145)

Aim To demonstrate that oxygen is released during the process of photosynthesis.
Materials Required Beaker, test tube, water plant, funnel.

Procedure

1. Take two identical beakers and fill them with clean water.
2. Place a small pieces of a water plant at the bottom of each beaker.
3. Invert a funnel over the plant in each beaker.
4. Fill two test tubes with water and carefully invert them over the narrow end of each funnel so that no air enters.
5. Label the two setups as A and B. Place setup A in sunlight and place setup B in a dark area.
6. Leave both setups undisturbed for a few hours.
7. Observe the test tubes in both setups carefully.

Observation Bubbles are seen in setup A kept, but not in setup B.

Conclusion:
Light is necessary for photosynthesis, as oxygen is released only in the presence of light.

Viva Questions
1. What difference is observed in setup A and setup B?
2. Why are bubbles formed in the test tube in setup A?
3. Why should the water plant be fully submerged in water?

Activity 6 (Page 147)

Aim To observe stomata on the lower surface of a leaf using a microscope.
Materials Required A fresh leaf (from rhoeo, money plant, onion, Hibiscus, Coleus or any grass), water, beaker, watch glass, microscope slide, coverslip, dropper, ink, forceps, microscope.

Procedure

1. Collect a fresh leaf from any of the given plants.
2. Put the leaf in a beaker filled with water to keep it fresh.
3. Carefully peel a thin layer from the lower surface of the leaf using forceps.
4. Place the peel in a watch glass containing water. ^
5. Take a microscope slide and put one drop of water on it.
6. Using forceps, transfer the leaf peel from the watch glass to the slide.
7. Add a drop of ink to the peel using a dropper to stain it.
8. Place a coverslip gently over the peel to avoid air bubbles.
9. Observe the slide under the microscope.

Observation
Tiny pores can be seen on the leaf peel. These are the stomata and they are surrounded by guard cells.

Conclusion:
Stomata are present on the surface of leaves.

Viva Questions
1. Why is ink used in this experiment when observing the leaf peel under the microscope?
2. What is the function of stomata on the surface of the leaf?

Activity 7 (Page 148)

Aim To show that water is transported through xylem.
Materials Required Two glass tumblers, water and red ink, twigs of two similar tender herb (e.g. white sadabahar and balsam) and a blade.

Procedure

1. Take two transparent tumblers and label them as A and B.
2. Fill one-third of each tumbler with clean water.
3. Add a few drops of red ink to tumbler B.
4. Take two identical plant stems and cut their bases obliquely underwater.
5. Immediately place one cut stem into tumbler A and the other into tumbler B.
6. Observe these plants the next day.

Observation Red colour appears in the stem, leaves and flower of the plant in tumbler B.
Conclusion:
Water moves up the stem through xylem.

Viva Questions
1. Can you observe the red colour in the stem?
2. How does the red ink travel upwards in the plant?

Activity 8 (Page 149)

Aim To demonstrate that germinating seeds release carbon dioxide during respiration.
Materials Required Moong bean seeds, conical flask, cotton, water, cork with two holes, two glass tubes, two test tubes, lime water, rubber tubing, cork with one hole.

Procedure

1. Soak some moong bean seeds in water overnight.
2. Put a layer of cotton in a conical flask and moisten the cotton with water to keep it wet.
3. Place the soaked seeds over the wet cotton in the conical flask.
4. Cover the mouth of the conical flask with a cork having two holes.
5. Fit two tubes A and B through the two holes on the cork, as shown in Fig.
6. Leave it undisturbed for 24 hours in the dark.
7. Take two test tubes and fill them with lime water.
8. Cover the mouth of one test tube with a cork having one hole in it.
9. Dip one glass tube in the test tube through a hole in the cork.
10. Connect the flask and test tube with a rubber pipe as shown in Fig.

Observation The lime water turn milky in the test tube connected to the flask.
Conclusion:
The lime water turns milky due to the presence of carbon dioxide (C0₂) released by the germinating seeds. This proves that respiration occurs in plants and produces carbon dioxide as a by product.

Viva Questions
1. Why moong bean seeds are soaked in water overnight?
2. What is the role of the cork and rubber tubing in this experiment?
3. Why does the lime water turn milky in the test tube connected to the flask?
4. Where does the carbon dioxide in the flask came from?