Frank ICSE Class 10 Biology Solutions Chapter 6 Transpiration

Question 1. Answer the following (only in few words):
(i) What is transpiration?
(ii) In which form, water comes out in transpiration?
(iii) Where does transpiration take place in leaves? Give names of the various parts.
(iv) Give one important difference between transpiration and evaporation.
(v) When does stomatal transpiration take place in plants?
(vi) From which structure cuticular transpiration occur in plants?
(vii) How does transpiration take place in night?
(viii) What is the effect of temperature on transpiration?
(ix) What is the impact of more atmospheric pressure on transpiration?
(x) What is the relationship between transpiration water and water absorbed from the soil?
Solution 1:
1. Transpiration: it is the loss of water from the plant’s aerial portions in the form of water vapour.
2. In water vapour form.
3. In leaves transpiration take place by stomata. Stomata consist of guard cells, epidermal cells, chloroplast and nucleus.
4. The major difference between the transpiration and evaporation is during transpiration in the water can loss by only aerial part of the plant but during evaporation the water can loss by the any surface of the plant.
5. Stomata transpiration occurs primarily during the day, when the stoma’s guard cells are fully turgid and the stomata are fully open.
6. Cuticular transpiration occurs when the cuticle on the epidermis of leaves and herbaceous stems is broken.
7. Because photosynthesis does not occur at night and the stomata remain closed, the rate of transpiration slows.
8. There is a direct relationship between temperature and transpiration: when the temperature rises, the rate of transpiration rises as well.
9. As air pressure rises, less water vapour escapes and the rate of transpiration decreases
10. The relationship between transpiration water and water absorbed from the soil is that if the soil is deficient in water, the rate of water absorption decreases, lowering the rate of transpiration, and conversely, if the soil is excessively wet, the rate of water absorption increases, raising the rate of transpiration.

Question 2. Suggest with an experiment, evaporation of water in vapour form, in transpiration process.
Solution 2:
Experiment to show that during transpiration, evaporation of water takes place in vapour form:
1. Take a well-watered potted plant.
2. Cover the potted plant in a polythene sheet.
3. Keep the potted plant in the sunlight.
4. Droplets of water are seen on the inner side of the polythene. This shows that the water evaporates and condenses to form droplets of water.

Question 3. Write the three major types of transpiration?
Solution 3:
Below are the three major types of transpiration:-
1. Cuticular transpiration
2. Lenticular transpiration
3. Stomatal transpiration

Question 4. When does transpiration occur the highest?
Solution 4:
The rate of transpiration increases with the increase in light intensity, hence the rate of transpiration is maximum during the day.

Question 5. What is the difference between transpiration and evaporation?
Solution 5:
Below are the difference between transpiration and evaporation are:-

Question 6. What is the difference between transpiration and guttation?
Solution 6:
Below are the difference between transpiration and guttation are:-

Question 7. How plants lose water?
Solution 7:
Plants lose water by three mechanisms:
1. Respiration
2. Guttation
3. Bleeding

Question 8. Explain in brief the opening and closing mechanism of stomata.
Solution 8:
Stomata function as turgor operated valves. When osmotic concentration of guard cell increases, water comes in and guard cells become turgid and stomata get open. Whenever stomata osmotic concentration of guard  cells decrease water moves out guard cells become flaccid and hence stomata get closed this increase and decrease in osmotic concentration is explained by a number of theories but not accepted one is described below active k± transport or potassium pump theory to Japanese scientist S Imamura and M. Fujino showed the accumulation of potassium ions in the guard cells during stomata opening later Levitt explain in the influence of the potassium ions in the guard cells and their critical role in stomata movement.

Question 9. Explain the mechanism of stomata?
Solution 9:
Stomata are microscopic pores on the leaves that contain two kidney-shaped guard cells that regulate the flow of air. Stomata open and close in response to variations in the turgidity of their guard cells. The guard cells become turgid as a result of water absorption. Their outside walls pull their inner walls apart. Stomata open as the distance between the guard cells widens. When guard cells become flaccid as a result of water loss, their outer walls do not expand and their inner walls do not pull apart, closing the distance between guard cells and stomata.

Question 10. Why is transpiration important for plants?
Solution 10:
Transpiration is beneficial to plants because it helps them cool down by evaporating excess water. This process also aids in the ascent of sap and the transportation of water and minerals to other plant portions.

Question 11. What do you mean by transpiration? Explain its importance in plants.
Solution 11:
Transpiration is the loss of water from the plant’s aerial portions in the form of water vapour.
1. Create transpiration pull for absorption and transport in plants.
2. Supplies water needed for photosynthesis
3. Transport minerals along with water from the soil to various parts of the plants
4. Also help in maintaining the shape and structure of the plant by keeping their cells in turgid condition.

Question 12. Explain typical structure of stomata.
Solution 12:
The typical structure of stomata:
Stomata are the tiny apparatus found on the epidermis of the leaves and young green steps stems. Each stoma is surrounded by two specialized epidermal cells called guard cells. They differ from epidermal cells in their shape and in the presence of chloroplast. The inner wall of the guard cell is thicker and elastic whereas the outer wall is thin. The intermediate cause of the opening and closing of the stomata is a change in the turgidity of the guard cell. When does it increase within the two guard cells flanking each stomata apparatus or pore the thin outer wall bulge out and force the inner wall into the crescent shape. Opening of the stroma is also aided due to orientation of the micro fibrils in the cell wall of the guard cells. Cellulose micro-fibres are oriented radially rather than longitudinal making it easier for the stoma to open guard cells are broadened by one or more modified epidermal cells called subsidiary cell or accessories cell. Usually the lower surface of the dorsiventral leaf has a greater number of stomata while is isobilateral leaves they are about equal on both surface.

Question 13. Explain the importance of transpiration.
Solution 13:
Importance of transpiration is:
1. Create transpiration pull for absorption and transport in plants.
2. Supplies water needed for photosynthesis.
3. Transport minerals along with water from the soil to various parts of the plants.
4. Also help in maintaining the shape and structure of the plant by keeping their cells in turgid condition.

Question 14. Write short notes on the following:
(i) Hydathodes
(ii) Guttation
Solution 14:
(i) Hydathodes: Hydathodes are unique tissues found near the leaf’s tip and edges. It conducts a crucial function called guttation, which involves the loss of water in the form of droplets. These hydathodes allow water to be ejected from a healthy plant.

(ii) Guttation: Through hydathodes, water is lost in the form of droplets. It usually happens at night when the rate of absorption is high and the rate of transpiration has ceased. The water is forced upwards in the form of drops as a result of the greatest pressure on the roots.

Question 15. Explain how the rate of transpiration is affected on:
(i) a windy day (ii) a foggy day?
Solution 15:
1. A windy day:- if wind is not blowing, water vapour accumulate above the transpiring leaves which decrease the rate of transpiration. The blowing wind removes the accumulated humidity and brings fresh air capable of absorbing water and thus, the rate of transpiration is enhanced. Breeze is wind with velocity 6-50km/hour.
2. A foggy day:- In humid atmosphere ,the rate of transpiration decrease. In dry atmosphere, the relative humidity is low, so the rates of transpiration increase.

Question 16. What is the impact of transpiration on absorption? Explain.
Solution 16:
Transpiration causes the concentration of sap to rise, which enhances the rate of water absorption. In this state, cells take water from their neighbours, such as leaves, stems, and roots, resulting in transpirational pull, which aids in water absorption.

Question 17. The diagram given alongside is an apparatus used to study a particular phenomenon in plants.
(i) Name the apparatus.
(ii) What is it used for?
(iii) What is the role played by the air bubble in this experiment?
(iv) Of what use is the reservoir?

Solution 17:
1. The apparatus Potometer.
2. A potometer is a device that measures the rate at which water evaporates.
3. The rate of transpiration will be determined by the pace of movement of the air bubble.
4. Water is supplied to the potometer from the reservoir.

Question 18. What happens to the movement of the air-bubble if the apparatus shown above is kept
(i) in dark.
(ii) in sunlight.
(iii) in front of a fan?
Give a reason in each case.
Solution 18:
(i) The air bubble’s movement will be reduced or slowed.
When the stomata are closed throughout the night, the rate of transpiration is reduced, which reduces the movement of air bubbles.
(ii) The air bubble will move more quickly.
Stomata remain open in the presence of sunshine, the rate of transpiration rises, increasing the circulation of air bubbles.
(iii) The air bubble will move more quickly.
The reason for this is that moving air produces dry air, which increases the rate of transpiration and so the movement of air bubbles.

Question 19. Comment on the following statement:
A well-watered potted plant shows wilting of leaves on a hot sunny day.
Solution 19:
On a hot sunny day, a well-watered potted plant reveals withering leaves. Because the rate of transpiration is greater than the rate of water absorption on hot sunny days,

Question 20. Name the tissue which conducts water absorbed by the roots to the upper parts of a herbaceous plant.
Solution 20:
The tissue which conducts water absorbed by the roots to the upper parts of a herbaceous plant is Xylem tissue.

Question 21. Distinguish between the following pairs of words:
(i) Transpiration and evaporation
(ii) Guttation and bleeding
(iii) Cuticular transpiration and lenticular transpiration
(iv) Stomata and lenticels
Solution 21:
(i) Transpiration and evaporation

Question 22. Name the organ in which guard cells are located and mention their main functions.
Solution 22:
Stomata, Gas exchange and transpiration are two of their primary roles.

Question 23. Name the process by which the aerial parts of a green plant give out water as water vapour.
Solution 23:
The process by which the aerial parts of a green plant give out water as water vapour is Transpiration

Question 24. What is photometer? What is its use?
Solution 24:
A potometer is a device that uses the rate of air bubbles to determine the rate of transpiration. It’s used to figure out how fast you’re sweating.

Question 25. Give any three factors that enhance the rate of transpiration.
Solution 25:
The factors affecting the rate of transpiration are
1. Temperature
2. Light
3. Wind

Question 26. Why do plants absorb more water than what is required by them? Give three uses of this phenomenon.
Solution 26:
1. Plants take in more water than they need. Only 5% of the water used in metabolic reactions is utilised in metabolic reactions, while the remaining 95% is released into the atmosphere as transpiration.
2. This phenomenon serves three purposes:
(i) It aids in the transportation of water and minerals to various parts of the plant;
(ii) It aids in the transportation of water and minerals to various areas of the plant;
(iii) It aids in the transportation of water
3. (ii) It gives the plants a cooling effect.
4. (iii) Excess water is evaporated.

Question 27. (i) Litmus paper is used to demonstrate transpiration from the leaves of the green plant. (True/ False)
(ii) Write the correct substitutes for only the first two words if it is a wrong statement.
Solution 27:
1. False
2. The correct substitutes for the first two words is Cobalt chloride (CoCl₂) paper.

Question 28. Describe an experiment to prove that transpiration occurs more from the lower surface of a leaf.
Solution 28:
An experiment to show that a leaf’s bottom surface is where it transpires the most:
1. Begin with a potted plant.
2. Using two glass slides, place two cobalt sheets chloride papers on opposite side of a leaf of the potted plant.
3. Place the plant in direct sunshine.
4. After some time, the bottom side of the leaf’s cobalt chloride paper became pinkish, whilst the top side remained blue. This demonstrates that the bottom surface of a leaf has a higher rate of transpiration.

Question 29. Name the instrument used for measuring the rate of transpiration.
Solution 29:
Potometer is the instrument used for measuring the rate of transpiration.

Question 30. Name the paper which is used to show loss of water through stomata of a leaf.
Solution 30:
The paper which is used to show loss of water through stomata of a leaf Cobalt chloride paper

Question 31. Low humidity in the atmosphere results in decrease in the rate of transpiration. (True / false)
Solution 31:
False

Question 32. Complete the following statement by choosing the correct alternative given in the brackets:
Loss of water as droplets through leaves of an intact plant is termed ______. (Bleeding/ Guttation/ Transpiration)
Solution 32:
The loss of water in a form of droplets from the leaf margin and tip is known as guttation.

Question 33. Mention three adaptations found in plants to reduce transpiration.
Solution 33:
To reduce transpiration the definition found in a plants are
1. Sunken stomata
2. Modification of leaves into spines
3. Presence of thick cuticle

Question 34. The figure below represents the set-up at the start of certain experiment to demonstrate an activity of plants:
(i) What is the aim of the experiment?
(ii) Why has oil been put in each test tube?
(iii) What will be the observations in the two test-tubes after about 2-3 days?
(iv) Give reasons to explain any change observed as answered in (iii) above.
(v) Why has the test-tube b without the plant, been taken in the experiment?

Solution 34:
1. The experiment’s goal is to demonstrate transpiration.
2. (ii) To prevent water from evaporating from the surface.
3. (iii) The water level in test tube (a) will drop.
4. (iv) Transpiration through the plant’s aerial parts causes the water level in the test tube (a) to drop.
5. (v) As a control experiment, test tube (b) was used. Because there is no transpiration without the plant.

Question 35. Mark the most appropriate answer in the following:
(i) If the rate of transpiration becomes more than the rate of photosynthesis, plant will
(a) Continue to live, but will not be able to store food.
(b) Be killed instantly.
(c) Grow more vigorously because more energy will be available.
(d) Stop growing and gradually die of starvation.
(ii) Transpiration pull will be maximum under which of the following conditions?
(a) Open stomata, dry atmosphere and moist soil.
(b) Open stomata, high humid atmosphere and well irrigated soil.
(c) Open stomata, high humid atmosphere and dry soil.
(d) Closed stomata, dry atmosphere and dry soil.
Solution 35:
1. (d) stop growing and gradually die of starvation.
2. (a) open stomata, dry atmosphere and moist soil.

Question 36. The apparatus shown here is Ganong’s photometer designed to demonstrate unequal transpiration from the two surfaces of a dorsiventral leaf. Before keeping the leaf in between the cups, anhydrous calcium chloride (CaCl2) contained in two small vials were weighted and placed in both the cups. The ends of the cups were weighted and with corks through which two mercury manometers were connected. After a few hours, CaCl2 vials were taken out and weighed again.
(i) What is the purpose of keeping CaCl2 vials inside the cup?
(ii) After a few hours, CaCl2 vials were taken out and weighed again. will you except any difference in weight? If so, give reasons.
(iii) What was expect the purpose of using a manometer?
(iv) What do you mean by transpiration?

Solution 36:
1. Absorb the moisture that has been produced by transpiration.
2. Yes, the weight of CaCl2 vials kept on the lower side will be higher due to increased transpiration and moisture absorption on the lower surface.
3. To check the pressure on the outside and interior.
4. Transpiration is the loss of water in the form of water vapour from the plant’s aerial portions.

Question 37. The diagram alongside represents a structure found in a leaf. Study the same and answer the questions that follow:
(i) Name the parts labeled A and B.
(ii) What is the biological term for the above structure?
(iii) What is the function of the part labeled A?
(iv) Mention two structural features of A, which help in the function mentioned in (iii) above?
(v) Where is this structure likely to be found in a leaf?
(vi) The structure (fig.5.22) helps in the process of transpiration. Explain the term transpiration.
(vii) How many other cells are found surrounding this structure as seen in the diagram?

Solution 37:
(i) A = Guard cell
B = Stomatal aperture
(ii) Stomata
(iii) The guard cells’ job is to assist regulate the rate of transpiration by opening and closing the stomata, so limiting excessive water loss.
(vi) Guard cells have two structural characteristics:
1. The outer wall of the guard cells is thin, while the inside wall is thick.
2. The cytoplasm of guard cells contains chloroplast.
(v) These can be seen on the dorsiventral leaf’s lower surface.
(vi) Transpiration is the loss of water from the plant’s aerial portions in the form of water vapour.
(vii) Number five

Choose the correct answer:

(i) Which one is responsible for guttation?
(a) Diffusion
(b) Root pressure
(c) Transpiration
(d) Photosynthesis

(ii) Rate of transpiration is more, when
(a) High humidity is present in atmosphere.
(b) Air may be stopped.
(c) Extra water is in sky.
(d) Environmental conditions may dry.

(iii) Stomata open during day time because guard cells:
(a) Do photosynthesis and synthesis osmotically active
(b) Are of thin walls.
(c) Are of bean shape.
(d) Help in exchange of gases.

(iv) The cause of wilting is more
(a) respiration
(b) photosynthesis
(c) absorption
(d) transpiration

(v) Guttation is a mechanism of removal of water from plant by
(a) Stomata
(b) hydathodes
(c) lenticles
(d) wounds

(vi) Secretion of sap from apex of non-injured leaf is called
(a) Evaporation
(b) guttation
(c) evapo-transpiration
(d) transpiration

(vii) Transpiration is more
(a) From the upper surface of leaf.
(b) From the lower surface of leaf.
(c) From stem.
(d) From upper and lower surface of leaf.

(viii) The rate of transpiration is determined with the following instrument
(a) Potometer
(b) Evaporimeter
(c) Atmometer
(d) Perimeter

(ix) In herbaceous plants, following percentage of absorbed water comes out
(a) 80
(b) 60
(c) 90
(d) 40

(x) Transpiration rate is high, when
(a) Atmospheric water is saturated with vapour
(b) Light is very dim.
(c) Temperature is low.
(d) Atmosphere is dry and temperature is high.

(xi) More water loss in plants is the cause of wilting. This can be checked by
(a) Keeping plant in bright light
(b) Spraying alcohol on the plant
(c) Layering the bottom with Vaseline
(d) Giving more fertilizer to the soil

(xii) The percentage of cuticular transpiration in plants is:
(a) Approximately 10%
(b) Approximately 20%
(c) Approximately 25%
(d) Approximately 30%

(xiii) Transpiration generates:
(a) Suction force
(b) capillary force
(c) Imbibitions force
(d) atmospheric pressure

(xiv) Transpiration rate is low
(a) due to less surface area of leaf
(b) benting of leaf
(c) By sunken stomata
(d) all of these

(xv) Stomata can open in night also in
(a) xerophyte
(b) gametophyte
(c) hydrophyte
(d) none of these

(xvi) Who had said that “transpiration is a necessary evil”?
(a) Curtis
(b) Steward
(c) Anderson
(d) J.C. Bose