Question

conclusion of comparative study of rates of transpirtation in the upper and lower surface of leaf, using four leaf experiment​

Answer 1

Answer:

What is Transpiration?

It is the process of water movement through a plant which evaporates through the aerial parts of the plant into the atmosphere. It occurs through specialized openings known as stomata that are present on leaves which are chiefly concerned with a gas exchange during the process of respiration and Photosynthesis. The stomata are girdled with specialized cells that govern the closing and the opening of the stomata known as guard cells. They assist in the regulation of the rate of transpiration.

Material Required

A potted plant

Forceps

Filter paper strips

Wire gauze

3% cobalt chloride solution

Petri Dish

Binder clips

Glass Slide

Procedure

Into the Petri dish, pour the cobalt chloride solution

Dip a few strips of filter paper into the solution

Allow the strips to stay in the solution for a few minutes, watch them turn pink in colour

With the help of forceps, separate the strips

Allow the strips to dry by placing them on the wire gauze

Upon drying, the strips turn blue in colour

Pluck a healthy leaf from the potted plant, clean it to remove excess droplets with the help of filter paper

After drying on the wire gauze, set the dried strips one on the upper surface of the leaf and one on the lower surface.

Now place 2 glass slides on each surface of the leaf, i.e., the upper surface and lower surface.

With the help of binder clips, secure the slides.

Observe and make note of the time that is consumed by the paper to switch its colour from blue to pink.

Observation

Through the experiment carried out, it is observed that the amount of time taken for the colour change of the cobalt chloride paper from blue to pink on the lower surface of the leaf is lesser than the upper leaf surface.

Conclusion

The rapid switch of the colour of the cobalt chloride paper on the lower surfaces depicts that rate of loss of water vapour is higher on the lower surface than the upper surface.

Precautions

The plant that is used in the experiment should always be a healthy and well-watered plant

The paper should always be handled with forceps or well-dried hands

The leaf should completely be wiped off excess water before placing the strips

Viva Questions

Q.1. List the importance of the process of transpiration. Any two points.

A.1. Following is the significance of the process of transpiration:

It helps the plant to absorb water from the soil, which is transported from roots to leaves and impacts the transpiration pull.

During the process of evaporation, it cools down the surface of plants.

Explanation:

Answer 2

A comparative study of the rates of transpiration in the upper and lower surface of leaves using four-leaf experiments indicates that the rates of transpiration are higher on the lower surface of leaves than on the upper surface.

• The rates of water loss in the two wet-bulb experiments are higher on the lower surface of the leaves than on the upper surface, indicating that more water is evaporating from the lower surface.
• The rates of water uptake in the two dry-bulb experiments are also higher on the lower surface of the leaves than on the upper surface, indicating that more water is being taken up by the leaves from the lower surface.
• These observations suggest that the stomata, which are responsible for regulating transpiration, are more numerous and more open on the lower surface of leaves than on the upper surface.
• This is likely due to the fact that the lower surface of leaves is generally more shaded and cooler than the upper surface, which helps to reduce water loss and maintain the plant's water balance.
• Overall, this comparative study provides insight into the factors that influence transpiration rates in plants and highlights the importance of stomatal regulation in maintaining water balance.

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