Page 92 - Biology - XII

Results
1. The water level in the graduated tube falls after some time.
2. The fi nal weight of the arrangement is diff erent from that of the initial weight.

Observation Table - 1
Transpiration and absorption ratio

S. Initial weight Final weight Diff erence in weights
No. W 1 W 2 = W - W 2
1
1.

2.

Discussion
The diff erence in the weights shows the amount of water transpired by the leaves.

Observation Table - 2
Transpiration and absorption ratio
S. Water level in graduated Water level in graduated Diff erence in levels
No. tube (initial) tube (fi nal) (L – L )
L L 2 1
1 2
1.

2.

Conclusion
The diff erence in the water levels in the graduated side tube indicates the amount of water absorbed
by the plant.

Precautions
1. Take the weights correctly.

2. Note the water level in the side tube correctly.
3. Apply vaseline at cork junction to avoid evaporation through the spaces.

VIVA VOCE

Q1. Why did you take the weight before/after the experiment?
Ans. The diff erence in the weights shows the amount of water transpired by the leaves.
Q2. What is transpiration?
Ans. The loss of water in the form of water vapour from the living aerial parts of plant is called transpiration.

Q3. Can you perform this experiment by any other way/apparatus?
Ans. Yes, by use of a conical fl ask and a leaf.
Q4. Why did you use a plant in this experiment?
Ans. Use of a plant shows rapid result because of number of leaves.

91