Page 93 - Biology - XII

Q5. How can you measure the absorption of water in this experiment?
Ans. By diff erence in the water levels in the side tube.

COMPETENCY BASED QUESTIONS

Multiple Choice Questions

Q1. A rise in CO concentration in atmosphere from 0.03% to 0.05%
2
(a) opens the stomata (b) increases the transpiration
(c) speeds up photorespiration (d) none of these

Q2. Cuticular transpiration is about
(a) negligible (b) cent percent
(c) 40% of the total transpiration (d) 20% of the total transpiration

Q3. Lenticular transpiration forms about
(a) 0.1% of total water loss (b) 10% of total water loss

(c) 20% of total water loss (d) 0.002% of total water loss
Q4. Less than 1% of the energy received from sun is used in the process of photosynthesis. Which
process of plant helps in dissipating excess of sun’s energy?
(a) Respiration (b) Transpiration
(c) Guttation (d) None of these

Q5. There are ________ kinds of transpiration according to the structures through which it occurs.

(a) 5 (b) 4 (c) 3 (d) 2
Answer key
1. (d), 2. (d), 3. (a), 4. (b), 5. (c)

PROJECT - 2

Objective
To fi nd out/study the elements present in ash.

Principle/Theory
1. In 1840, Liebig laid the concept of elements as plant nutrients. He put forward his revolutionary
theory of mineral nutrition.
2. Plants consist of large proportion of water. The percentage may vary from 40% to 50% in wood parts
to 70–80% in herbs and 85–95% in succulent plants (juicy) and fruits. Algae have about 75–98% of
water. In dry substances, in plants the percentage vary from 20% to 60%.

3. We can distinguish between dry substance of the plant and water by drying it. The dry substance can
be distinguished (by burning) between the combustible or organic material and the incombustible
inorganic substance or ash.

4. Thus, ash is incombustible inorganic substance. This is confi rmed after burning of wood, other plant
tissues, leaves, or cigar, cigarette, bidi, etc.

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