Page 108 - Biology - XII

Q2. Food supply increases
(a) the growth of plant (b) height of plant

(c) oxygen supply (d) all of these
Q3. Plant has growth regions called
(a) apical meristems (b) intercalary meristems
(c) lateral meristems (d) all of these

Q4. Intense light
(a) helps plant growth (b) speed plant growth

(c) retards plant growth (d) none of these
Q5. There are
(a) three phases of growth (b) two phases of growth

(c) one phase of growth (d) no phase of growth

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

PROJECT - 7

No. 0 No. 3
Objective
To study smoke density emitted from scooter/motorcycle by
Ringelmann scale.

Principle/Theory
1. The amount of CO, HC, NOx diff ers during idling, All White 60% Black
accelerating, cruising, and decelerating in a motor vehicle. No. 1 No. 4
2. Next to thermal power plants, automobiles are a source
of considerable air pollution. Two-wheelers form more
than 65% of the automobile. 50% of the pollutants in air

in major cities comes from automobile exhausts. In all
major cities of the country about 800–1000 tonnes of
pollutants are emitted into the air daily. 20% Black 80% Black
No. 2 No. 5
Materials Required
White card sheets (postcard size)

Procedure
1. Take white cards of postcard size.
2. Now, hold the white card against a source of smoke 40% Black All Black
when the engine is on. (Say exhaust pipe of the scooter, Fig. 7.1: Ringelmann scale for
car, or any other vehicle.) measuring smoke blackness
3. Compare the blackness of the card with Ringelmann’s scale for measuring smoke blackness.

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