Page 15 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

is 10°C - 35°C. Extremely high temperature destroys the enzymes which in turn

decreases the rate of photosynthesis.
(d) Water: The rate of photosynthesis decreases underwater deficient conditions. It

is because water is not only a raw material for photosynthesis but also controls
opening and closing of stomata.

8. Write an experiment to show that oxygen is released during photosynthesis.
Ans. We can demonstrate with the help of the following experiment that oxygen is released

during photosynthesis:
Aim: To demonstrate that oxygen is released during photosynthesis

Principle: Plants start photosynthesising in the presence of sunlight and release
oxygen.

Material required: Freshly cut aquatic plant, such as hydrilla, beaker, test tube,
funnel, matchstick and water

Procedure:
• Take some freshly cut hydrilla twigs

in a beaker and cover them with an
inverted funnel.

• Fill the beaker with water, such that
the stem of the funnel is below the

water level.
• Fill a test tube with water and invert

it ov er the stem of the funnel.
• Keep the set-up under the sunlight

for a few hours.
• Collect the air bubbles in the inverted

test tube. These bubbles push down
the water (being lighter than water).

• Take out the test tube carefully without letting the gas escape out from it.
• Bring a burning matchstick near the mouth of the test tube and observe.

Observations: The burning matchstick burns brighter when brought close to the
mouth of the test tube indicating that the gas released during photosynthesis is

oxygen.

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