Page 14 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

5. What is fungus? Does fungus only result in a disease or can it help too?

Ans. Fungus (plural:fungi) is a wide variety of organism that reproduce by spores, including
the mushrooms, moulds, yeasts, etc. They start growing when suitable conditions

are provided to them, such as moisture, damp and dark places. In such conditions
spores of most fungi grow a network of slender tubes called hyphae that spread into

and feed off of dead organic matter or living organisms using digestive juices. These

juices convert the decaying matter into a solution. The nutrients from this solution
are then absorbed by the fungi.

Most of the fungi spoil food, fruits, vegetables, etc. during rainy season. They can
also cause diseases in humans, animals and plants.

However, they play an important role in ecosystem. They help in breaking down
complex dead and decaying organic matter into simpler forms that can easily be

used by the plants again. Also, some mushrooms are edible and can be consumed by

humans.
So fungus is harmful as well as helpful too.

6. Write a brief note on how a pitcher plant traps and digests insects.
Ans. Insectivorous plants like pitcher plant derive nutrients by trapping and digesting

insects and small animals.
The leaves of pitcher plant are modified into pitcher-like structures. The apex of

the leak forms the lid of the pitcher. The glands in the pitcher produce a sweet and

sticky nectar along the edges and underside of the hood to attract insects. Insect is
attracted towards the bright colour of the edge of the pitcher.

Once an insect crawls into the pitcher, it falls into a pool of digestive juices. These
juices slowly break down the insect into a liquid mixture, which gets absorbed into

the leaf.
7. Write in detail about the factors that affect the rate of photosynthesis.

Ans. The factors that affect the rate of photosynthesis are as follows:

(a) Intensity of sunlight: The rate of photosynthesis increases with the increase in
the intensity of light.

Sunlight is made up of seven colours. But rate of photosynthesis is maximum in
blue and red light whereas it is minimum in green light.

(b) Concentration of carbon dioxide: The rate of photosynthesis increases with the
increase in the concentration of carbon dioxide, provided there is enough light.

(c) Temperature: The effect of temperature on the rate of photosynthesis varies with
the habitat of a plant. The optimum range of temperature for photosynthesis

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