NCERT Class 7 Science Model Paper 2 Questions and Answers Part 5

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35. Explain the following terms.

(i) Afforestation

(ii) Food web

(iii) Canopy

(iv) Food chain

(v) Chipko movement

Ans: (i) Afforestation: Large-scale planting of trees in deforested areas or for commercial purpose is called Afforestation.

(ii) Food Chain: Simple representation of energy flow in nature is called food chain.

(iii)Such a cover or roof formed by the tree branches in the upper regions is called a canopy

(iv) Food web: Interconnected food chains depicting the complex representation of energy flow in nature is called food web.

(v) Chipko movement: In the 1970s, an organized resistance to the destruction of forests spread throughout India and came to be known as the Chipko movement. The name of the movement comes from the word ‘embrace’, as the villagers hugged the trees, and prevented the contractors from falling them.

36.

(i) Draw a well labelled diagram of flower.

(ii) What happens to the flower after fertilization?

OR

(i) Draw a well labelled diagram showing process of fertilization in flowering plants?

(ii) How are plants benefitted by seed dispersal?

(iii) How does seed dispersal takes place in

(a) Castor

(b) Madar

Ans: (i)

The Flower Loses its Bright Colour

The Flower Loses Its Bright Colour

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(ii) If you observe carefully, you may see following changes in a flower :

1. The flower loses its bright colour.

2. The sepals, petals and stamens fall off.

3. The ovary increases in size and becomes the fruit. The fruit thus is the ripened ovary.

4. The ovary wall becomes the fruit wall.

5. Inside the ovary, the ovules develop to form the seeds.

The seeds develop from the ovules. The seed contains an embryo enclosed in a protective seed coat. Some fruits are fleshy and juicy such as mango, apple and orange. Some fruits are hard like almonds and walnuts.

OR

(i)

Seed dispersal help the plants

Seed Dispersal Help the Plants

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(ii) Seed dispersal help the plants to

(a) Prevent overcrowding.

(b) Avoid competition for water, minerals and sunlight, and

(c) Spread to new habitats.

(iii) (a) Castor -Sudden jerks

(b) Madar -Wind