NCERT Science Major Test Model Paper Class 7 2020 Questions and Answers Part 5 (For CBSE, ICSE, IAS, NET, NRA 2022)

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32. (i) Name the largest gland in human body. What does it secrete?

(ii) What is the function of pancreatic juice?

(iii) What is the function and location of villi?

Ans:

(i) Liver is the largest gland in human body. It secretes bile juice.

(ii) Pancreatic juice acts on carbohydrates, proteins, fats and changes them into simpler forms.

(iii) Villi are tiny finger-like projections originating from the walls of the small intestine. They increase the surface area for absorption of the digested food. The blood vessels present inside the villi can absorb the nutrients from the digested food.

33. How is dispersal of seeds beneficial to plants?

Ans:

  • Through seed dispersal, plants are prevented from competition between the plant and its own seedlings for sunlight, water and minerals.
  • It also enables the plants to invade new habitats for wider distribution.

34. How are plants dependent on animals?

Ans:

Dependence of plants on animals

  • For Carbon dioxide: Plants need carbon dioxide to prepare food through photosynthesis. This carbon dioxide comes from animals during respiration.
  • For Pollination: In some plants, pollination is brought about by insects, birds and bats. Without pollination, formation of seeds in these plants would not be possible.
  • For Seed dispersal: Seed dispersal in many plants is through animals and even man. Fruits are eaten by animals such as the birds that carry them to distant places. Finally, the seeds are passed out in their excreta without any damage.

35. (i) Explain what happens to flower after fertilization.

(ii) Draw a well labelled diagram of the process of fertilization in plants.

OR

(i) Explain the process of budding in yeast with the help of a diagram.

(ii) Give any two advantages of vegetative reproduction.

Process of Fertilisation

(ii) Changes in a flower are as follows:

  • The flower loses its bright colour.
  • The sepals, petals and stamens fall off.
  • The ovary increases in size and becomes the fruit. The fruit thus is the ripened ovary.
  • The ovary wall becomes the fruit wall.
  • Inside the ovary, the ovules develop to form the seeds.

OR

  • Budding: Asexual mode of reproduction in which a small outgrowth (bud) appears on the body of the organism. Budding is commonly observed in yeast. A bulb-like projection, called the bud, is formed on the body.
  • The nucleus of the body divides into two. Then, one of the two nuclei passes into the bud. The bud detaches itself from the parent body.
  • It grows to full size and becomes a new individual.
Reproductionn in Yeast by Budding

(ii) Advantages of vegetative reproduction (any 2)

  • It is an easier, rapid and less expensive method of propagation. Plants can be grown in much less time.
  • Seedless plants can be raised.
  • Plants produced by this method are identical copies of the parent plant and show no variations.
  • Plants like banana, sugarcane, sweet potato, rose and jasmine do not produce viable seeds.

Such plants can be easily grown by this method.

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