Due to a gradual weakening of ciliary muscles and diminishing flexibility of the eye lens a certain defect of vision arises. Write the name of this defect. Name the type of lens required by such persons to improve the vision. Explain the structure and function of such a lens.

You have been selected to talk on “ozone layer and its protection” in the school assembly on ‘Environment Day.’
(a) Why should ozone layer be protected to save the environment?
(b) List any two ways that you would stress in your talk to bring in awareness amongst your fellow friends that would also help in the protection of ozone layer as well as the environment.

33.

Name the organ that produces sperms as well as secretes a hormone in human males. Name the hormone it secretes and writes its functions.

Name the parts of the human female reproductive system where fertilisation occurs.

Explain how the developing embryo gets nourishment inside the mother's body.

How do Mendel’s experiments show that
Traits may be dominant or recessive?

How do Mendel’s experiments show that
Inheritance of two traits is independent of each other?

A concave mirror produces three times magnified image on a screen. If the object is placed 20 cm in front of the mirror, how far is the screen from the object?

Draw a ray diagram to explain the term angle of deviation.

Why do the component colours of incident white light split into a spectrum while passing through a glass prism, explain?