A particular type of high energy invisible electromagnetic wave help us to study the structure of crystals. Name these rays and give another important use of these rays.

Name any two, electromagnetic waves, which have a frequency higher than that of violet light. State one use of each.

Name the electromagnetic waves used for studying crystal structure of solids. What is its frequency range?

Name a domestic device in which an electro magnet is used.

Name two electromagnetic waves of wavelength smaller than that of violet light. State one use of each.

Name two gases which can be used in the study of the fountain experiment. State the common property demonstrated by the fountain experiment.

State the name and the range of wavelength of the invisible electromagnetic waves beyond the red end of the visible spectrum

Study the diagram given below and answer the questions that follow: Name the structure shown in the diagram. State in which part of the body it is present.

The diagram shown below is the longitudinal section of a testis of man. Study it carefully and answer the questions that follow : (i) Label the parts numbered 1 to 3 in the diagram. (ii) In which part of the testis are the sperms ? (iii) State the functions of the parts labelled 1 and 3 in the diagram. (iv) Name the cells that secrete Testosterone. (v) Draw a neat, labelled diagram of a sperm.

(a) Name the two growth models that represent population growth and draw the respective growth curves they represent. (b) State the basis for the difference in the shape of these curves. (c) Which one of the curves represent the human population growth at present? Do you think such a curve is sustainable ? Give reason in support of your answer.