(a) What is a gonad?
(b) Why is it called primary sex organ?
(c) Provide its secondary function.

(a) A gonad is an organ which produces gametes for sexual reproduction.
(b) It is called primary sex organ because its main function is the production of gametes that take part in sexual reproduction.
(c) The secondary function of gonad is to produce sex hormones which are responsible for the development of secondary sexual characters and proper functioning of sex organs.