What is clock? Write the principle and its types.

Write a note on nephridia and its types.

What is transformer ? Write its principle and write its construction.

What is food chain? Describe two principles types of food chains.

Write a note on extinction and its types.

What is a lever ? State its principle.

(a) What is an electric motor ? Write the principle on which its working is based . (b) What is short circuit ? Give its possible cause.

What does PCR stand for? Write its principle and name the different steps involved in PCR.

What does PCR stand for? Write its principle and name the different steps involved in PCR.