Q. Sino – atrial node is called as the pacemaker of our heart. Why?

Q. Which division among plants has the simplest organisms?

Q. What is meant by de – urbanization?

Q. Write 10 lines on the usefulness of microorganisms in our lives.

Q. Answer the following questions briefly.Why is the Northern Hemisphere called the ‘Land Hemisphere’?

Q. Define geitonogamy and xenogamy. Give advantages of self – pollination and cross – pollination. Explain how dichogamy favors cross pollination?

Q. What is the essential condition for diffraction of light to occur?

Q. What is the taste of baking soda?

Q. Give a brief life sketch of Laxmi Lakra.

Q. Name the two broad divisions of the peninsular plateau.