Q11 of 60 Page 1

What is DNA copying? State its importance.

DNA copying or DNA replication refers to copying of parents traits and genes and passing them to the next generation.

Importance of DNA replication-

a) Characteristics of parent organisms are transmitted to its offsprings.

b) Also some variations are produced that increases the rate of survival of species.

c) This also forms the basis of evolution.

How many groups and periods are there in the modern periodic table? How do the atomic size and metallic character of elements vary as we move :

(i) down a group and (ii) from left to right in a period?

From the following elements: ₄Be; ₉F; ₁₉K; ₂₀Ca

(i) Select the element having one electron in the outermost shell.

(ii) Two elements of the same group.

Write the formula of and mention the nature of the compound formed by the union of ₁₉K and element X (2,8,7).

Explain budding in Hydra with the help of labeled diagrams only.

List any four contraception’s used by humans. How does their use have a direct.