Which of the following does not lose their nucleus at maturity?

Fill in the blanks:
$(a)$ Cork cells possess ........... on their walls that make them impervious to gases and water.
$(b)$ .................. have tubular cells with perforated walls and are living in nature.
$(c)$ Bone possesses a hard matrix composed of ............... and ............. .

Survival of plants in terrestrial environment has been made possible by the presence of

Animal tissues are different from plant tissues. State the reasons.

$A$ nail is inserted in the trunk of a tree at a height of $1$ metre from the ground level. After $3$ years,the nail will:

Differentiate the following activities on the basis of voluntary $(V)$ or involuntary $(IV)$ muscles:
$(a)$ Jumping of a frog
$(b)$ Pumping of the heart
$(c)$ Writing with hand
$(d)$ Movement of food in your intestine