Which of the following helps in the repair of tissue and fills up the space inside the organ?

Flexibility in plants is due to

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 ............. .

Name the muscular tissue which is present in the iris of the eye. What is the shape of these cells?

Write six functions of the epithelial tissue.

$A$ neuron consists of