Why are lysosomes also known as 'scavengers of the cells'?

Which of the following organelles does not have a cell membrane?

Name the cell organelles which are without a membrane.

Draw a plant cell and label the parts which:
$(a)$ determines the function and development of the cell
$(b)$ packages materials coming from the endoplasmic reticulum
$(c)$ provides structural strength to the cell to withstand hypotonic external media without bursting
$(d)$ is the site for many biochemical reactions necessary to sustain life
$(e)$ is a fluid contained inside the nucleus

How is $DNA$ present in a cell which is:
$(a)$ dividing?
$(b)$ not dividing?

Illustrate a plant cell as seen under an electron microscope. How is it different from an animal cell?