Which organelle is known as the powerhouse of the cell? Why?

Why is the plasma membrane called a selectively permeable membrane?

Carry out the following osmosis experiment:
Take four peeled potato halves and scoop each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,
$(a)$ Keep cup $A$ empty.
$(b)$ Put one teaspoon sugar in cup $B$.
$(c)$ Put one teaspoon salt in cup $C$.
$(d)$ Put one teaspoon sugar in the boiled potato cup $D$.
Keep these for two hours. Then observe the four potato cups and answer the following:
$(i)$ Explain why water gathers in the hollowed portion of $B$ and $C$.
$(ii)$ Why is potato $A$ necessary for this experiment?
$(iii)$ Explain why water does not gather in the hollowed out portions of $A$ and $D$.

What would happen to the life of a cell if there was no Golgi apparatus?

Who discovered cells,and how?

Why is the cell called the structural and functional unit of life?