How does Amoeba obtain its food?

$(i)$ Why is the cell called the structural and functional unit of life?
$(ii)$ Why is the plasma membrane called a selectively permeable membrane?
$(iii)$ Name the factor which decides the movement of water across the plasma membrane.

Draw any two cell shapes to justify the statement that cells come in a variety of shapes.

The cell organelles having their own $DNA$ and ribosomes are

Which of the following is not a function of the vacuole?

Which type of animal cell lacks both mitochondria and endoplasmic reticulum?