Name two unicellular animals.

$(i)$ 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.

Describe the structure of mitochondria with special reference to its membrane covering.

Write two statements to show that lysosomes are aptly called the suicide bags of the cell.

$A$ person takes a concentrated solution of salt; after some time,he starts vomiting. What is the phenomenon responsible for this situation? Explain.

Differentiate between prokaryotic and eukaryotic cells.