Question

(iv) Why cell membrane is semipermeable in nature?
(w) How facilitated diffusion is different from active transport?
the tructural and functional unit of​

Answer 1

Answer: Cell membranes serve as barriers and gatekeepers. They are semi-permeable, which means that some molecules can diffuse across the lipid bilayer but others cannot. Small hydrophobic molecules and gases like oxygen and carbon dioxide cross membranes rapidly.

Answer 2

• The membrane is selectively permeable because substances do not cross it indiscriminately. Some molecules, such as hydrocarbons and oxygen can cross the membrane. Many large molecules (such as glucose and other sugars) cannot. Water can pass through between the lipids.

• The facilitated diffusion takes place along the concentration gradient and does not require energy. On the other hand, in active transport molecules move against the concentration gradient and this process requires energy.

• The cell is the basic structural and functional unit of life. Cells are independent, single-celled organisms that take in nutrients, excrete wastes, detect and respond to their environment, move, breathe, grow, and reproduce.