Question:
Why are the epithelial tissues that line an animal's internal organs usually only one or a few cells thick?
(a) To store food efficiently.
(b) To provide maximum strength.
(c) To allow quick exchange of materials across them.
(d) To reduce friction.
Answer:
Verified
(c) To allow quick exchange of materials across them.
Explanation: The epithelial tissues lining many internal organs are usually only one or a few cells thick to minimise the distance through which substances need to diffuse. This enables rapid and efficient exchange of materials such as gases, nutrients and wastes. For example, in the lungs, a thin epithelium allows quick exchange of oxygen and carbon dioxide, while in the small intestine it helps in efficient absorption of nutrients.
