Question
Why are the epithelial tissues that line an animal’s internal organs usually only one or a few cells thick?
(i) To store food efficiently.
(ii) To provide maximum strength.
(iii) To allow quick exchange of materials across them.
(iv) To reduce friction.
Answer
The correct answer is: To allow quick exchange of materials across them.
Epithelial tissue is mostly thin cells or a few cells thick because it helps to quickly exchange the substance across them such as oxygen, nutrients, waste product.
Explanation:
A thin layer means a shorter distance is covered by the substance for exchange. so it happen quickly.
For example:
- 🫁 In the lungs. Oxygen needs to quickly pass from the air sacs into the blood and also carbon dioxide passes out from it.
- 🩸 In blood vessels. The thin lining is made up of epithelial tissue that helps substances move between the blood and surrounding tissues.
- 🍎 In the intestine. The nutrients need to pass through the lining and enter into the blood.
