Final answer:
Carbohydrates attached to cell-surface proteins and lipids provide protection, prevent cells from sticking to each other, and aid in cell-cell recognition, performing all the listed functions (D).
Step-by-step explanation:
Carbohydrates attached to cell-surface proteins and lipids, which form glycoproteins and glycolipids, provide a cell with several functions. These functions include:
- (A) Protection from mechanical and chemical damage,
- (B) a slimy coat that prevents cells from sticking to one another,
- (C) a distinctive identity in cell-cell recognition.
Therefore, the answer to the student's question is (D) All of the above.
The carbohydrates on the cell's exterior surface, forming the glycocalyx, also contribute to the cell's interaction with its watery environment and in the cell's ability to obtain substances dissolved in the water. The glycocalyx plays a critical role in several biological processes, including embryonic development, immune defense through self/non-self differentiation, and in facilitating cell to cell adhesion to form tissues.