Question

Proteins have many different functions in a cell. Which of the following are possible functions of a protein?
A. Catalysts and building blocks of DNA
B. Enzymes and actively transports molecules across the cell membrance
C. Building blocks of DNA and structural components of cell membrane
D. Components of the cell membrane and main source of energy in cellular respiration

Answer 1

A is partially correct. Catalysts in form of enzymes are made of proteins, yet the building blocks of DNA is amino acid ( to be specific)

B is correct. Enzymes are made of proteins and proteins act as transmembrane protein to actively transport small substances across the cell membrane.

C is partially correct, as the building blocks of DNA should be amino acid, yet it is a structural component of cell membrane by acting as transmembrane protein, receptor protein and peripheral protein etc.

D is partially correct. Protein is a structural component of cell membrane but not the main source of energy in cellular respiration. The main source of energy in cellular respiration should be glucose.

Hence, the answer should be B.
Hope this may help you.