Final answer:
Thermophilic bacteria adapt to high temperatures primarily by having enzymes with higher optimal temperatures, making modifications to their macromolecular structures, and producing chaperone proteins. Option d) They have enzymes with higher optimal temperatures is the correct answer.
Step-by-step explanation:
Thermophilic bacteria adapt to high temperatures through a variety of mechanisms to ensure their enzymes do not denature. Firstly, their enzymes have a higher optimal temperature, which is a direct adaptation to their hot environment. These thermoenzymes, such as Taq polymerase, are capable of functioning at temperatures that would denature other proteins.
Secondly, thermophilic bacteria have structural differences in their macromolecules, like a higher ratio of saturated lipids in their cell membranes and a higher proportion of guanine-cytosine content in their DNA, to maintain stability. Thirdly, they may produce chaperone proteins, which assist in the proper folding and refolding of other proteins, preventing and correcting misfolded structures that may occur due to heat stress.
The correct option in answer to how certain thermophilic bacteria adapt to high temperatures to prevent enzyme denaturation is (d) 'They have enzymes with higher optimal temperatures.'