Most cells cannot harness heat to perform work because

a. cells do not have much heat; they are relatively cool.

b. heat must remain constant during work.

c. heat is not a form of energy.

d. temperature is usually uniform throughout a cell.

e. heat can never be used to do work.

The correct answer is d. temperature is usually uniform throughout a cell.

Explanation:

Cell utilise chemical energy for carrying out its metabolism. The chief form of chemical energy used by cells is ATP or adenosine triphosphate that stores a lot of energy in the phosphate-ester bonds. Chemical energy is also stored in the form of lipid or fatty acids. In the cells release of heat energy is not possible because, other than chemical energy cells stores energy in the form of electrochemical gradient (gradient of specific ions like K⁺ or Na⁺), proton gradient, etc, across membranes. This is because cells require a specific temperature, that is, the body temperature, to carry out metabolism at an optimal rate. If heat energy is utilised or released in any chemical process it can cause alteration in body temperature, thereby affecting the process of metabolism.