Which is the most serious form of skin cancer?

A. Increase the size of body structures: While tissue growth can contribute to body size, its primary function is not just increasing size but carrying out specific physiological roles.

B. Perform common functions: Tissues consist of similar cells that work together to perform specific functions, such as muscle contraction, nerve signaling, or support.

C. Deliver messages: Only nervous tissue specializes in transmitting messages, but other tissues have different functions.

D. Fight against diseases: The immune system fights diseases, but not all tissues are involved in this function.

A. For fluid balance: Lipids do not play a direct role in maintaining fluid balance; electrolytes and plasma proteins like albumin regulate this function.

B. As a component of the myelin sheath: Lipids, particularly phospholipids and cholesterol, are essential for forming the myelin sheath, which insulates nerve fibers and facilitates efficient nerve conduction.

C. Component of hemoglobin: Hemoglobin is composed of iron and protein (globin chains), not lipids.

D. As a component of the cell membrane: Cell membranes are composed of a lipid bilayer (phospholipids and cholesterol), which helps maintain structural integrity and fluidity.

E. As an energy source: Lipids provide a concentrated energy source, yielding 9 kcal per gram, which is more than carbohydrates (4 kcal/g).