What kind of macromolecule is made from amino acids?

nucleic acid
lipid
protein
carbohydrate

Which of the following is the best definition of aerobic respiration? o a. the cellular process that releases energy by breaking down glucose o b. physical activity that involves the repeated motion of large muscle groups o c. physical activity that increases heart rate and breathing rate o d. the cellular process that converts solar energy to chemical energy

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

What is the major difference between a virus and a viroid?