Final answer:
Energy in living organisms is primarily obtained by autotrophs through photosynthesis or chemosynthesis, and by heterotrophs through consumption of other organisms.
Step-by-step explanation:
This energy is obtained and utilized through various biological mechanisms. Autotrophs, such as plants, acquire energy directly from sunlight or through chemical reactions to produce organic molecules via photosynthesis or chemosynthesis. Heterotrophs obtain energy by consuming autotrophs or other heterotrophs. The most common energy carrier in cells is Adenosine Triphosphate (ATP), which provides energy for a multitude of cellular functions.
Energy transfer within cells involves biochemical pathways where substances are transformed into others via chemical reactions, with enzymes acting as catalysts to increase efficiency. During these processes, energy is transferred between different molecules. Apart from ATP, other molecules like NADH, FADH2, and glucose also play significant roles in energy transfer during cellular respiration. These molecules help in the conversion of energy stored in food into a form cells can readily use, which is primarily ATP.