The conversion process that transforms the energy of sunlight into chemical energy stored in sugars and other organic molecules is called photosynthesis. Photosynthesis nourishes almost the entire living world directly or indirectly.
Respiration breaks the fuel down, using oxygen and generating ATP. The waste products of this type of respiration, carbon dioxide and water (H2O), are the raw materials for photosynthesis.
Enzymes speed up metabolic reactions by lowering energy barriers. Each enzyme has an optimal temperature and pH. Regulation of enzyme activity helps control metabolism.
The totality of an organism’s chemical reactions is called metabolism. Metabolism is an emergent property of life that arises from orderly interactions between molecules.
Passive transport is diffusion of a substance across a membrane with no energy investment. Active transport uses energy to move solutes against their gradients. Bulk transport across the plasma membrane occurs by exocytosis and endocytosis.