cytochromes are critical participants in the electron transport chains used in photosynthesis and cellular respiration. how do cytochromes donate and accept electrons?

relative humidity is a measure of the amount of moisture in the air relative to the total amount of moisture the air can hold.

so d

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.