Exothermic reaction is when the system releases energy to the surrounding, the energy (in the perspective of the system) will have a sign of negative, as the system is transferring energy towards the surrounding.
Endothermic reaction is when the system is absorbing energy from the surrounding, the energy (in the perspective of the system) will have a sign of positive, as energy is transferred to the system.
The answer is oxidation.
That is in the redox fueling reaction,
succinate + NAD ↔fumarate + NADPH, the succinate molecule is undergoing oxidation.
As succinate molecule is providing electrons to NAD, so that it can be reduced from NAD to NADPH. So it is losing electrons and undergoing oxidation.
So the answer is oxidation.
The word that best fits is frequency. The sentence is The frequency of a wave is a measure of the amount of energy it carries. There is a direct relationship between frequency and energy of a wave. The constant of proportionality is h, Planck's constant. So, Energy = h * frequency. So, the answer is frequency.<span> Although you should know that wavelength is related to frequency and so it is also a measure of the amount of energy and it should also be other valid answer.</span>
