Biological oxidation-reduction reactions never involve: a. transfer of e- from one molecule to another. b. formation of free e–. c. transfer of h+ (or h3o+) from one molecule to another. d. formation of free h+ (or h3o+). e. none of the answers is correct

b) Formation of free electron

Explanation:

a) Electrons can by transferred through hydrogen atom, hydride ion or directly as electron. Like NADH and FAD transfer the electrons from substrate to oxygen in respiratory chain.

b) Oxidation mean tranasfer of electron to a molecule that is reduced so there is no concept of free electron in biological system, however there is a concept of oxidative stress due to free radicles.

c) NAD and NADP transfer the H+ from one substrate to other.

D) During the oxidation and reduction of nicotinamide coenzyme the free H+ are produced. the free protons are used to generate ATP in ATP synthase complex of Electron transport chain. The H+ and H30 are present in neutral pure water.

Hoping this might help!!

the core of the sun is so hot and there is so much pressure, nuclear fusion takes place, hydrogen is changed to helium. nuclear fusion creates heat and photons. when the heat reaches the earth it warms the molecules of the atmosphere, and they warm other molecules and so on.