Which describes an oxidation reaction that occurs during cellular respiration? water loses electrons and hydrogen to form oxygen. glucose loses electrons and hydrogen to form carbon dioxide. carbon dioxide gains electrons and hydrogen to form glucose. oxygen gains electrons and hydrogen to form water.

Option 4; Oxygen gains electrons and hydrogen to form water.

Respiration is a process where glucose is used and energy is released stored in this molecule. Oxygen is used during respiration as well and it gains the electrons and hydrogen to form water. And, gain of electrons is an oxidation reaction. So answer is option 4.

Since, oxygen is consumed during respiration, option 1 is incorrect.

Loss of electrons is reduction, so option 2 is also incorrect.

Glucose is used in respiration, thus option 3 is incorrect.

dna is made up of six smaller molecules -- a five carbon sugar called deoxyribose, a phosphate molecule and four different nitrogenous bases (adenine, thymine, cytosine and guanine).