Question

27. What is being reduced in the following reaction? Pyruvate + NADH = Lactate + NAD a. oxygen 6. NADH c. NAD d. lactate pyruvate

Answer 1

Ans 27: Pyruvate- In the above reaction the reactants involved are pyruvate and NADH, also proton plays a role here. The reactants react to give the products i.e, lactate (or lactic acid) and NAD⁺. This is a fermentation reaction and the process results in the reduction of the pyruvate to form a lactate and the oxidation of NADH leads to the formation of NAD⁺. In simple term pyruvate is being reduced and NADH is oxidised.

Ans 28: Thylakoid Space- The light dependent reactions primarily occurs in the thylakoid membrane present in the chloroplast. They are involved in taking the energy from light and uses it to make the molecules like NADPH and ATP.

The thylakoid space is the space present inside the thylakoids. Not to be confused that the light dependent reactions occur in the thylakoid membrane and not in the thylakoid space. This thylakoid space comprises of thylakoid lumen, which provides structure and builds up a concentration gradient of protons at the time of photosynthesis.
During photosynthesis the chlorophylls absorbs the light energy causing it to lose an electron where it is detected by the primary electron acceptor distributing it into different complex of proteins passing from one molecule to the other (electron transport chain). During the process the proteins pump the hydrogen ions from one side of the membrane towards the other. The resulting high concentration of hydrogen ions that has been pumped into the inner thylakoid space are then used to make the ATP.