Biology \"living cell\" In cells, energy is carried by ATP and NADH. ATP is form

Question

Biology "living cell"

In cells, energy is carried by ATP and NADH. ATP is formed by chemical synthesis during oxidative phosphorylation. How is NADH formed? O An electron is added to NAD+ O An electron is removed from NAD+ O ATP is hydrolyzed to generate hydrogen and convert NAD+ to NADH. Hydrogen ions move with their gradient to drive an NADH synthase enzyme. QUESTION 2 1 points Save Answer Glucose is produced in the dark reactions. In the Calvin Cycle, carbon dioxide is taken into the cell to produce glucose. Which of the following must be true of these reactions? O Carbon dioxide is oxidized, while NADPH is reduced. O Carbon dioxide and NADPH are both reduced. O Carbon dioxide and NADPH are both oxidized. O Carbon dioxide is reduced while NADPH is oxidized.

Explanation / Answer

1. Option 1

NADH is formed when an electron is added to NAD+.

Explanation: Nicotinamide adenine dinucleotide (NAD) always gets converted from its oxidized form (NAD+) to its reduced form (NADH) and vice versa during glycolysis, fermentation and oxidative phosphorylation.

2. Option 4

Carbon dioxide is reduced while NADPH is oxidized.

Explanation: In dark reaction, NADPH is oxidized to NADP+ and CO2 is reduced to glucose.

3. Option 4

Oxygen is an irreversible inhibitor of Rubisco.

Explanation: Oxygen and Carbon dioxide compete at the active site of Rubisco. Oxygen binds to the active site of the enzyme and reduces its catalytic activity. Rubisco, is the enzyme that incorporates CO2 into plants during photosynthesis.

4. Option 2

Rubisco operate at a different time than those that allow gas exchange.

Explanation: CAM Plants are able to fix carbon at night so they don't have to keep their stomata open during the day.

5. Option 4 Kinase

Explanation: Kinase is an enzyme that transfers phosphate groups from one molecule to the other. This process is called phosphorylation.

6. Option 2

The wavelength of the light absorbed is less than 680 nm.

Explanation: Chlorophyll b, Xanthophylls, and Carotenes are termed as the antenna pigments in a plant. Many of the carotenes and xanthophylls absorb in the wavelength range of 425 to 475 nm whereas chlorophyll b absorbs light of 453nm and 642 nm maximally.

7. Option c ATP

Explanation: ATP inhibits two essential enzymes in kreb's cycle. They are citrate synthase and isocitrate dehydrogenase. ADP works as an allosteric activator of the enzyme as ATP is formed from ADP. Therefore, the rate of the cycle is reduced when the cell has a high level of ATP.

8. In the absence of oxygen, complex I, cannot give up the electrons to form water in the electron transport chain. This causes NADH to build up at the start of the chain which is a negative regulator of the Kreb's cycle.

9. Light is absorbed, which oxidizes water. The electron is passed through an electron transport chain where energy is harvested to push hydrogen across the membrane into the thylakoid lumen. As those molecules return to the stroma, going against the gradient, the energy is coupled to ATP synthase, causing allosteric changes and producing ATP.

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