cell respiration and photosynthesis

Question 1

stages of cellular respiration

Answer 1

glycolysis ( cytoplasm) breaks glucose into 2 pyrivate, producing 2 ATP nad 2 NADH

Citric Acid cycle ( mitochondira) : completes glucose breakdown, generating NADH and FADH 2

Electron transport chain : uses high energy electrons to create a proton gradient leading to ATP syntehsis via oxidative phosporylation

Question 2

redox reactions and ATP production

Answer 2

Oxidation ( OIL Oxidtion is LOSS) molecules lose electrons

reduction ( RIG reduction is gain) molecules gain electrons

ATP stroes energy in the bonds between phosphate groups

Question 3

Aerobic vs Anaerobic

Answer 3

aerobic : uses O2 as the final electron acceptor, producing 32 ATP per glucose

Anaerobic : uses other electrons acceptors producing less ATP

Fermentation: Converts pyruvate into lactic acid when O2 is not available

Question 4

electron transport chain andf ATP synthase

Answer 4

electron carriers ( NADH, FADH2) donate electrons

protons are pumped across the membrane, creating a gradient

ATP synthase generates ATP as protons flow back into the mitochondria

Question 5

Photosynthesis

Answer 5

n/a

Question 6

Chloroplast structures and light absorbtion

Answer 6

occurs in chloroplasts ( thykaloid membranes and stroma)

light excites electrons in chlorophyll, which drives the photosynthesis

pigments absorb light at different wavelengths

Question 7

Light reactions ( thykaloid membrane)

Answer 7

photosystem II : splits water to release O2 electrons and H +

ETC transfers electrons creating ATP via chemiosmosis

photosystem I: produces NADPH, which carries electrons to the Calvin cycle

Question 8

Calvin cycle (stroma)

Answer 8

phase 1 - Carbon fiaxation : CO2 is fixed by Rubisco

phase 2- reduction : ATP and NADPH convert intermediates into G3P

phase 3 - regeneration: RiBP is regenerated to continue the cycle

Question 9

Photorespiration and alternative pathways

Answer 9

C3 plants : Most common, but lose efficiency in hot , dry climates

C4 platns- Use spatial separation to avoid photorespiration

CAM plants- use temporal separation storing CO2 at night to reduce water loss

Question 10

Explain how ATP is generated in cellular respiration. What role does the electron transport chain play?

Answer 10

ATP is generated through substrate-level phosphorylation in glycolysis and the citric acid cycle, and oxidative phosphorylation in the electron transport chain. The ETC creates a proton gradient, which drives ATP synthase to produce ATP.

Question 11

Why is oxygen essential in cellular respiration? What happens when oxygen is not available?

Answer 11

Oxygen is the final electron acceptor in the ETC. Without oxygen, fermentation occurs instead, regenerating NAD⁺ but producing much less ATP.

Question 12

Discuss the role of redox reactions in both cellular respiration and photosynthesis. How do these processes store and transfer energy?

Answer 12

Redox reactions drive energy transfer: Cellular respiration releases energy by oxidizing glucose, while photosynthesis stores energy by reducing CO₂.

Question 13

A scientist discovers a new organism living in an oxygen-poor environment. What kind of metabolism would you expect it to have? Justify your answer.

Answer 13

The organism would likely use anaerobic respiration or fermentation, using sulfate, nitrate, or other electron acceptors instead of oxygen.