Photosynthesis and Cellular Respiration Overview

How are cellular respiration and photosynthesis complementary processes?

They are reverse reactions of each other with the same formula but opposite directions. Cellular respiration is catabolic (ΔG negative) where carbon is oxidized, while photosynthesis is anabolic (ΔG positive) where carbon is reduced.

What is the function of the light reactions in photosynthesis?

To produce NADPH and ATP for the Calvin cycle, and to recover oxygen.

How is light energy converted into chemical energy by pigments?

Through photophosphorylation, which uses light energy to synthesize ATP.

What is resonance in the context of photosystems?

Resonance is the process where electrons transfer to neighboring pigments, increasing the likelihood of exciting a specific pigment for reactions.

What are the components of photosystems?

Photosystems consist of pigments that gather light energy and facilitate electron transfer.

What is the fate of electrons during cyclic and noncyclic electron flow?

In cyclic flow, electrons start and end in the same place. In noncyclic flow, electrons from photosystem I are used to make NADPH, while electrons from photosystem II are replenished by splitting water.

What is photophosphorylation?

The process of transferring light energy into chemical energy, specifically ATP, using pigments.

What is the function of the dark reactions (Calvin cycle)?

To use energy from light reactions to convert CO2 into sugar, which serves as usable energy for plants and animals.

What is the basic stoichiometry for the Calvin cycle?

6 CO2 + 12 NADPH + 18 ATP + 6 H2O → C6H12O6 + 12 NADP + 18 ADP

+ 6 O2

CO2 and H20 enter the cycle, while NADPH and ATP are required for the process.

How is entry to the Calvin cycle regulated by energy levels in the chloroplast?

The activity of rubisco determines whether CO2 can enter the Calvin cycle.

What is photorespiration?

A process that catalyzes the addition of O2 to RuBP, leading to waste energy.