Photosynthesis Review and Key Concepts

Final electron acceptor in photosynthesis

NADPH

Overall equation for photosynthesis

6 CO2 + 6 H2O + solar energy → C6H12O6 + 6 O2

C4 plant example

Any specific example of a C4 plant

C4 and CAM plants adaptations

Allow them to fix carbon efficiently under specific environmental conditions

Reason for cyclic photophosphorylation

Plants switch to cyclic rather than noncyclic photophosphorylation for energy production under certain conditions

Source of oxygen in glucose during Calvin cycle

The oxygen originally comes from water

Products of light-dependent reactions

ATP and NADPH

Difference in carbon fixation between C4 and CAM plants

C4 plants fix carbon in a different pathway compared to CAM plants

Location of chemiosmosis

In the thylakoid membrane

Calvin cycle turns for one glucose molecule

Six turns of the Calvin cycle are required to make one molecule of glucose

Gas released during light-dependent reactions

Oxygen

Molecule source of released gas

Water

Effect of photosynthesis stopping on Earth

Most living organisms would face extinction due to lack of oxygen and food sources

Summary of light-dependent reactions

Light energy is converted into chemical energy in the form of ATP and NADPH

Summary of light-independent reactions

Carbon dioxide is fixed into glucose using ATP and NADPH produced in light-dependent reactions

NADPH

A coenzyme that carries electrons and hydrogen ions during photosynthesis.

Photosynthesis Equation

6 CO2 + 6 H2O + solar energy → C6H12O6 + 6 O2

Light Absorption

Red and blue-violet wavelengths are primarily absorbed during photosynthesis.

C4 Plants

Plants that utilize a four-carbon compound for carbon fixation, such as corn and sugar cane.

Adaptation of C4 Plants

Photosynthesize in hot, dry conditions; avoid photorespiration.

Calvin Cycle ATP Requirement

C4 plants need more ATP than NADPH to perform the Calvin cycle.

Oxygen Release

Oxygen is released to the atmosphere as a by-product of photosynthesis.

Photosynthesis Products

The main products of photosynthesis are O2, ATP, and NADPH.

C4 vs CAM Plants

In C4 plants, the Calvin cycle occurs in a separate cell from carbon fixation; in CAM plants, both occur in the mesophyll cell at different times.

Cellular Locations

Photosynthesis occurs in mitochondria or chloroplasts.

Calvin Cycle Turns

Two turns of the Calvin cycle produce one 3-carbon molecule.

Photosynthesis Processes

Splitting of water occurs in the thylakoid space; the Calvin cycle occurs in the stroma.

Oxygen Production

Oxygen is released as a by-product during the light reactions of photosynthesis.

Oxidation in Photosynthesis

When a molecule loses an electron, it is said to be oxidized.

Reduction in Photosynthesis

When a molecule gains an electron, it is said to be reduced and gains energy.

Carbon Cycle in Calvin Cycle

For each carbon atom released from the Calvin cycle, one CO2 molecule must enter; to produce PGAL, 3 CO2 must enter; to produce glucose, 6 CO2 must enter.

Impact of Stopping Photosynthesis

If photosynthesis stopped, most living organisms would die due to a shortage of energy or oxygen.

Light Energy Absorption

Light energy is absorbed by electrons from water splitting, supplying energy for ATP and NADP-H formation.

Calvin Cycle Function

Molecules of CO2 enter the Calvin cycle, where they are reduced using energy from ATP and NADP-H to construct high-energy molecules of PGAL (G3P).