BioInteractive Outputs and Ecological Roles of Photosynthesis

Question 1

What are the overall reactants and products of the photosynthesis equation?

Accepted Answer

Reactants: CO2 + H2O + light; Products: glucose + O2

Answer

The overall equation of photosynthesis is: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.

Question 2

How does photosynthesis contribute to the oxygen content of Earth's atmosphere?

Accepted Answer

Photosynthetic organisms have released O2 as a byproduct for billions of years, creating the modern atmosphere

Answer

The Great Oxygenation Event ~2.4 billion years ago resulted from cyanobacteria releasing O2 via photosynthesis, fundamentally changing Earth's atmosphere.

Question 3

What is gross primary productivity (GPP) in an ecosystem?

Accepted Answer

The total rate of carbon fixation by photosynthesis before subtracting respiration losses

Answer

GPP is the total rate at which photosynthetic organisms fix CO2 into organic compounds, before any energy is consumed by their own cellular respiration.

Question 4

What is net primary productivity (NPP)?

Accepted Answer

GPP minus the carbon lost to plant respiration, representing energy available to consumers

Answer

NPP = GPP − plant respiration; it represents the organic matter actually available to support herbivores and higher trophic levels.

Question 5

How does photosynthesis influence the global carbon cycle?

Accepted Answer

It removes CO2 from the atmosphere and stores carbon in organic molecules, partially offsetting emissions

Answer

Globally, photosynthesis fixes roughly 120 Gt of carbon per year, making it the dominant mechanism for removing atmospheric CO2 and forming the base of the carbon cycle.

BioInteractive - Photosynthesis BioInteractive Test Practice Test

BioInteractive - Photosynthesis BioInteractive Test Practice Test

BioInteractive Outputs and Ecological Roles of Photosynthesis