What is the primary role of photosynthesis in the carbon cycle?

It fixes atmospheric carbon into organic compounds.

It releases stored chemical energy by breaking down organic matter with oxygen.

It decomposes dead organisms, returning their carbon to the soil and air.

It converts nitrogen gas into a usable form for plants to absorb.

A small sapling grows into a massive tree over many years. What is the original source of most of the carbon atoms that make up the tree's new mass?

Minerals and nutrients absorbed from the soil through the roots.

Sunlight that is absorbed by the leaves and converted into matter.

Carbon dioxide gas from the atmosphere taken in by the leaves.

Water that is transported up from the ground through the trunk.

Carbon that exists as a gas in the Earth's atmosphere.

The non-living physical and chemical components of an ecosystem.

Carbon stored in the tissues of living or once-living organisms.

Energy from the sun that is used to power life processes on Earth.

It is the most abundant gas in the atmosphere.

It provides the primary source of energy for cells.

It forms the backbone of organic molecules.

It is the only element found in both living and non-living things.

A volcano erupting and releasing gases into the atmosphere.

A dead tree decomposing on the forest floor.

An animal exhaling after running.

A blade of grass making its own food using sunlight.