Water Cycle
Oxygen Cycle
Carbon Cycle
Nitrogen Cycle
100

The process of water turning from a liquid to a gas is called _________.

What is Evaporation?

100

Plants release oxygen into the air during the process of _____________.

What is Photosynthesis?

100

Carbon is released into the atmosphere in the form of __________ during respiration.

What is CO2?

100

Farmers often add _____________ to the soil to provide plants with extra nitrogen for growth.

What is Fertilizer?

200

After water falls as precipitation, it is gathered in bodies of water such as lakes, rivers, and oceans, in a process known as ____________. 

What is Collection?

200

Animals and humans breathe in oxygen and release ________ __________ during respiration. 

What is Carbon Dioxide?

200

Plants take in carbon dioxide (CO₂) from the atmosphere during photosynthesis to produce _______.

What is Glucose?

200

_____________ is so powerful that when it flashes through the air, it can help convert nitrogen gas into usable forms.

What is Lightning?

300

When water vapor cools and changes back into a liquid, the process is known as ___________.

What is Condensation?

300

The oxygen cycle is closely linked to the __________ cycle, as they both involve the exchange of gases in the atmosphere.

What is Carbon?

300

Carbon dioxide is a greenhouse gas, which contributes to _______ _________ when its concentration in the atmosphere increases.

What is Global Warming?

300

Nitrogen makes up about __________ percent of the Earth's atmosphere.

What is 78%?

400

Plants release water vapor into the air through a process called _________.

What is Transpiration?

400

When organisms die, __________ bacteria help break down their bodies, releasing nutrients and some oxygen back into the environment.

What is Decomposing?

400

Fossil fuels like coal, oil, and natural gas are formed from ____________ ___________ that have been compressed over millions of years.

What are Living Organisms?

400

Some nitrogen in the soil is returned to the atmosphere by special bacteria through a process called ________________.

What is Denitrification?

500

When water falls to the ground and flows over the surface, it is called _______, which can lead to rivers and streams.

What is runoff?

500

In aquatic environments, oxygen is often produced by __________, microscopic plants that float in the water.

What are Phytoplankton? 

500

One solid form of carbon is graphite (like your pencil lead), the other is ______________.

What is Diamond?

500

Plants cannot use nitrogen gas directly, so it must first be converted into forms they can use through a process called __________ _____________.

What is Nitrogen Fixation?

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