Biogeochemical Cycle Review

Producers are

• Organisms that eat only plants

• Organisms that make their own energy/food

• All plants and animals

• Animals only

Why do plants (producers) take CO₂ from the atmosphere?

• to create light energy

• to create glucose

• to create water

• to create carbon dioxide

Nitrogen fixation is

• when nitrogen turns into oxygen

• when nitrogen is fixed at a constant rate and temperature

• when nitrogen is turned into a form that organisms can use

• when nitrogen from fertilizer flows into large bodies of water

This element makes up 78% of gas in the atmosphere:

• oxygen

• carbon

• hydrogen

• nitrogen

An "organic" molecule is a molecule that contains

• hydrogen

• nitrogen

• oxygen

• carbon

How does the human body return carbon to the atmosphere in the carbon cycle?

• waste products

• photosynthesis

• cellular respiration

• formation of glucose

How do plants return carbon to the atmosphere in the carbon cycle?

• waste products

• photosynthesis

• cellular respiration

• formation of glucose

Answer explanation

Plants DO create carbon (in the form of glucose) during photosynthesis, but this carbon is used for processes WITHIN the plant. Remember plants do cellular respiration too, so they are producing some CO2 (carbon dioxide) back into the atmosphere, just like us.

This was a tough question, great work if you were correct!

Which of the following is an example of human impact on the carbon cycle?

• burning fossil fuels

• cutting down trees for lumbar

• driving automobiles

Which of the following are some of the major carbon reservoirs on Earth?

• oceans

• rocks

• living things

• fossil fuels

bacteria fix nitrogen on plant roots. plant roots provide nutrients to bacteria. this is an example of

• mutualism

• commensalism

• competition

• parasitism