Unit 3: Nutrient Cycles

The model is part of the carbon cycle. What molecules would you expect to find in box D?

• nitrogen gas

• carbon dioxide

• glucose

• oxygen gas

The model is part of the carbon cycle. What molecules would you expect to find in box C?

• glucose

• carbon dioxide

• methane

• water

The model is part of the carbon cycle. What type of organisms would be in box A?

• plant

• human

• animal

• none of these

The model is part of the carbon cycle. What is the process in box B in the diagram?

• aerobic cellular respiration

• fermentation

• anaerobic respiration

• photosynthesis

Calculate the net change of carbon atoms going into and out of the atmosphere to answer the following question. What impact will this change have on the atmosphere?

• Carbon dioxide is a greenhouse gas that releases heat to outer space, cooling the atmosphere. The increase of CO2 is making the atmosphere cooler.

• Carbon dioxide is a greenhouse gas that traps and holds heat, warming the atmosphere. The increase of CO2 is making the atmosphere warmer.

• Carbon dioxide is a greenhouse gas that releases heat to outer space, cooling the atmosphere. The decrease of CO2 is making the atmosphere cooler.

• Carbon dioxide is a greenhouse gas that traps and holds heat, warming the atmosphere. The decrease of CO2 is making the atmosphere warmer.

During a forest fire, most of the carbon in a tree is released into which reservoir?

• atmosphere

• soil

• animals

• oceans

There is scientific evidence from ice cores showing that the concentration of carbon dioxide in the atmosphere is more now than it was several hundred years ago. Many scientists hypothesize that the increase in concentration is due to the burning of fossil fuels. Which of the following best explains the increases in carbon in the atmosphere?

• Carbon that was removed from the atmosphere because of photosynthesis is released back into the atmosphere because of respiration.

• Carbon that was stored in trees is released into the atmosphere during a forest fire.

• Carbon stays in the fossil fuel during combustion and causes the atmosphere to maintain its concentration of carbon dioxide.

• Carbon that was not part of the normal cycle because it was trapped in fossil fuels buried in the ground became released into the atmosphere when a fossil fuel was burned.

How do animals get their nitrogen that they need?

• They use their lungs to breathe it out of the air.

• They have to eat plants or other animals that ate those plants.

• They absorb it from the soil.

• They get it by eating the soil bacteria.

What do legumes (like clover and kudzu) have on their roots?

• nodules full of nitrogen fixing bacteria

• nodules full of seeds

• nodules full of carbon dioxide

• nodules full of trace gases

Select the correct path of nitrogen moving through the nitrogen cycle.

• air--> animals--> plants--> bacteria

• air--> bacteria--> plants--> animals

• plants --> air --> animals

• bacteria --> air --> plants