Cycles of Matter in Ecosystems: Part 1 (Nitrogen)

Multiple Choice

Why is nitrogen essential for plant growth?

• Because it is used by plants and animals to make proteins

• Because it is used by plants and animals to make carbohydrates

• Because it is used to make fats and minerals.

• Because it is used to make vitamins

Multiple Choice

Which of the following is NOT a component of soil as shown in the diagram?

• Plastic

• Mineral

• Air

• Water

Multiple Select

Select all the correct statements about the conversion of nitrogen by bacteria.

• Bacteria convert nitrogen gas from the air into ammonia or ammonium.

• Bacteria convert ammonia and ammonium into nitrate.

• Nitrogen fixation means converting nitrogen gas to ammonia and ammonium.

• Plants can use ammonia and nitrate to make proteins.

Multiple Choice

Why are legumes considered self-sufficient (can take care of themselves) in getting nitrogen?

• They have bacteria in their roots that convert nitrogen gas to nitrate.

• They absorb nitrogen gas directly from the air through their leaves.

• They do not require nitrogen for growth because they use minerals instead.

• They produce their own ammonium compounds.

Multiple Choice

How do animals contribute to the nitrogen cycle?

• By releasing nitrogen as waste products

• By absorbing nitrogen directly from the air

• By converting nitrates into nitrogen gas

• By producing root nodules

Multiple Choice

Which organisms are the most responsible for breaking down dead organisms and returning nitrogen to the soil?

• Fungi and bacteria

• Plants and animals

• Insects and birds

• Fish and amphibians

Multiple Select

Which of the following are steps in the nitrogen cycle as shown in the diagram?

• Nitrogen-fixing bacteria convert unusable nitrogen to usable forms

• Animals eat plants

• Plants release nitrogen gas into the atmosphere

• Lightning changes nitrogen gas into nitrogen compounds