carbon and nitrogen cycle

How does carbon in a grass plant get into a lion?

• The lion eats an antelope that ate the grass

• Carbon from grass doesn't end up in a lion.

• The lion absorbs the carbon given off by transpiration

• The lion breathes in carbon given out by the plant

Which of the following add carbon dioxide to the atmosphere?

• volcanoes
• combustion of fossil fuels
• animal and plant respiration
• all of these

Plants release water into the atmosphere by 

• photosynthesis
• transpiration
• perspiration
• respiration

What is happening at 1?

• respiration: releasing CO₂
• decomposing CO₂ in the soil
• photosynthesis: absorbing CO₂
• turning CO₂ from the atmosphere into organic molecules

How much of the atmosphere is composed of nitrogen gas?

• 87%
• 38%
• 78%
• 21%

Why do all organisms need nitrogen?

• To live and grow 
• To build phosphorus
• To make oxygen levels grow
• To help blood circulate better

How nitrogen is "fixed" into useable form for plants

• only through action of bacteria
• only through lightning
• through action of bacteria & lightning
• through photosynthesis

When humans burn fossil fuels, most of the carbon quickly enters the                       as carbon dioxide.

• Water
• Atmosphere
• Sun
• Air

Which one of these does not add CO2 to the atmosphere?

• cooking with gas
• planting trees
• burning wood
• riding in a bus

Which describes the relationship between plants and animals in the carbon cycle?

• Plants produce and release oxygen that animals need

• Plants produce and release carbon dioxide that animals need

• Animals produce and release oxygen that plants need

• Animals produce oxygen that plants turn into carbon dioxide