Oxygen Cycles

Oxygen is a living element that humans and animals require to live. 

• True 
• False

What does an "exchange of gases" mean?

• It means that gases are apart of everything. 
• It means that orange juice is an upside down milkshake with a missing tail.
• It means that humans and plants trade gases back and forth.
• It means that carbon in apart of all living things. 

Why is the CO2 and O2 cycle considered to be a cycle?

• there is a exchange of gases
• the trees use it and trees are apart of all cycles
• there is a continuous exchange of gases

Which type of organism gets its energy directly from the Sun?

• producer
• consumer
• composer
• decomposer

Which statement is true about the carbon dioxide-oxygen cycle?

• animals breathe in nitrogen and release oxygen which is used by plants
• animals breathe in oxygen and release carbon dioxide which is used by plants
• animals breathe in nitrogen and release carbon dioxide which is used by plants
• animals breathe in carbon dioxide and release oxygen which is used by plants

If all the trees on Earth were destroyed, what would be the effect on humans?

• there would be a lack of food
• there would be a lack of oxygen
• there would be a lack of fresh water
• there would be a lack of carbon dioxide

The class decided to have a terrarium.  The teacher says it is important to include both plants and animals.  Why is it necessary to include both plants and animals?

• plants provide food for the animals and animals provide water for the plants
• plants provide water for the animals and animals provide food for the plants
• plants provide carbon dioxide for the animals and animals provide oxygen for the plants
• plants provide oxygen for animals and the animals provide carbon dioxide for the plants

Animals and plants use substances that cycle through the environment.  Which substance is needed by plants to survive and is released into the environment by animals?

• oxygen
• sugar
• salt
• carbon dioxide

If the removal of many plants and trees increase in a forest, what effect could this have on the carbon dioxide and oxygen cycle?

• CO2 levels decrease
• CO2 levels increase
• Nitrogen levels decrease
• Oxygen levels increase

The CO2/O cycle is important to animals because it provides

• a gas they take in when breathing
• chemicals that build bones
• energy they need to move
• fresh water for their survival