Unit 2 - Photosynthesis: Plants & Air

Question 1

HOW do plants cycle the gases in the air?

OR

HOW do plants and animals depend on each other for oxygen and carbon dioxide?

Answer 1

Plants not only make FOOD… they also make OXYGEN.

During photosynthesis, plants use CARBON DIOXIDE from the air and release OXYGEN.

Animals and people breath in OXYGEN from the air and give out CARBON DIOXIDE.

Plants use this carbon dioxide for PHOTOSYNTHESIS.

Plants and animals thus DEPEND on each other for oxygen and carbon dioxide.

Question 2

What is oxygen?

Answer 2

A gas in the air that plants and animals NEED when they BREATHE; plants make it.

Question 3

What is carbon dioxide?

Answer 3

A gas in the air that plants and animals GIVE OFF when they breath; plants need it for photosynthesis.

Question 4

Do plants need oxygen?

Answer 4

Yes, plants need oxygen.

AT NIGHT:

• Plants only breath.
• Use little oxygen and release little carbon dioxide.

DAY TIME:

• Plants breathe AND carry out PHOTOSYNTHESIS.
• Use MORE carbon dioxide for photosynthesis than for breathing
• Make MORE oxygen than they use.