Question

name
questions: the oxygen cycle
circle the correct answer.

1. nature continually recycles carbon in what we call:

a. the oxygen cycle
b. cellular respiration
c. the carbon cycle
d. photosynthesis

1. why is the carbon cycle intimately tied to the oxygen cycle?

a. one of the most plentiful sources of carbon is carbon dioxide
b. cellular respiration in plants and animals involves both carbon and oxygen
c. combustion, which is part of the carbon cycle, releases oxygen
d. all of the above

1. oxygen accounts for _______ of the human body.

a. 18 % b. 65 %

1. the main creators of oxygen on earth are:

a. plants b. animals
c. humans

1. the carbon dioxide plants and animals exhale is in turn \inhaled\ by plants in a cycle called:

a. the carbon cycle
b. the oxygen cycle
c. cellular respiration
d. the oxygen cycle

1. which of the following processes uses oxygen?

a. cellular respiration
b. decomposition
c. oxidation
d. combustion
e. all of the above

Explanation:

Question 1

The question is about the cycle that recycles carbon. The carbon cycle is specifically for recycling carbon, while the oxygen cycle is for oxygen, cellular respiration and photosynthesis are processes, not the cycle for carbon recycling.

• Option A: Carbon dioxide is a source of carbon, but this doesn't directly tie carbon and oxygen cycles.
• Option B: Cellular respiration in plants and animals uses oxygen and produces carbon dioxide (part of carbon cycle) and vice versa, so it ties the two cycles.
• Option C: Combustion releases carbon dioxide (part of carbon cycle) and uses oxygen, not releases oxygen, so C is wrong.
• So only B is correct.

Oxygen makes up about 65% of the human body (by mass), while 18% is for carbon. So the correct answer is B. (Note: There might be a typo in the original marked option, the correct one is B as oxygen is a major component in water and organic molecules.)

Answer:

C. the carbon cycle

Question 2