Carbon dioxide makes up less than
1 percent of Earth's atmosphere, and
oxygen makes up about 20 percent.
These percentages are maintained
most directly by
(1) respiration and photosynthesis
(2) the ozone shield
(3) synthesis and digestion
(4) energy recycling in ecosystems
1 percent of Earth's atmosphere, and
oxygen makes up about 20 percent.
These percentages are maintained
most directly by
(1) respiration and photosynthesis
(2) the ozone shield
(3) synthesis and digestion
(4) energy recycling in ecosystems