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
A)
respiration and photosynthesis
the ozone shield
C)
synthesis and digestion
D)
energy recycling in ecosystems

Which event would lead to primary succession of a forest?

Each hereditary trait corresponds to

Which of these has happened to your food by the time it reaches your small intestine? a. all the macromolecules have been broken down completely. b. lipids and starches have been partially broken down. c. starches and proteins have been partially broken down. d. proteins and lipids have been broken down into subunits.