Which greenhouse gas is emitted by cows?
A) CH4
B) none of the above
C) H2O
D) CO2

Which codon is the code for the amino acid histidine (his)?

The large increase in atmospheric carbon dioxide in the last 50 years most likely comes from a. an increase in cellular respiration b. increased decomposition by bacteria c. an increase in the burning of fossil fuels d. an increase in photosynthesis

Which term describes a normal value for something in the body? a.homeostasis b.set point c.feedback loop d.integration center