The text claims that the evolution of an oxygen-rich atmosphere paved the way for increasingly efficient cellular respiration and higher growth rates in organisms. Explain.

A biochemist wanted to study how various substances were used in cellular respiration. In one experiment, she allowed a mouse to breathe air containing O₂ 'labeled' by a particular isotope. In the mouse, the labeled oxygen first showed up in

a. ATP

b. NADH

c. CO₂

d. H₂O

If you were to expose cells that are undergoing aerobic respiration to a radioactive oxygen isotope in the form of O₂, which of the following molecules would you expect to be radiolabeled?

a. Pyruvate

b. Water

c. NADH

d. CO₂

Cellular respiration involves ________.

a. The aerobic metabolism of sugars in the mitochondria by a process called glycolysis.

b. An electron transport chain that releases carbon dioxide.

c. The synthesis of ATP, which is driven by the rushing of protons through an ATP synthase.

d. Electron carriers that bring electrons to the citric acid cycle; e. the production of water during the citric acid cycle.