Radioisotopes tell scientists that earth is how old? a. 65 million years b. 500 million years c. 4.5 billion years d. 13.4 billion years

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.

answer; aerobic conditions; citric acid cycle (krebs cycle) electron transport chain;         anaerobic conditions; fermentation; both glycolysis;