Coleman hypothesized that the product of the ob+ gene was the appetite-suppressing hormone. Therefore, the homozygous ob/ob mutant would be unable to synthesize that hormone, and its circulating level would be zero. Coleman also hypothesized that the product of the db+ gene was the the receptor for the appetite-suppressing hormone. Therefore, the homozygous db?db mutant would be able to respond to it. It would eat excessively and produce large amounts of body fat, which in turn would produce large amounts of appetite-suppressing hormone. In the absence of a receptor, the db/db mutant's hormone level would remain abnormally high.
Both the ob/ob mutant and the db/db mutant are obese because neither is capable of suppressing its appetite. The ob/ob mutant produces no appetite suppressing hormone and so eats excessively. The db/db mutant cannot respond to the appetite-suppressing hormone and therefore eats excessively.
Anaerobic respiration uses electron receptors other than oxygen molecules. Anaerobic respiration produces a maximum of 2 ATP (Adenosine triphosphate) per glucose!
B because cactus' are usually in a dry environment, they close their stomata during the day to keep water vapor from leaving the plant. Instead they do their processes at night to avoid extreme water loss.
The mass is increased as two things are added together so the two masses of the two substances are added together.
