Earl Sutherland won the Nobel prize for discovering how epinephrine stimulates the breakdown of glycogen, a molecule that belongs to the carbohydrate family of macromolecules. Glycogen is abundant in liver and in muscle cells and is stored in glycogen granules. When epinephrine interacts with the liver cells it triggers a signal transduction cascade that leads to activation of glycogen phosphorylase and production of glucose-1-phosphate molecules. The glucose-1-phosphate molecules are then used for glycolysis to produce energy in the liver cell. To decipher the signal transduction pathway that triggers the breakdown of glycogen Sutherland and his colleagues used a test tube, the enzyme glycogen phosphorylase, epinephrine and glycogen. In this experiment he observed that no glucose-1-phosphate was formed. Why do you think this happened?

Over the past 60 years, many amphibian species have experienced significant population declines and some species have become extinct. scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. however, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. these global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. in switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. chytridiomycosis is a fungal disease first identified in 1998 as a cause of massive amphibian deaths. in some severely impacted populations, a few individuals have survived, perhaps because of some natural resistance. if these resistant individuals continue to survive and prosper, new resistant populations might emerge. this would be an example of the founder effect artificial selection genetic drift natural selection sexual selection

There is a liquid capsule inside a cup full of liquid. the cup full of liquid has salt in it and the liquid capsule has no salt in it. in which direction will the solvent flow? a. the salt does not have to move b. from the capsule to the larger cup c. equally between the capsule and the cup d. from the larger cup to the capsule

Where does oogenesis take place ? seminiferous tubules fallopian tubes ovaries uterus