Which of the following is NOT true of proteins? * a. They are obtained from food.

b. They are a component of spider webs.

c. They supply the building blocks needed to repair tissues.

d. They are the main source of energy for cells.

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

Texas has an impending storm, and california is experiencing a water crisis. match the technologies with the state that can use them to reduce the effects eddies natural hazards. texas is the storm cellar and the wood that is crisscrossed. california is the dam and the storage tanks

Which of the organisms listed below performs nitrogen fixation? a. legumes b. plants c. bacteria d. fungi