Which of the following statements are true? a. both viruses and bacteria are invisible to the naked eye. b-both viruses and bacteria grow in potentially hazardous foods. c. both viruses and bacteria create spores to them survive. d. thousands of viruses are required to cause a food-borne illness.

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.

Study this image. which statements best describe the rock shown? check all that apply. the grains of this rock are jagged. this rock has several coarse grains. the grains in this rock are very large. this rock has a non-banded pattern. the color of this rock is determined by its texture.

Which statement correctly describes a way that mutations increase the likelihood that a species will survive in a changing environment