Index fossils are
A. Fossils of the species that still exist today
B. Fossils that are found in limestone
C. Relatively rare and difficult to find
D. Imprints of organisms known to have lived during a specific time period

Before the can be observed by using a transmission electron microscope, cells are sliced into very thin sections. what disadvantage does this procedure present in the study of cellular parts

Which best describes the digestive system of arthropods? a incomplete, two openings b complete, one opening c two-way, one opening d one-way, two openings

Select the correct answer. which mutation is harmful to the organism? a. a mutation allowing moths to camouflage better on blackened tree bark b. a mutation making staphylococcus aureus resistant to the antibiotic methicillin c. a mutation inhibiting human immunodeficiency virus from attaching to and entering the cell d. a mutation causing uncontrolled cell division e. a mutation giving plant leaves a bitter taste to discourage herbivores from eating them