Give the number of protons, neutrons and electrons in the lithium atom shown in the diagram above,
Number of protons
Number of neutrons
Number of electrons

Which best describes a gene? a. a sister chromatid b. a chromosome c. a tetrad d. a piece of a chromosome

Explain how paleontologists use trilobite fossils as index fossils for various geologic time periods.

Do the following statements describe actin, myosin, both of the proteins or neither of the proteins? (a) contains a binding site for calcium (b) found in the i band (c) exists in a globular (g) form and a filamentous (f) form (d) contains a binding site for atp (e) is a component of the thin filament (f) is a component of the thick filament