Q: Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only do what? Choices: - vibrate - pull - expand - contract A:
contract

Q: What are electrons at the outermost energy level of an atom are called? Choices: - core electrons - ions - shell electrons - valence electrons A:
valence electrons

Q: What occurs when a former inhabited area gets disturbed? Choices: - tertiary succession - primary succession - tropical succession - secondary succession A:
secondary succession

Q: According to rutherford, where is the vast majority of the mass of an atom located? Choices: - the cytoplasm - the shell - the electrons - the nucleus A:
the nucleus