6. What would be an expected feature of a plasma membrane that had no integral membrane proteins?
(A) The membrane would be unable to transport sodium ions
(B) The membrane would collapse
(C) The membrane would have no fluidity
(D) The membrane would have no cholesterol
(E) The membrane would not associate with peripheral membrane proteins

2. A protein's _______ structure contains helixes and sheets that result from hydrogen bonding between carboxyl and amino groups of the polypeptide chain. (A) primary (B)secondary (C) tertiary (D) quaternary (E) both secondary and quaternary

3. In animal cells, microtubules grow from (A) the plasma membrane. (B) the outer membrane of the nuclear envelope. (C) centrosomes containing centrioles. (D) dimerization centers located throughout the cytosol. (E) the tips of the chromosomes.

4. The nucleus is to eukaryotes as the _______  is to prokaryotes. (A) plasmid (B) RNA strand (C) ribosome (D)nucleoid (E) nucleolus

5. Two "magic" solutions are sold by a research supply company. 'Magic Solution A" promises to extract all proteins, including integral membrane proteins, from the plasma membrane. "Magic Solution B" promises to simply extract all peripherally associated membrane proteins. What is the likely composition of ''Magic Solution A" and 'Magic Solution B'r? (A) "Solution A" and "Solution B" both contain high salt buffers that disrupt hydrogen bonds and ionic interactions (B) "Solution A" and "Solution B" both include membrane solubilizing detergent(s) (C) "Solution A" is a membrane solubilizing detergent, "Solution B" is a high salt buffer that disrupts hydrogen bonds and ionic interactions (D) "Solution A" is a high salt buffer that disrupts hydrogen bonds and ionic interactions, "Solution B" is a membrane solubilizing detergent (E) "Solution A" is a reducing buffer that disrupts disulfide bonds in proteins, "Solution B" is a membrane solubilizing detergent

7. In the equation, , ATP and heat would be on which side of the reaction? (A) The products because this is an exergonic reaction. (B) The reactants because this is an endergonic reaction. (C) It could appear on either side because this reaction is in equilibrium. (D) The reactants because this is an exergonic reaction. (E) The products because this is an endergonic reaction.

8. How is a gradient of H+ ions formed across the inner mitochondrial membrane? (A) The electron transport chain uses energy from transfer of an electron donated by NADH to pump H across the inner mitochondrial membrane against its electrochemical gradient. (B) ATP synthase generates a H+ gradient across the inner mitochondrial membrane. (C) Electrons move fom NADH to a chain of proteins with lower electronegativities. (D) The electron transport chain uses ATP to pump Ht across the inner mitochondria membrane against its electrochemical gradient. (E) The electron transport chain of proteins contains pores that are leaky to H+.

9. When a cell secretes a growth factor that binds to receptors on its own membrane preventing it from proliferating, this is an example of _______. (A) direct intercellular signaling (B) endocrine signaling (C) contact-dependent signaling (D) paracrine signaling (E) autocrine signaling

10. The monomers of DNA and RNA are (A) monosaccharides. (B) nucleotides. (C) bases (D) nucleic acids. (E) pentoses.

11. Why does a DNA strand grow only in the 5' to 3' direction? (A) because DNA polymerases can only add nucleotides to the 3' end of the growing molecule (B) because DNA polymerases can only add nucleotides to the 5' end of the growing molecule (C) because the DNA molecule only unwinds in the 5' to 3' direction (D) because DNA polymerase requires the addition of a starter nucleotide at the 5' end (E) because the 5'-end is capped

12._______ is to transcription as _______  are to translation. (A) RNA spliceosome； ribosomes (B) RNA polymerase； ribosomes (C) Primer, ribozymes (D) DNA polymerase； RNA polymerase (E) DNA polymerase； ribozymes