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

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

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

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+.

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

13. Which sequence of events CORRECTLY describes the initiation and elongation steps of translation in prokaryotic cells?(1) initiator tRNA binds start codon on mRNA(2) small ribosomal subunit binds to mRNA(3) large ribosomal subunit binds(4) tRNA entry and peptidyl transfer reaction(5) translocation of ribosome and release of tRNA(A) 1,2,3,4,5(B) 1,2,3,5,4(C) 1,3,2,4,5(D) 2,3,1,5,4(E) 2,1,3,4,5

14. Genes organized into an operon are beneficial to certain bacteria because the operon allows for (A) differential regulation of individual genes that encode proteins with a common function. (B) coordinated regulation of a group of genes that encode proteins with a common function. (C) separate regulation of individual genes that encode proteins with different functions. (D) coordinated regulation of a group of genes that encode proteins with different functions. (E) coordinated regulation of a group of proteins involved in numerous cellular activities.

15. DNA methylation (A) increases transcription. (B) inhibits transcription. (C) increases crossover events. (D) decreases crossover events. (E) increases post-translational modification of proteins.