6. Which one of the following statements is NOT true?
(A)Receptor tyrosine kinases generally activate a single transduction pathway.
(B) RTKs transfers a phosphate group from ATP to the tyrosine of a substrate protein.
(C) The cytoplasmic tail of an RTK has multiple tyrosines.
(D) Dimerization or formation of large clusters of RTKs happen when they are activated.
(E) All of the above.

2. Amino acids can be distinguished from one another by __________.(A) the number of R groups found on the amino acid molecules.(B) the chemical properties of their R groups. (C)the type of bond between the R group and the rest of the amino acid molecule.(D) the chemical properties of their amino and carboxyl groups. (E)All of the choices are correct.

3. Every subunit (nucleotide) of a polynucleotide contains ______ negative charge(s). (A)0(B) 1 (C)2 (D) 3 (E)4

4. Considering the following statements about active transport, which of these statements are true? I. Facilitated diffusion is a special kind of active transport that does not require energy. II. Active transport requires energy, usually in the form of ATP hydrolysis. III. Active transport moves substances down their concentration gradients. IV. All proteins involved in active transport are carrier proteins V. Ion channels facilitate the active transport of ions (A)II and IV(B) I, II, III and IV (C)II, IV and V (D) I, II and IV (E)All

5. How do the reaction centers of photosystem I, and II differ? (A)chlorophyll a is found in photosystem I, and chlorophyll b in photosystem II.(B) They preferentially absorb slightly different wavelengths of light. (C)One is located in the thylakoid membrane, and the other in the stroma. (D) Only photosystem I is found in the thylakoid membranes. (E)None of the above.

7. Who discovered the citric acid cycle? (A)Albert Einstein(B) Membrane proteins (C)Hans Krebs (D) Albert Lehninger (E)Melvin Calvin

8. Which one of the following statements is NOT true for apoptosis?(A)Signals that trigger apoptosis can come from outside or inside the cells.(B) In apoptotic cells, organelles, but not DNA, are fragmented. (C)The cell's parts are packaged up in vesicles that are engulfed and digested by specialized scavenger cells.(D) Cell shrinks and becomes lobed. (E)None of the above.

9. Which one of the following statements is NOT true?(A)Intracellular receptors are found in either the cytoplasm or nucleus of target cells.(B) Ligands of intracellular receptors are hydrophobic or small. (C)Most intracellular receptors regulate translation. (D) Intracellular receptors and their ligands form complexes to carry out specific functions. (E)All of the above.

10. In a photosystem, clusters of chlorophyll b, and carotenoid pigments function most like____________.(A) an electrical generator(B) an antenna (C)a propeller on a motorboat (D) a windmill (E)a spring

11. Sex determination in mammals is due to the SRY gene found on the Y chromosome. Which of the following situations could allow a person with an XX karyotype to develop a male phenotype? (A) the loss of the SRY gene from an autosome (B) translocation of SRY to an X chromosome (C)the presence of an extra autosomal chromosome (D) the presence of one normal and one shortened (deleted) X chromosome (E)None of the above.

12. What is the main advantage of the C4 and CAM photosynthesis strategies over the C3 strategy? (A) They help the plant conserve water and synthesize glucose efficiently under hot, dry conditions. (B) They allow the plant to fix carbon more efficiently under conditions of low atmospheric CO2. (C)They allow the plant to fix carbon more efficiently in dim or cool conditions. (D) They make it possible for the plant to use the Calvin cycle at night and during the day. (E)They allow the plant to avoid photorespiration by producing a four-carbon sugar in place of glucose.