27. The action potential does not move backward from the terminal to hillock because
(A) close of the inactivation gate of channels
(B) delayed open of the channels
(C) close of the inactivation gate of channels
(D) increase of the threshold to induce action potential
(E) open of the voltage-gated channels

23. Survivin is an apoptosis inhibitor in humans. If the survivin gene is mutated so that it produces too much of the survivin protein, which of the following would be the most likely effect on limb formation? (A) Mitosis of the limb bud cells would not occur. (B) Cells would not migrate to their correct position. (C) Cell determination would not occur. (D) Cell differentiation would not occur. (E) Webbing between digits would not be removed.

24. Primers are used in both PCR and in DNA sequencing. What is the purpose of the primers? (A) to separate the DNA template strands. (B) to provide a 3'- OH for DNA polymerase to build a new DNA strand. (C) to terminate synthesis of the growing DNA strand. (D) to separate various-sized DNA products. (E) to add nucleotides to a growing DNA strand.

25. If a plasmid lacks an origin of replication what will happen when it is transformed into bacteria? (A) As the bacteria divide they will lose the plasmid. (B) There will not be regions to clone genes into the plasmid. (C) Bacteria containing the plasmid will not be able to grow in the presence of antibiotics. (D) The plasmid will not be useful in producing a protein because it lacks an RNA polymerase binding site. (E) The plasmid cannot be cut with restriction enzymes.

26. Neurons contain ________ to receive signals, contain ________ to send out signals. (A) axons, dendrites (B) nucleus, axon (C) dendrites, axons (D) axon hillock, axon (E) axon, axon hillock

28. It is correct to say that neural transmission across mammalian synaptic clefts is the result of (A) neural impulses involving the flow of and across the cleft. (B) neural impulses traveling across the gap as electrical currents. (C) neural impulses causing the release of chemicals that diffuse across the cleft. (D) neural impulses traveling across the cleft in both directions. (E) the calcium within the axons and dendrites of nerves adjacent to a synapse acting as the neurotransmitter.

29. In the peripheral nervous system, groups of neuronal cell bodies that are clustered together to perform basic functions are known as (A) nuclei. (B) ganglia. (C) nerves. (D) spinal cords. (E) somata.

30. Damage to the cerebellum could result in (A) decreased ability to balance. (B) loss of hearing. (C) loss of vision. (D) loss of taste sensation. (E) diminished thermoreceptive sensation.

31. What would a scientist see when looking through a microscope at a piece of shoulder muscle? (A) striations with unbranched fibers (B) striations with branched fibers (C) no striations and unbranched fibers (D) no striations and branched fibers (E) The scientist would see none of the above features in shoulder muscle.

32. In muscle function at the sarcomere level, the formation of cross-bridges is regulated by the binding of ____ ions to ______. (A) calcium, troponin (B) calcium, tropomyosin (C)calcium, myosin (D) sodium, troponin (E) sodium, tropomyosin

33. Imagine a red blood cell leaving the right ventricle of your heart. To which chamber of the heart will that cell return first? (A) right atrium (B) right ventricle (C) left atrium (D) left ventricle (E) impossible to say from information given