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.

19.Which of the following statements regarding the differences between mitosis and meiosis is false? (A) In meiosis four daughter cells are produced, whereas in mitosis two daughter cells are produced. (B) Cells produced by mitosis are normally diploid, whereas cells produced by meiosis are normally haploid. (C) In mitosis cytokinesis occurs once, whereas in meiosis cytokinesis occurs twice. (D) Crossing over is a phenomenon that happens only in meiosis. (E) In mitosis the chromosomes replicate only once, whereas in meiosis the chromosomes replicate twice.

20. Type 1 fucosidosis is a rare buman disease. Patients cannot hydrolyze the disaccharide fucose, and as a result have severe neurological decline and die by age 6. The disease is due to a defect in the gene that encodes the lysosomal enzyme that breaks down fucose (α-1-fucosidase), and is inherited in an autosomal recessive manner. Jane and John have a child who has Type 1 fucosidosis. What is the probability that their next two children will all NOT have the disease? (A) None (all of their children will have the disease) (B) 1/2 (C) 3/4 (D) 1/8 (E) 9/16

21. If the recombination frequency between gene A and B is 10 out of 100 offspring, gene A and C is 30 out of 100 offspring, and gene B and C is 40 out of 100 offspring, what is the location of these genes in relation to each other on a chromosome? (A) CAB (B) BAC (C) ABC (D) CBA (E) either CAB or BAC

22. Which of the following phrases INCORRECTLY finishes this statement? Stem cells (A) can undergo mitosis. (B) can differentiate into more than one type of specialized cell. (C) vary in their potency. (D) are only found in embryos. (E) can sometimes only differentiate into one cell type.

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

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

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.