Tuesday, September 30, 1997
                                   S. Shostak
                                  BioSci 0160
                                     EXAM 1

Instructions:
You know the drill: YOU MUST USE A #2 PENCIL ON YOUR ANSWER SHEET. PRINT YOUR
NAME, STUDENT NUMBER, AND FILL IN THE APPROPRIATE CIRCLES. Read each question
carefully before answering. Work at a steady pace, and you should have ample
time to finish. YOU MUST SHOW YOUR STUDENT ID WHEN DEPOSITING YOUR ANSWER
SHEET (in color coded pile) BEFORE LEAVING THE ROOM. You may keep the questions
and pick up an answer sheet (color coded for your particular set of questions).
                 _____________________________________________

 1. Which of the following organisms does not reproduce cells by
    mitosis and cytokinesis?
    a. cow
    b. bacterium
    c. mushroom
    d. cockroach
    e. banana tree

 2. If there are 12 chromosomes in an animal cell in G1 stage of the
    cell cycle, what is the diploid number of chromosomes for this
    organism?
    a. 6
    b. 12
    c. 24
    d. 36
    e. 48

 3. How do the daughter cells at the end of mitosis and cytokinesis
    compare with their parent cell when it was in G1 of the cell cycle?
    a. The daughter cells have half the amount of cytoplasm and half the
       amount of DNA.
    b. The daughter cells have half the number of chromosomes and half
       the amount of DNA.
    c. The daughter cells have the same number of chromosomes and half
       the amount of DNA.
    d. The daughter cells have the same number of chromosomes and the
       same amount of DNA.
    e. The daughter cells may have new combinations of genes due to
       crossing over.

 4. Measurements of the amount of DNA per nucleus were taken on a large
    number of cells from a growing fungus. The measured DNA levels
    ranged from 3 to 6 picograms per nucleus. One nucleus had 5
    picograms of DNA. What stage of the cell cycle was this nucleus in?
    a. G0
    b. G1
    c. S
    d. G2
    e. M

 5. Proteins that are involved in the regulation of the cell cycle, and
    that show fluctuations in concentration during the cell cycle, are
    called
    a. ATPases.
    b. kinetochores.
    c. centrioles.
    d. proton pumps.
    e. cyclins.

 6. A cell with 20 chromosomes (diploid number) goes through the cell
    cycle. The number of chromosomes after doubling the DNA in the S
    phase is
    a. 20.
    b. 40.
    c. 10.
    d. called the S number of chromosomes.
    e. called haploid.

 7. If the liver cells of an animal have 24 chromosomes, the sperm cells
    would have how many chromosomes?
    a. 12
    b. 24
    c. 48
    d. twice the diploid number
    e. half the haploid number

 8. What is a karyotype?
    a. the phenotype of an individual
    b. the genotype of an individual
    c. a unique combination of chromosomes found in a gamete
    d. the kind of nucleus a cell has
    e. a method of organizing the homologous chromosomes of a cell in
       relation to their number, size, and type

                 ---------------------------------------
    Use the key shown below to answer the following question(s). Each
    answer may be used once, more than once, or not at all.
 
         1. The statement is true for mitosis only.
         2. The statement is true for meiosis I only.
         3. The statement is true for meiosis II only.
         4. The statement is true for mitosis and meiosis I.
         5. The statement is true for mitosis and meiosis II.

 9. Homologous chromosomes synapse and crossing over occurs.
    a. 1
    b. 2
    c. 3
    d. 4
    e. 5

10. Centromeres uncouple and chromatids are separated from each
    other.
    a. 1
    b. 2
    c. 3
    d. 4
    e. 5

                 ---------------------------------------
    Refer to the life cycles illustrated in Figure 12.2  (not available)
 

11. Which of the life cycles is typical for animals?
    a. I only
    b. II only
    c. III only
    d. I and II
    e. I and III

12. Which of the life cycles is typical for plants and some algae?
    a. I only
    b. II only
    c. III only
    d. I and II
    e. I and III

13. A couple who are both carriers for the gene for cystic fibrosis have
    two children who have cystic fibrosis. What is the probability that
    their next child will have cystic fibrosis?
    a. 0%
    b. 25%
    c. 50%
    d. 75%
    e. 100%

14. A couple who are both carriers for the gene for cystic fibrosis have
    two children who have cystic fibrosis. What is the probability that
    their next child will be phenotypically normal?
    a. 0%
    b. 25%
    c. 50%
    d. 75%
    e. 100%

15. What is a genetic cross between an individual of unknown genotype
    and a homozygous recessive?
    a. a self-cross
    b. a testcross
    c. a hybrid cross
    d. an F1 cross
    e. a dihybrid cross

16. Which of the following is an example of polygenic inheritance?
    a. pink flowers in snapdragons
    b. the ABO blood groups in humans
    c. sex-linkage in humans
    d. white and purple color in sweet peas
    e. skin pigmentation in humans

17. A 9:3:3:1 phenotypic ratio is characteristic of the
    a. F1 generation of a monohybrid cross.
    b. F2 generation of a monohybrid cross.
    c. F1 generation of a dihybrid cross.
    d. F2 generation of a dihybrid cross.
    e. F2 generation of a trihybrid cross.

18. In a cross AaBbCc x AaBbCc, what is the probability of producing the
    genotype AABBCC?
    a. 1/4
    b. 1/8
    c. 1/16
    d. 1/32
    e. 1/64

19. The frequency of crossing over between any two linked genes is
    a. more likely if they are recessive.
    b. difficult to predict.
    c. determined by their relative dominance.
    d. the same as if they were not linked.
    e. proportional to the distance between them.

20. A recessive allele on the X chromosome is responsible for red-green
    color blindness in humans. A normal vision woman whose father is
    color-blind marries a color-blind male. What is the probability that
    this couple's son will be color-blind?
    a. 0%
    b. 25%
    c. 50%
    d. 75%
    e. 100%

21. A man who carries an X-linked allele will pass it on to
    a. all of his daughters.
    b. half of his daughters.
    c. all of his sons.
    d. half of his sons.
    e. all of his children.

                 ---------------------------------------
    The pedigree chart below (Figure 14.1) indicates the inheritance of
    color blindness (sex-linked). Answer the following question(s) using
    the key under the Figure.   (not available)
 

22. In the pedigree in Figure 14.1  (not available), what is the probability that
    individual III-1 is heterozygous?
    a. 0.25
    b. 0.33
    c. 0.50
    d. 0.66
    e. 0.75

23. In the pedigree in Figure 14.1, what is the probability that
    individual III-3 is homozygous?
    a. 0
    b. 0.25
    c. 0.5
    d. 0.75
    e. 1.0

24. If a pair of homologous chromosomes fails to separate during
    anaphase of meiosis I, what will be the chromosomes number (n) of
    the four resulting gametes?
    a. n+1; n+1; n-1; n-1
    b. n+1; n-1; n; n
    c. n+1; n-1; n-1; n-1
    d. n+1; n+1; n; n
    e. n-1; n-1; n; n

                 ---------------------------------------
    Refer to Figure 14.3 to answer the following question(s).  (not  available)
 
 

25. In a series of mapping experiments, the recombination frequency for
    four different linked genes of Drosophila were determined as shown
    above. What is the order of these genes on a chromosome map?
    a. rb-cn-vg-b
    b. vg-b-rb-cn
    c. cn-rb-b-vg
    d. b-rb-cn-vg
    e. vg-cn-b-rb

26. The problem of replicating the lagging strand��that is, adding bases
    in the 3'--> 5' direction��is solved by DNA through the use of
    a. base-pairing.
    b. replication forks.
    c. the unwinding enzyme, helicase.
    d. Okazaki fragments.
    e. topoisomerases.

27. What kind of chemical bonds are found between paired bases of the
    DNA double helix?
    a. hydrogen
    b. ionic
    c. covalent
    d. sulfhydryl
    e. phosphate

28. What is the primer that is required to initiate the synthesis of a
    new DNA strand?
    a. RNA
    b. DNA
    c. protein
    d. ligase
    e. primase

29. Which enzyme catalyzes the elongation of a DNA strand in the 5'-->
    3' direction?
    a. primase
    b. DNA ligase
    c. DNA polymerase
    d. topoisomerase
    e. helicase

30. Which of the following descriptions best fits the class of molecules
    known as nucleotides?
    a. a nitrogen base and a phosphate group only
    b. a nitrogen base and a five-carbon sugar only
    c. a nitrogen base, a phosphate group, and a five-carbon sugar
    d. a five-carbon sugar, a phosphate group, and a purine
    e. a pyrimidine, a purine, and a six-carbon sugar

31. Suppose one were provided with an actively dividing culture of E.
    coli bacteria to which radioactive thymine had been added. What
    would happen if a cell replicated once in the presence of this
    radioactive base?
    a. One of the daughter cells, but not the other, would have
       radioactive DNA.
    b. Neither of the two daughter cells would be radioactive.
    c. All four bases of the DNA would be radioactive.
    d. Radioactive thymine would pair with nonradioactive guanine.
    e. DNA in both daughter cells would be radioactive.

32. In an analysis of the nucleotide composition of DNA to see which
    bases are equivalent in concentration, which of the following would
    be true?
              1. A = C
              2. A = G and C = T
              3. A + C = G + T
              4. A + T = G + C
    a. 1
    b. 2
    c. 3
    d. 4
    e. Both 2 and 3 are true.

33. What is the relationship among DNA, a gene, and a chromosome?
    a. A chromosome contains hundreds of genes which are composed of
       protein.
    b. A chromosome contains hundreds of genes which are composed of
       DNA.
    c. A gene contains hundreds of chromosomes which are composed of
       protein.
    d. A gene is composed of DNA, but there is no relationship to a
       chromosome.
    e. A gene contains hundreds of chromosomes which are composed of
       DNA.

34. All of the following are directly involved in translation EXCEPT
    a. mRNA.
    b. tRNA.
    c. ribosomes.
    d. DNA.
    e. amino acid-activating enzymes.

35. RNA differs from DNA in that RNA
         1. contains ribose as its sugar.
         2. is found only in cytoplasm.
         3. contains uracil instead of thymine.
    a. 1
    b. 2
    c. 3
    d. 1 and 3 are correct.
    e. 1, 2, and 3 are correct.

36. From the following list, which is the first event in translation in
    eukaryotes?
         1. elongation of the polypeptide
         2. base pairing of activated methionine-tRNA to AUG of the
            messenger
         3. binding of the larger ribosomal subunit to smaller ribosome
            subunits
         4. covalent bonding between the first two amino acids
    a. 1
    b. 2
    c. 3
    d. 4
    e. Both 2 and 4 occur simultaneously.

37. As a ribosome translocates along an mRNA molecule by one codon,
    which of the following occurs?
         1. The transfer RNA that was in the A site moves into
            the P site.
         2. The tRNA that was in the P site moves into the A site.
         3. The tRNA that was in the P site departs from the ribosome.
         4. The tRNA that was in the A site departs from the ribosome.
    a. 1
    b. 2
    c. 3
    d. 4
    e. Both 1 and 3 are correct.

38. Which point mutation would be most likely to have a catastrophic
    effect on the functioning of a protein?
    a. a base substitution
    b. a base deletion near the start of the coding sequence
    c. a base deletion near the end of the coding sequence, but not in
       the terminator codon
    d. deletion of three bases near the start of the coding sequence,
       but not in the initiator codon
    e. a base insertion near the end of the coding sequence, but not in
       the terminator codon

                 ---------------------------------------
    Refer to Figure 16.1 to answer the following question(s).  (not available)
 

39. What amino acid sequence will be generated, based on the following
    mRNA codon sequence?   5' AUG-UCU-UCG-UUA-UCC-UUG
    a. met-arg-glu-arg-glu-agr
    b. met-glu-arg-arg-gln-leu
    c. met-ser-leu-ser-leu-ser
    d. met-ser-ser-leu-ser-leu
    e. met-leu-phe-arg-glu-glu

40. Suppose the following DNA sequence was mutated from
    AGAGAGAGAGAGAGAGAGA to AGAAGAGAGATCGAGAGA. What amino acid sequence
    will be generated based on this mutated DNA?
    a. arg-glu-arg-glu-agr-glu
    b. glu-arg-glu-leu-leu-leu
    c. ser-leu-ser-leu-ser-leu
    d. ser-ser-leu
    e. leu-phe-arg-glu-glu-glu

                 ---------------------------------------
    Each of the following is a modification of the sentence
    THECATATETHERAT.
               1. THERATATETHECAT
               2. THETACATETHERAT
               3. THECATARETHERAT
               4. THECATATTHERAT
               5. CATATETHERAT

41. Which of the above is analogous to a frameshift mutation?
    a. 1
    b. 2
    c. 3
    d. 4
    e. 5

42. Which of the above is analogous to a single substitution mutation?
    a. 1
    b. 2
    c. 3
    d. 4
    e. 5

43. The function of reverse transcriptase in retroviruses is to
    a. hydrolyze the host cell's DNA.
    b. use viral RNA as a template for DNA synthesis.
    c. convert host cell RNA into viral DNA.
    d. translate viral RNA into proteins.
    e. use viral RNA as a template for making complementary RNA strands.

44. Bacteriophages that have become integrated into the host cell
    chromosome are called
    a. intemperate bacteriophages.
    b. transposons.
    c. prophages.
    d. T-even bacteriophages.
    e. plasmids.

                 ---------------------------------------
    Answer the question(s) by matching the following terms with the
    appropriate phrase or description below. Each term can be used once,
    more than once, or not at all.
 
              1. operon
              2. operator
              3. promoter
              4. repressor
              5. corepressor

45. A protein that is produced by a regulatory gene.
    a. 1
    b. 2
    c. 3
    d. 4
    e. 5

46. The binding of an active repressor molecule at this site prevents
    the binding of RNA polymerase.
    a. 1
    b. 2
    c. 3
    d. 4
    e. 5

47. You would expect the lactose operon to be transcribed when
         1. there is more glucose in the cell than lactose.
         2. there is more lactose in the cell than glucose.
         3. there is lactose but no glucose in the cell.
         4. the cyclic AMP levels are high within the cell.
    a. 1
    b. 2
    c. 3
    d. 4
    e. Both 3 and 4 are correct.

                 ---------------------------------------
    Use the choices shown below to answer the following question(s).
    The choices may be used once, more than once, or not at all.
 
              1. transduction
              2. transposition
              3. translation
              4. transformation
              5. conjugation

48. DNA is transferred from one bacterium to another by a virus.
    a. 1
    b. 2
    c. 3
    d. 4
    e. 5

49. DNA from one strain of bacteria is assimilated by another strain.
    a. 1
    b. 2
    c. 3
    d. 4
    e. 5

50. Which of the following does NOT consist of a sequence of bases?
    a. repressor
    b. structural gene
    c. promoter
    d. regulator gene
    e. operator