Multiple Choice: Circle the best answer.

1. The antiparallel nature of DNA is best explained by which of
       the  following?
     a. The two strands run in opposite directions, each has an
        exposed 5' phosphate on one end and exposed 3'hydroxyl group on the other.
     b. The two strands run in the same direction, making it a simple
          matter to copy an identical but antiparallel strand of RNA.
     c. The bases are antiparallel to the long axis of the molecule.
     d. Both a and c are true.
     e. None of the above are true.

2. Which of the following is the best definition of semiconservative
     replication?
     a. The translation of a DNA molecule into a complementary
         strand of RNA.
     b. The fact that a DNA molecule consists of one parental strand and one new strand.
     c. The fact that the number of DNA molecules is doubled with
         every other replication.
     d. Both a and b are true.
     e. None of the above are true.

3. Which of the following adds nucleotides to a growing
     polynucleotide chain of DNA?
     a. DNA polymerase
     b. DNA helicase enzyme
     c. RNA primer
     d. RNA polymerase
     e. None of the above

4. Which of the following cause the unwinding of the double helix?
     a. DNA polymerase
     b. DNA helicase enzyme
     c. RNA primer
     d. RNA polymerase
     e. None of the above

5. Which of the following is the best definition of an RNA primer:
     a. An RNA primer is a short piece of RNA that initiates DNA synthesis once the two strands are separated.
     b. An RNA primer provides an initiation site for the first several
          nucleotides in the newly forming DNA molecule.
     c. An RNA primer moves the two DNA strands apart so that
         formation of daughter DNA strands can begin.
     d. Both a and b are true.
     e. Both a and c are true.

6. In DNA replication, the lagging strand
     a. is synthesized as a series of Okazaki  fragments
     b. is synthesized as a complementary copy of  the leading strand
     c. pairs with the leading strand by  complementary base pairing
     d. is made up entirely of RNA primers
     e. is not synthesized until the synthesis of  the leading strand is
         completed

7. Nucleosomes are best described as:
     a. eukaryotic DNA associated with histone proteins.
     b. prokaryotic DNA associated with nonhistone proteins.
     c. eukaryotic DNA associated with nonhistone proteins.
     d. prokaryotic DNA associated with histone proteins.
     e. None of the above.

8. One of the codons specifying the amino acid leucine is
      5'-CUA-3'.  Its corresponding anticodon is
     a. 5'-CUA-3'
     b. 3'-AUC-5'
     c. 3'-GAU-5'
     d. 3'-GAT-5'
     e. 5'-GAU-3'

9. Uracil forms a complementary pair with
     ________ in RNA and ________ in DNA.
     a. adenine, adenine
     b. adenine, thymine
     c. thymine, thymine
     d. uracil, adenine
     e. adenine, uracil

10. Anticodons are:
     a. part of the tRNA molecule.
     b. produced on all DNA templates.
     c. made of three bases.
     d. Only found in prokaryotic cells.
     e. Only a and c are true

11. During protein synthesis, ribosomes:
      a. attach to the mRNA molecule and travel along its length.
      b. attach to the DNA molecule and travel along its length to
           produce an mRNA molecule.
      c. translate mRNA to tRNA.
      d. transcribe mRNA to tRNA.
      e. Both a and d are true.

12. Why is only one strand of DNA transcribed  into mRNA?
      a. Because mRNA is only required in small quantities.
      b. Transcribing both DNA strands would produce different
           amino acid sequences.
      c. Only one strand of DNA contains the correct sequence of
           nucleotides.
      d. Both a and b are true.
      e. Both b and c are true.

13. Aminoacyl-tRNA synthetases function to:
      a. initiate the formation of prptide bonds between amino acids.
      b. covalently link amino acids to their respective tRNA
          molecules.
      c. break the bond between amino acids and  tRNAs so that the
          amino acid can join the growing polypeptide chain.
      d.Both a and c are true.
      e. None of the above are true.

14. The transcribed DNA sequence that is
      complementary to the codon 5'-CUA-3' is
      a. 5'-CUA-3'
      b. 3'-AUC-5'
      c. 3'-GAU-5'
      d. 3'-GAT-5'
      e. 5'-GAU-3'

15. The principle of dominance states that:
     a. the dominant trait shows up at least 50% of the time in the first
         generation.
     b. the F₁ generation of a hybrid cross always   exhibit dominant
         traits.
     c. one gene can mask the expression of another in a hybrid.
     d. all of the above are true.
     e. none of the above are true.

16. The principle of segregation states that:
     a. the separation of a species into two populations is the main
         mechanism of speciation.
     b. the genes of a pair separate before gametes are formed.
     c. dominant genes always remain paired during gamete formation
         while recessive genes separate.
     d. both a and b are true.
     e. both a nd c are true.

17. _________ are genes that govern the same feature, such as eye
      color, and occupy corresponding positions on homologous
      chromosomes.
     a. alleles
     b. loci
     c. homozygotes
     d. coupled traits
     e. none of the above

18. Which of the following represent the possible genotypes
       resulting from a cross between an individual homozygous for
       black hair (BB) and an individual heterozygous for black hair
       (Bb)?
      a. BB and Bb
      b. BB, Bb and bb
      c. BB only
      d. Bb only
      e. bb only

19. What is the probability that two lizards that are heterozygous for
       stripes on their tails (Ss) will produce an offspring that is
      homozygous for no stripes (ss)?
      a. They will always produce offspring that are
          homozygous for no stripes.
      b. The probability is 1/2 that they will produce offspring
           homozygous for no stripes.
      c. The probability is 1/4 that they will produce offspring
           homozygous for no stripes.
      d. The probability is 1/8 that they will produce offspring
           homozygous for no stripes.
      e. They will never produce offspring homozygous for no stripes.

20. Two Martians fall in love and get married. One Martian is
       homozygous for red eyes (RR) while the other is heterozygous
       for red eyes (Rr). The recessive eye color is purple. What
      are the chances that they will have a child with purple eyes?
      a. 1/1
      b. 1/2
      c. 1/4
      d. 3/4
      e. 0

21. Why is color-blindness more common in males than in females?
      a. because females would have to receive two copies of the
          recessive color blindness gene to actually express the trait.
      b. because a male only need receive the recessive gene from his
          mother to be color-blind.
      c. because color-blindness is an X-linked trait.
      d. all of the above.
      e. none of the above.

22. Why is pattern baldness more common in men than in women?
      a. the gene may be influenced by the presence of sex hormones.
      b. because of the effect of genes on the Y chromosome.
      c. because females would need to be homozygous for the trait
          to express pattern baldness.
      d. both a and b are true.
      e. both a and c are true.

23. __________ refers to a situation in which several pairs of
      alleles  interact to affect a single trait.
      a. variegation
      b. codominance
      c. incomplete dominance
      d. epistasis
      e. none of the above

24. _______________ refers to multiple independent pairs of
      genes having similar and additive effects on the same
      characteristic.
      a. Codominance
      b. Epistasis
      c. Polygenic inheritance
      d. Complete dominance
      e. Additive dominance

Essay. Answer each question in the space
provided. The value of each question is indicated
in parenthesis.

1. Below is an ear of corn with purple (dominant)
    and yellow (recessive) kernels. Answer the
    following questions regarding this ear of corn.
    (6 pts)
    a. Would this represent the F₁ generation of a
         monohybrid cross, the F₂ generation of a
         monohybrid cross, or is this a result of a
         test cross? Explain.

     b. What would be the possible genotype(s) of
         the purple kernels? Explain.

2. In snapdragons, tallness (T) is dominant to
    dwarfness (t), and red flower color is due to
    gene (R) and white is its allele (r). The
    heterozygous (Rr) condition results in pink
    flower color. A dwarf white snapdragon is
    crossed with a plant homozygous for tallness
    and white flowers. What are the gneotypes
    and phenotypes and genotypic and phenotypic
    ratios of the F2 individuals? (6 pt)

3. True or False? Semiconservative replication of
    DNA means that DNA synthesis must be
    primed using an RNA molecule.Explain.