GENETICS - BIOL 7    EXAM I - September 19, 2002    NAME:

DO NOT USE ANY OTHER PAPER AT ANY TIME WITHOUT INSTRUCTOR PERMISSION

Part I: [42 points]  Choose the one BEST answer.  Circle its letter. Read each question and all 5 choices carefully because more than one answer might seem correct at first glance.  1.5  points each

1.  A specific site on a chromosome is a
    a.  marker
    b.  locus
    c.  gene
    d.  allele
    e.  homolog

2.  Given a cross between AAQqttGgbbDd x AaQqTtGgbbDd what is the chance of an offspring expressing the dominant trait for all of these loci?
    a.  0
    b.  1/4
    c.  1/6
    d.  1/64
    e.  1/512

3.  In peas, dwarf is a recessive phenotype.  What is the probability of dwarf progeny in the F2 of a monohybrid cross (assuming homozygosity in P)
    a.  0%
    b.  100%
    c.  ½
    d.  1/4
    e.  1/8

4.  In peas, dwarf is a recessive phenotype.  What is the probability of dwarf progeny in the F1 of a monohybrid cross (assuming homozygosity in P)
    a.  0%
    b.  100%
    c.  ½
    d.  1/4
    e.  1/8

5.  Given a cross between AaQqTtGgbbDd x AaqqTtggBbDd what is the chance of an offspring homozygous recessive at all of these loci?
    a.  0
    b.  1/4
    c.  1/6
    d.  1/64
    e.  1/512

6.  A cross between an individual whose genotype may or may not be known and an individual homozygous recessive at all alleles under study is a
    a.  backcross
    b.  testcross
    c.  reciprocal cross
    d.  cross over
    e.  cross not usually done on purpose, because it would not give useful information

7. A DNA molecule is made up of 20.62% guanine.  How much cytosine will it contain?
    a.  10.31%
    b.  41.24%
    c.  79.38%
    d.  20.62%
    e.  not enough information given
    f.  none of the above

8.  When two genes are on different chromosomes, we use independent event probability analysis (4 x 4 Punnett square) for dihybrid crosses because
    a.  our sample size will be small enough that errors will not matter much
    b.  Dr.  Schmeidler said it is a good method for this class
    c.  the sum law works well most of the time
    d.  the product law works gives the best results
    e.  the chromosomes assort independently during meiosis

9.  The cause of variation in the genome, and the cause of alleles is
    a.  epigenesis
    b.  polymorphism
    c.  mutation
    d.  meiosis
    e.  crossing over; recombination

10.  The term "wild type" indicates
    a.  organisms found outside captivity
    b.  organisms out of control
    c.  organisms particularly prone to mutate
    d.  the accepted "standard" strain of an organism, or allele of a gene (genotype or phenotype)
    e.  organisms which breed true

11.  The entire set of genetic information in an organism is called its
    a.  chromosome
    b.  genotype
    c.  genome
    d.  DNA
    e.  chromatin

12.  A gene determines an individual's potential to develop a particular phenotype;  This may be affected by
    a.  other genes
    b.  environment
    c.  evolution
    d.  a and b
    e.  all of the above

13.  The progeny of a monohybrid cross expressed a 3:1 phenotypic ratio.  This implies that
    a.  one parent was homozygous dominant and the other was homozygous recessive
    b.  one parent was heterozygous and the other was homozygous recessive
    c.  one parent was homozygous dominant and the other was heterozygous
    d.  both parents were heterozygous
    e.  none of the above is clear cut – several possibilities are valid

14.  Nucleotides in nucleic acids are held together by
    a.  covalent bonds
    b.  hydrogen bonds
    c.  ionic bonds
    d.  a and b
    e.  all of the above

15.  One DNA strand serves as a template for the synthesis of a complementary RNA strand during
    a.  replication
    b.  transcription
    c.  translation
    d.  all of the above
    e.  none of the above; this does not occur

16.  Which of the following are NOT correct base pairs in nucleic acids?
    a.  A-T
    b.  T-A
    c.  C- G
    d.  A-U
    e.  all of the above are correct base pairs

17.  Which of the following are diploid?
    a.  plants
    b.  animals
    c.  bacteria
    d.  most multicellular plants and animals, for at least part of their life cycle
    e.  all organisms, for at least part of their life cycle

18.  A region of DNA capable of being transcribed into a functional RNA product (mRNA or some other form) is
    a.  a gene
    b.  a protein
    c.  a polypeptide
    d.  mRNA
    e.  there is no one name that includes regions transcribed to mRNA and those transcribed to other RNAs
19.  A description of an individual's alleles is called its
    a.  phenotype
    b.  genotype
    c.  DNA
    d.  RNA
    e.  genome

20.  Norm of reaction is
    a.  a description of how phenotype changes with environmental change, for a given genotype
    b.  the normal range of phenotypes for an organism, before a phenotype is considered “mutant”
    c.  an explanation of how a gene's activity is affected by its environment
    d.  a graph of all the known variants in a population
    e.  a statistical analysis of genetic variation

21.  Base pairs in nucleic acids are held together by
    a.  covalent bonds
    b.  hydrogen bonds
    c.  ionic bonds
    d.  a and b
    e.  all of the above

22.  DNA differs from RNA in that
    a.  DNA contains 2'-deoxyribose while RNA contains ribose
    b.  RNA is usually single stranded while DNA is usually double-stranded
    c.  DNA is much more stable under all circumstances than is RNA
    d.  a and b
    e.  all of the above

23.  When an allele is expressed when present in a genome, that allele is called
    a.  recessive
    b.  dominant
    c.  an example of the "doctrine of use and disuse"
    d.  epigenesis
    e.  wild type

24.  A chromosome is made of
    a.  one piece of DNA with associated protein (and RNA)
    b.  euchromatin and heterochromatin
    c.  chromatin
    d.  a and b
    e.  all of the above

25.  Base pairing can occur
    a.  between DNA and DNA
    b.  between DNA and RNA
    c.  between DNA and protein
    d.  a and b
    e.  all of the above

26.  Gene activity must be regulated because
    a.  different cells require different products
    b.  all cells in an organism carry the same genes but may do different jobs
    c.  genes activity must be able to vary as the environment changes
    d.  a and b
    e.  all of the above

27.  An organism with a diploid chromosome number = 18 could generate      different gametes, (assuming no crossing over, recombination, or mutation) and      different possible offspring
    a.  18^2 ; 18^4
    b.  9^2 ; 9^2 x 9^2
    c.  21^8 ; 23^6
    d.  2^9 ; 2^9 x 2^9
    e.  2^9 ; 2^9 + 2^9

28.  Genes on the same chromosome are
    a.  independent
    b.  linked
    c.  coupled
    d.  homologous
    e.  alleles
Part II: [18 points]  omit two   Define, explain, and/or illustrate each of the following terms: be sure that you have both explained the meaning of each of the terms and distinguished each from other terms in the group.  For word pairs, explain the similarity and the distinction.  3 points each

a.  gene  -  allele

b.  chromatin  - chromosome

c.  genetic drift - natural selection

d.  pure line  -  breed true

e.  monohybrid cross  - dihybrid cross

f.  homozygous  – heterozygous

g.  nitrogenous base - nucleoside - nucleotide

h.  purine - pyrimidine

III. [40 points] Answer each question completely and clearly.  10 points each

1.        a.  DNA and RNA structure are similar in several ways.  Choose one similarity which is very important for the functions of DNA and RNA in a cell.  Explain the similarity and why it is so important for their functions.


        b.  DNA and RNA structure are different in several ways.  Choose one difference which is very important for the functions of DNA and RNA in a cell.  Explain the difference and why it is so important for their distinctive functions



2.   For each of the following, draw the simplest possible Punnett square which completely demonstrates all the possible outcomes, and write out the proportions of outcome genotypes and phenotypes:

                                                            phenotypes                    genotypes

                      DD x dd

                      Gg x gg

                       AaBb x aabb

                       EeQq x EeQq

                       Rg/rG x RG/rg

3.  What is the probability of  (always assuming no cheating or "unfair" circumstances): [put actual answer on the line; show work for possible partial credit]
      a.  tossing two coins at the same time and getting one heads and one tails?
      b.  tossing two coins at the same time and getting both tails?
      c.  throwing two dice,  and getting a 6 on one & a 4 or 5 on the other
      d.  one recessive and one dominant phenotype in the F2 of a dihybrid cross (assume P are homozygous)
      e.  dominant phenotype in the F2 of a monohybrid cross (assume P are homozygous)
      f.  tossing two dice and getting a sum of 8
      g.  the person to your right being female [ if you are in the seat the furthest to the right, use "the person to your left" ]

4.  Fill in the following table.  Show your work for possible partial credit; if you choose to do this, be sure that your work is legible and labeled sufficiently clearly to be understood by someone other than yourself.
 
 AaBb x AaBb AB/ab x Ab/aB Ab/aB  x Ab/aB
AB/ab x AB/ab
genotypes
















































phenotypes    
























 
bonus: Write a question that you studied for, and forgetful me, I neglected to ask.  Answer your question.  PLEASE ask yourself something you can answer well!  PLEASE answer the question you actually ask.  [up to 5 points awarded based on question & answer]