Ignore the numbering and the ** signs.

**23.  Which of the following best defines the term allele?  B

A.  the location of a gene on a chromosome.
B.  a version of a gene that occupies a specific location on a single chromosome.
C.  a recognizable characteristic that is influenced by genes.
D.  a sequence of nucleotide pairs that code for a specific amino acid sequence.
E.  a sequence of nucleotide pairs in DNA that causes RNA polymerase to transcribe.

**24.  In garden peas, tall is dominant over short. If you have a tall garden pea plant and you want to know its genotype, you should cross it with a plant that is    B

A.  homozygous dominant.
B.  homozygous recessive.
C.  heterozygous.
D.  tall.
E.  of the same genotype.

**25.  Mendel’s Law of Independent Assortment refers to assortment between which of the following?   A

A.  homologous chromosomes
B.  gametes
C.  sister chromatids
D.  recombinants
E.  none of the above

**26.  If short pea plants are recessive to tall (t versus T), yellow seeds are recessive to green (g versus G), and wrinkled seeds are recessive to round seeds (r versus R), what are the possible gametes that can be produced from a short pea plant that makes a wrinkled yellow seed?   D

A.  ttrrgg
B.  TTRRGG
C.  TtRrGg
D.  trg
E.  TRG

**27.  In a typical Mendelian cross, the F1 generation   C

A.  showed the dominant phenotype in a ¾ ratio.
B.  showed the dominant phenotype in a ¼ ratio.
C.  showed the dominant phenotype always.
D.  showed the recessive phenotype always.
E.  showed the recessive phenotype in a ¼ ratio.

**28.  Two black guinea pigs were mated and over several years produced 29 black and 9 white offspring. The most likely genotypes for the parents are   D

A.  bb and bb.
B.  BB and BB.
C.  Bb and bb.
D.  Bb and Bb.
E.  BB and bb.

**29.  In snapdragons, flower color is controlled by  incomplete dominance. What will the phenotype of the offspring be if a homozygous white plant is crossed with a heterozygous pink plant?
                                                                                                                B
A.  all pink.
B.  50% pink and 50% white.
C.  all white.
D.  75% pink and 25% white.
E.  cannot be determined with the information given.
 

**30.  A couple has three children, all of whom have brown eyes and blonde hair. Both parents are homozygous for brown eyes (BB), but one is blonde (rr) and othe other is a redhead (Rr). Assuming that there is no unusual dominance relationships for either of these two genes and that the phenotypes are not influenced by more than one gene, what is the probability that the next child will be a brown-eyed redhead?   D

A.  1 in 16
B.  1 in 8
C.  1 in 4
D.  1 in 2
E.  1

**31.  What do all males inherit from their mothers?   A

A.  X chromosome.
B.  Y chromosome.
C.  genes for normal perception of color.
D.  both A and C are correct.
E.  both B and C are correct.

**32.  People who have red hair usually have freckles. This can best be explained by   A

A.  linkage.
B.  failure of sister chromatids to separate during meiosis.
C.  sex-influenced inheritance.
D.  independent assortment.
E.  incomplete dominance.
 
 

**34.  What are the possible genotypes for a color-blind male?   B

A.  XcXc only
B.  XcY only
C.  X+Yc only
D.  XcXc and XcY
E.  XcY and X+Yc

**35.  Incomplete dominance occurs when   B

A.  chromosomes are deleted.
B.  heterozygotes synthesize a variable amount of an enzyme.
C.  the genes fail to segregate.
D.  the law of independent assortment is upheld.
E.  one gene has multiple effects.

**36.  Segregation of alleles occurs   A

A.  during gamete formation.
B.  at fertilization.
C.  during mitosis.
D.  during the random combination of gametes to produce the F2 generation.
E.  only in a dihybrid cross.

**37.  If a color blind female marries a normal visioned male, their offspring should be   D

A.  50% color blind, 50% normal for both sexes.
B.  all color blind for both sexes.
C.  all normal males, all color blind females.
D.  all color blind males, all normal females.
E.  50% normal males, 50% color blind males, all normal females.

**38.  An offspring that has a combination of phenotypes that is not present in either of the parents of a cross is called a   C

A.  mutant.
B.  parental.
C.  recombinant.
D.  heterozygote.
E.  homozygote.

**39.  Why would you predict that half of the human babies born will be males and half females?
                                                                                                                            A
A.  Because of segregation of the X and Y chromosomes during male meiosis.
B.  Because of segregation of the X chromosomes during female meiosis.
C.  Because all eggs contain an X chromosome.
D.  Because only Y gametes are formed in males and only X in females.
E.  Because two X gametes can never combine.

**40.  Genetic linkage (not sex-linkage)  D

A.  measures how many genes are found on a chromosome.
B.  measures how many chromosomes are found within a species.
C.  measures how often a particular set of genes gets transcribed.
D.  measures the distance between genes on a chromosome.
E.  measures how many alleles exist for a gene in a species.

**42.  A pea plant with red flowers is test crossed and one half of the resulting progeny have red flowers, while the other half have white flowers. You know that the genotype of the test-crossed plant is   B

A.  RR.
B.  Rr.
C.  rr.
D.  either RR or Rr.
E.  Cannot tell from this.
 

4.  During Griffith’s experiment, DNA from the lethal R strain was taken up by the non-lethal S Strain. _____F

5.  During the Hershey-Chase experiment, the radioactive phosphorus was found in the bacterial cell pellet. ____T

6.  The Hershey-Chase experiment proved that DNA was the molecule that allowed new phage particles to form. ____T
 
 

The following is a list of terms that we discussed in class. They may or may not relate to one or more of the statements below. Choose the term that BEST fits the statement and write the letter that is next to it as your answer. Terms can be used more than once or not at all. If no term applies, write E as your answer.

A.  topoisomerase A. centromere A. histone
B.  peptidyl transferase B. chromatin B. DNA helicase
C.  DNA polymerase C. chromatid C. spindle
D.  DNA ligase  D. kinetochore D. protein kinase

1.  Holds sister chromatids together. _____OMIT
2.  Makes the messenger RNA. _____E
3.  Melts the hydrogen bonds that hold DNA strands together. _____B
4.  Part of the nucleosome. _____OMIT
5.  Connects Okazaki fragments. _____D
6.  Transfers phosphate groups between molecules. _____OMIT
7.  The exact copy of a chromosome following S phase. _____OMIT
8.  Attaches the amino acid to the tRNA. _____E
9.  Enzyme that operates during S phase. _____A,B,C, or D
10.  Prevents tangling of the DNA as the replication fork progresses. _____A
11.  Connects deoxynucleotides together. _____C
12.  DNA complexed with nucleosomes. _____OMIT
13.  Part of the ribosome. _____B
14.  Activated by binding to a cyclin. _____OMIT
15.  Attaches amino acids together. _____B
 

 True or False. If True, answer A, if False, answer B.

23.  DNA is made from nucleotides that do not have a OH group attached to carbon number 3 of the ribose. _____B
24.  Phosphodiester bonds are made between the 3’phosphate of one nucleotide and the 5’ OH of another. _____B
25.  B-DNA is a double-stranded molecule made up of two parallel polymers of DNA. _____B
 

Questions 26-50 are multiple choice. Select the BEST answer.
 
 

30.  The rules formulated by Chargaff that helped Watson and Crick work out the structure of DNA state that   A

A.  A=T and G=C in any molecule of DNA.
B.  A=C and G=T in any molecule of DNA.
C.  A=G and C=T in any molecule of DNA.
D.  A=U and G=C in any molecule of DNA.
E.  A=U and G=T in any molecule of DNA.

31.  During replication, the new DNA strand is synthesized   B

A.  in the 3’-5’ direction always.
B.  in the 5’-3’ direction always.
C.  in both the 3’-5’ direction and the 5’-3- direction from the replication fork.
D.  in either the 3’-5’ or 5’-3’ direction depending on the polarity of the template strand.
E.  always from one end of the DNA molecule to the other, regardless of the direction.

32.  Double-stranded DNA looks like a ladder that has been twisted into a spiral. The steps of the ladder are   B

A.  individual nitrogenous bases.
B.  pairs of bases.
C.  alternating bases and phosphate groups.
D.  alternating sugars and bases.
E.  alternating sugars and phosphate groups.

33.  If a double-stranded DNA molecule contains 30% T, how much G does it contain?  A

A.  20%
B.  30%
C.  40%
D.  50%
E.  Cannot answer with this amount of information.

34.  Which of the following statements about the flow of genetic information is correct?   D

A.  Proteins encode information that is used to produce other proteins of the same amino acid sequence.
B.  RNA encodes information that is transcribed into DNA, and DNA encodes information that is translated into proteins.
C.  Proteins encode information that can be translated into RNA, and RNA encodes information that can be transcribed into DNA.
D.  DNA encodes information that is transcribed into RNA, and RNA encodes information that is translated into proteins.
E.  DNA encodes information that is transcribed into proteins which are then translated into RNA.
 

35.  A sequence of RNA bases can function as a   E

A.  codon.
B.  anticodon.
C.  START signal.
D.  Both A and B are correct.
E.  All are correct.

36.  Transcription is the process of   C

A.  synthesizing a DNA molecule from an RNA template.
B.  assembling ribonucleotide triphosphates into an RNA molecule without a template.
C.  synthesizing an RNA molecule using a DNA template.
D.  synthesizing a protein using information from messenger RNA.
E.  replicating a single-stranded DNA molecule.

37.  During translation initiation, the first site occupied by a charged tRNA is   E

A.  the A site.
B.  the B site.
C.  the large subunit.
D.  the T site.
E.  the P site.

38.  During translation elongation but before translocation, the existing polypeptide chain is transferred to   A

A.  the tRNA occupying the A site.
B.  the tRNA occupying the P site.
C.  the ribosomal RNA.
D.  the peptidyl transferase.
E.  signal recognition particle.

39.  The region of a gene that binds RNA polymerase to initiate transcription is called   E

A.  the exon.
B.  the intron.
C.  the cap.
D.  the poly A tail.
E.  the promoter.
 
 

Use the following figure to answer questions 42 and 43.
 

This was a picture of a replication fork.
 
 
 

42.  Which strand will be replicated discontinuously using Okazaki fragments?

 A.
 B.

43.  Which strand will give rise to the leading strand?

 A.
 B.

44.  Eucaryotic mRNAs   A

A.  have a CAP attached at the 5’end.
B.  have a CAP attached at the 3’ end.
C.  have a poly-A tail attached at the 5’ end.
D.  both A and C are correct.
E.  both B and C are correct.

45.  Splicing   D

A.  Occurs during translation.
B.  removes exons from  DNA.
C.  Removes exons from RNA.
D.  Removes introns following transcription.
E.  None of the above is correct.

Use the following picture to answer questions 46 and 47.
 

This was a picture of a transfer RNA molecule
 
 
 

46.  Where is the amino acid attached?

 A.
 B.
 C.
 D.
 E.

47.  Where is the anticodon found?

 A.
 B.
 C.
 D.
 E.
 

48.  Which of the following is a possible codon-anticodon interaction?   B and E

A.  5’AUG3’ (codon) with 5’UAC3’ (anticodon)
B.  5’AUG3’ (codon) with 3’UAC5’ (anticodon)
C.  5’AUG3’ (codon) with 5’TAC3’ (anticodon)
D.  5’AUG3’ (codon) with 3’TAC5’ (anticodon)
E.  3’AUG5’ (codon) with 5’UAC3, (anticodon)

49.  If the sequence of bases in a mRNA molecule is 5’CAUGUA3’ then   B

A.  the sequence of the template strand was 5’GTACAT3’.
B.  the sequence of the template strand was 5’TACATG3’.
C.  the sequence of the template strand was 5’GUACAU3’.
D.  the sequence of the template strand was 5’UACAUG3’.
E.  the sequence of the template strand was 5’CATGTA3’ .