MOCK EXAM 3
1. In a test cross between a homozygous recessive white flower and an unknown purple flower, the cross results in ½ white flowers and ½ purple flowers. What is the genotype of the unknown purple flower?
A. Homozygous dominant
B. Heterozygous
C. Homozygous recessive
D. None of the above
2. A cross between two heterozygous purple flowers results in a ______genotype and a ______phenotype.
A. 1:2:1, 3:4
B. 2:3, 1:4
C. 1:2:1, 3:1
D. 2:1:2, 1:4
3. A true breeding parental crosses result in ______F1 offspring.
A. Heterozygous
B. Homozygous Dominant
C. Homozygous recessive
D. None of the above
4. A di-hybrid cross between 2 yellow round pea plants heterozygous for both seed shape and seed color result in a ______phenotypic ratio?
A. 9:3:4
B. 3:1
C. 9:3:3:1
D. 1:2:1
5. A botanist breeds a red flower with a white flower and observes that their offspring are white, red, and pink. What sort of dominance does this plant display?
A. Complete dominance
B. Codominance- Blood type AB, equal sharing of phenotype or trait, the flower would be both red and white
C. Incomplete Dominance- Blending of traits = pink, not equal sharing
D. Blending Hypothesis
6. Two Black Labs with the genotype BbEe are mated together. What is the chance that they have a puppy that has a yellow coat?
A. 9/16
B. 3/16
C. 1/4
D. Not a possible coat color
7. Neither Susie nor Joe have phenylketonuria, but each of their mothers has the disease. If Susie and Joe have three children, what is the probability that all three will be normal?
a. 1/16
b. 1/4
c. 3/4
d. 9/16
e. 27/64
8.Two genes in Drosophila, one controlling for eye color and the other for leg size, are located 10 map units apart on the same chromosome. Sepia eye color is dominant over blue eye color, and long legs are dominant over short legs. A true breeding fly with sepia eyes and long legs is crossed with a fly with blue eyes and short legs. The resulting F1 progeny are crossed with a fly that has blue eyes and short legs. If there are 1000 offspring obtained in the F2 generation, how many offspring would you expect for each phenotype?
a. 400 sepia eyes and long legs, 400 blue eyes and short legs, 100 sepia eyes and short legs, 100 blue eyes and long legs
b. 450 sepia eyes and long legs, 450 blue eyes and short legs, 50 sepia eyes and short legs, 50 blue eyes and long legs
c. 400 sepia eyes and long legs, 100 blue eyes and short legs, 400 sepia eyes and short legs, 100 blue eyes and long legs
d. 450 sepia eyes and long legs, 50 blue eyes and short legs, 450 sepia eyes and short legs, 50 blue eyes and long legs
e. 250 sepia eyes and long legs, 250 blue eyes and short legs, 250 sepia eyes and short legs, 250 blue eyes and long legs
9. Modifiers that control the color of the eye affect ______.
A. Amount of pigment
B. Tone of pigment
C. Where pigment is deposited
D. All of the above
10. John and Katy each have a sibling with Thalassemia, but neither John nor Katy nor any of their parents have the disease. Calculate the probability that if this couple has a child, the child will have Thalassemia.
A. 1/8
B. 1/4
C. 1/9
D. 2/3
11. Using the previous question’s information, what would the probability be if a test revealed that John is a carrier and Katy is not?
A. 1/4
B. 0
C. 2/3
D. 1/9
13. Newly discovered recessively inherited disease is expressed only in individuals with type O blood, although the disease and blood groups are independently inherited. A normal man with type A blood and a normal woman with type B blood have already had a child with the disease. The woman is now pregnant for a second time. What is the probability that the second child will also have the disease? Assume that both parents are heterozygous for the gene causing the disease.
A. 1/8
B. 1/4
C. 1/32
D.1/16
14. Which of the following diseases is least likely to be caused by nondisjunction during gametogenesis?
a. cri di chat
b. Turner’s syndrome
c. Klinefelter’s syndrome
d. triple X syndrome
e. Down syndrome
15. If a male that has Agammaglobulinmia mates with a female that is a carrier for the same disease, what percentage of their offspring will potentially be carriers?
A. 25%
B. 50%
C. 75%
D. 100%
For questions 16-18, choose from the following answer choices. Each may be used once, more than once, or not at all.
A. Topoisomerase
B. DNA polymerase
C. Helicase
D. primase
E. ligase
16. reduces strain on coiled part of DNA
17. unwinds double helix at replication forks
18. removes RNA primers
20. A male with ______could be confused with a woman if a scientist looked at a tissue sample.
A. Turner’s Syndrome
B. Triple X
C. XYY
D.Kleinfelter’s Syndrome
21. A di-hybrid grey-bodied normal wing female fly is crossed with a double mutant black body vestigial wing male. The cross yielded,: 30 gray normal, 4 black normal, 40 black-vestigial, and 26 grey vestigial. How many map units are the genes for body color and wing type located from each other?
A. 70 MU
B. 40 MU
C. 30 MU
D. unable to tell from information
22. In a cross between a yellow round pea plant with the genome YyRr and a green wrinkled pea plant with the genome yyrr, what phenotypes represent the recombinants of the cross?
A. Yellow round
B. green round
C. green wrinkled
D. Yellow wrinkled
E. Both B and D
23. Nondisjunction during meiosis 2 results in ______.
A. 2 triploid cells and 2 monosomiccells gametes
B. 2 monosomic cells and 2 diploid cells gametes
C.one triploid one monosomic and 2 diploid gametes
D. the shutdown of meiosis
24. Is non-disjunction in Meiosis 1 or 2 more dangerous (per say)?
A. Meiosis 1
B. Meiosis 2
C. Mathematically they are equally as dangerous as each other
D. Not enough is known about nondisjunction
25. In which genomic sequence is an inversion present:ABCDE
A.ACDEB
B.ACDE
C.AABCDE
D.ADCBE
27. By convention, each map unit corresponds to 1% recombination frequency. T or F
28. You are a geneticist, and you have just discovered yet another genetic disease. You observe the following: the disease is inherited only from the mother, it can be passed to both sons and daughters, and it causes abnormalities in the functioning of the citric acid cycle. Which of the following is the most likely explanation for the inheritance of the disease?
a. the disease is sex-linked and recessive
b. the disease is autosomal recessive
c. the gene that causes the disease is located on mitochondrial DNA
d. the disease is caused by the effects of genomic imprinting
e. the disease is caused by a reciprocal translocation
29. What is the percentage of Thymine in a DNA backbone if you know: Adenine = 30.3%, Guanine = 19.5%, and Cytosine = 19.5%.
A. 19.5%
B. 27.7%
C. 30.3%
D. 19.3 %
30. The Hershey chase experiment proved that DNA was the genetic material found in living organisms because radiolabeled 35-S was found inside the bacterial cells. T or F
31. A certain chemical is added to a eukaryotic cell during DNA replication that significantly reduces the speed of the replication in the lagging strand, but not the leading strand. Which of the following would be the most likely explanation?
a. the chemical inhibits topoisomerase, thereby causing increased stressed at the replication fork
b. the chemical prevent primases from laying down RNA primers quickly
c. the chemical prevents DNA polymerase from adding nucleotides
d. the chemical disrupts the normal functioning of helicase
e. the chemical causes DNA polymerase to run in the wrong direction
32. Which of the following types of RNA is incorrectly paired with its function?
a. mRNA- carries transcript of DNA
b. rRNA- composes the subunits of ribosomes
c. snRNA- catalyzes the addition of the poly-A tail
d. tRNA- transports amino acids to ribosome
e. tRNA- has anticodons complementary to mRNA
33. Which of the following is not true of RNA processing?
A. exons are cut out before mRNA leaves the nucleus
B. Nucleotides may be added at both ends of the RNA
C. Ribozymes may function in RNA splicing
D. RNA splicing can be catalyzed by splisosomes
E. A primary transcript is often much longer than the final RNA molecule that leaves the nucleus
34. If 5’-GTTTTAGTTAGCCATCTG-3’ is an entire transcription unit of DNA, determine the sequence of amino acids that would be transcribed. (Use the table at the end of the exam.)
a. Gln-Met-Ala-Asn-Asn
b. Gln-Asn-Gln-Ser-Val-Asp
c. Met-Leu-Val-Ser-His-Leu
d. Met-Ala-Asn-Asn
e. Met-Ala-Asn
35. The anticodon of a particular tRNA molecule is
A. complementary to the corresponding mRNA codon
B. complementary to the corresponding rRNA codon
C. the part of the tRNA that bonds to a specific amino acid
D. changeable depending on the AA that attatches to the tRNA
E. catalytic, making the tRNA a ribozyme
36. Which component is NOT directly involved in translation?
A. mRNA
B. DNA
C.tRNA
D. ribosomes
E. GTP
37. In a nucleosome, the DNA is wrapped around
A. polymerase
B. ribosomes
C. histones
D. thymine dimer
E.satelite DNA
38. The repressor protein in an operon system is made by the ______.
A. RNA Polymerase
B. functional genes
C. regulatory genes
D. promoter region
39. In a trp operon system, if excess intracellular tryptophan is high it will bind to the repressor causing the repressor to become ______.
A. activated
B. inactivated
C. bound to the operator
D. unbound from the operator
E. Both A and C
F. Both B and D
40. In the lac operon, bacteria make their repressors in the ______form
A. inactive
B. unprocessed
C. active
D. depends on if lactose is present
41. In the lac operon, ______binds to CAP. CAP then binds to ______.
A.cAMP, lactose
B. lactose, cAMP
C. lactose, the promoter region
D.cAMP, the promoter region
42. Regulatory genes are found ______the promoter region in an operon system.
A. before (upstream)
B. within
C. after (downstream)
D. all of the above
43. Which of the following matings cannot produce a child with the blood type O? The letter refers to the blood types (phenotypes).
A. O x O
B. O x AB
C. A x A
D. A x B
E. All of the above could produce a child with the blood type O.
44. The pedigree for a particular family is shown below.
Is the trait recessive or dominant? Is the mother of the first generation homozygous or heterozygous?
A. recessive/ homozygous
B.recessive heterozygous these are the possibilities, cant determine between the two
C. dominant/ homozygous
D. dominant/ heterozygous
E. There is not enough information available to answer the question.
45.Which of the following sets of nitrogenous base compositions for a strand of DNA is possible?
a. 20% thymine, 30% cytosine, 20% guanine, 30% adenine
b. 20% uracil, 20% cytosine, 20% guanine, 20% adenine, 20% thymine
c. 21% uracil , 29% cytosine, 29% guanine, 21% adenine
d. 22% thymine, 22% cytosine, 28% guanine, 28% adenine
e. 24% thymine, 26% cytosine, 26% guanine, 24% adenine
46. Unlike DNA polymerase, RNA polymerase
a. works in the 5’ to 3’ direction
b. attaches thymine to adenine bases
c. produces Okazaki fragments in the lagging strand
d. does not require a primer
e. requires helicase to pry DNA strands apart
47. Which of the following enzyme is not correctly paired with its function?
A. Single-strand proteins-keep separated strands of DNA from reconnecting
B. Topoisomerase- helps to relieve the strain off of the rest of the strand of DNA
C. Helicases- rewind the double helix after replication
D. Primase- synthesizes a small RNA segment called a primer
E. All of the above are paired correctly.
48. DNA polymerase adds nucleotides to the ______of the leading strands and to the ______of the lagging strands.
A. 5’ end….. 5’ end
B. 5’ end…… 3’ end
C. 3’ end…… 5’ end
D. 3’ end…… 3’ end
E. sugar group….. Phosphate group
49. Two genes that have a 50% recombination frequency
a. are located on different pairs of homologous chromosomes
b. are located right next to each other on the same chromosome
c. are located very far apart on the same chromosome
d. a or b
e. a or c
50. How are Okazaki fragments connected?
A. The nucleotides are in close enough proximity that they form together spontaneously.
B. DNA ligase joins the fragments together.
C. DNA polymerase joins the fragments together as the primer is replaced.
D. The cell heats up during DNA replication to ensure the fragments have enough energy to bond together.
E. The Okazaki fragments don’t have to be connected.
51. In dogs, two genes code for fur color. The first gene has a black and a white allele. Two black alleles cause pigment to be black, two white alleles cause pigment to be white, and a black and white allele together cause pigment to be gray. The second gene, which determines whether or not any pigment is placed, is epistatic over the first. Pigment will only be placed if the dog is homozygous recessive for the second gene. If two dogs that are heterozygous for both genes mate, what percentage of their offspring should be gray?
a. 1/2
b. 1/4
c. 1/8
d. 3/16
e. 9/16
52. Which of the following statements about replication origins is correct?
A. In both prokaryotes and eukaryotes, replication proceeds in both directions from each origin.
B. The two strands of DNA at the origin are separated, allowing the formation of a replication bubble.
C. Bacterial chromosomes have a single origin, but eukaryotic chromosomes have many origins.
D. In eukaryotic cells, the many replication bubbles fuse once replication is complete.
E. All of the abovE.
53. Which of the following is true about the production of polypeptides in prokaryotes?
a. introns must be excised from mRNA before translation
b. there are only twenty different codons used during translation
c. a poly-A tail must be added to mRNA to prevent degradation
d. groups of four nucleotides are used to code for a single amino acid
e. transcription and translation can occur simultaneously
54. A cell biologist found that two different proteins with largely different structures were translated from two different mRNAs. These mRNAs, however, were transcribed from the same template within the cell nucleus. Which mechanism below could best account for this?
A. A point mutation might have altered the gene.
B. The two proteins have different functions in the cell.
C. Different systems of DNA unpacking could result in two different mRNAs.
D. Exons from the same gene could be spliced in different ways to make different mRNAs.
E. Different transcription factors were involved in the transcription of the two mRNAs.
55. Which of the following is NOT true regarding eukaryotic transcription?
A. The promotor is the location where RNA polymerase binds.
B. The promotor follows the sequence GAGA.
C. Transcription factors are special proteins that help RNA polymerase bind.
D. The promotor, transcription factors, and RNA polymerase form the transcription initiation complex.
E. All of the above are true.
56. What happens directly after a tRNA moves to the P site?
A. It leaves the ribosome.
B. It transfers its growing peptide to the amino acid on the tRNA in the A site.
C. It accepts the growing peptide from the tRNA in the A site.
D. The ribosome breaks apart and protein synthesis ceases.
E. None of the above.
57. If the nontemplate strand of DNA has the sequence 5’-CGATGA-3’, which of the following would be the sequence of the mRNA molecule formed during transcription?
a. 3’-CGAUGA-5’
b. 5’-CGAUGA-3’
c. 3’-GCTACT-5’
d. 5’-GCTACT-3’
e. 3’-GCUACU-5’