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BIOL. 303 EXAM II 10/26/
This exam consists of 40 multiple choice questions worth 2.5 points each. On the separate answer sheet , please fill-in the single best choice for each question. Please bubble-in your name on the answer sheet, leaving a space between first and last names. Also, bubble-in the last 5 digits of your social security number under “ID NUMBER” beginning in the left-most column. Good luck!
1. In humans, the genetic basis for determining the sex “male” is accomplished by A. the Y chromosome B. the presence of only one X chromosome C. a balance between the number of X chromosomes and the number of haploid sets of autosomes D. multiple alleles scattered throughout the autosomes 2. Klinefelter syndrome in humans, which leads to underdeveloped testes and sterility, is caused by which chromosomal condition? A. 47, XXY B. 47, 21+ C. 45, X D. 47, XYY
- In birds, sex is determined by a ZW chromosome scheme, which is much like the typical XY scheme seen in humans and many other organisms. However, in birds the system is reversed. Males are ZZ (similar to XX in humans) and females are ZW (similar to XY in humans). A lethal recessive allele that causes death of the embryo occurs on the Z chromosome in pigeons. What would be the sex ratio in the offspring of a cross between a male heterozygous for the lethal allele and a normal female? A. 2:1 male to female B. 3:1 male to female C. 1:2 male to female D. 1:1 male to female
- Hemophilia is caused by a sex-linked recessive gene. Assume that a man with hemophilia marries a normal woman whose father had hemophilia. What is the probability that their first born child has hemophilia? A. 1/ B. 1/
C. 1/
D. 1/
- What is the expected number of Barr bodies in an individual with the karyotype XYYY? A. 0 B. 1 C. 2 D. 3
- The genotype XYYY produces a A. female in Drosophila and a female in humans. B. female in Drosophila and a male in humans. C. male in Drosophila and a male in humans. D. male in Drosophila and a female in humans.
- When an organism gains or loses one or more chromosomes but not a complete haploid set, the condition is known as A. polyploidy B. aneuploidy C. triploidy D. trisomy
- When a diploid organism gains a complete haploid set of chromosomes, the condition is known as A. haploidy B. aneuploidy C. triploidy D. trisomy
- A somatic cell from a human with a trisomy would contain a total of how many chromosomes? A. 46 B. 69 C. 45 D. 47
D. single translocations in the X chromosome.
- Trisomy 21, or Down syndrome, usually occurs when there is a normal diploid chromosomal complement of 46 chromosomes plus one extra chromosome #21. While there is impaired fertility of both sexes, females are more likely to be fertile than males. Assume that children are born to a female with Down syndrome and a normal 46- chromosome male. What proportion of the offspring would be expected to have Down syndrome? A. One half of the offspring will be expected to have Down syndrome. B. None of the offspring would be expected to have Down syndrome. C. All the children would be expected to have Down syndrome. D. Two-thirds of the offspring would be expected to have Down syndrome.
- Cells from an individual with the familial form of Down syndrome will likely contain how many chromosomes? A. 47 B. 45 C. 23 D. 46
- DNA, originally called “nuclein,” was discovered by A. Hershey and Chase B. Watson and Crick C. Friedrich Miescher D. Klug, Cummings, Spencer, and Palladino
- 32 P and 35 S were used in the classic experiment conducted by Hershey and Chase because A. 32 P labels DNA and 35 S labels protein B. 32 P labels protein and 35 S labels DNA C. both radioisotopes label an entire phage including DNA and protein D. 32 P labels DNA and 35 S labels RNA
- The basic structure of a nucleotide includes which of the following components? A. amino acids. B. base, sugar, phosphate. C. phosphorous and sulfate. D. all of the above.
- If 20% of the nitrogenous bases in a sample of DNA from a particular organism is thymine, what percentage should be cytosine? A. 15% B. 30% C. 40% D. 35%
- Which of the following clusters of terms accurately describes DNA as it is generally viewed to exist in prokaryotes and eukaryotes? A. Double-stranded, parallel, (A+T)/(C+G)= variable, (A+G)/(C+T)=1. B. Single-stranded, antiparallel, (A+T)/(C+G)=1.0, (A+G)/C+T)=1. C. Double-stranded, antiparallel, (A+T)/(C+G)=variable, (A+G)/(C+T)=1. D. Double-stranded, antiparallel, (A+T)/C+G)=1.0, (A+G)/(C+T)=variable
- Which of the following is a pyrimidine base? A. B. C. D.
- The two strands of a DNA helix are held together (to each other) by A. covalent bonds. B. hydrogen bonds. C. phosphodiester bonds. D. glycosidic bonds.
- The enzyme that appears to be inappropriately expressed in cancer cells and helps to maintain the very ends of eukaryotic chromosomes is called A. topoisomerase. B. ligase. C. telomerase. D. terminase.
- The “Hayflick limit” refers to A. How far a DNA polymerase can travel along a template B. The limited number of cell divisions a human cell can undergo in vitro C. The temperature at which most DNA melts. D. The farthest distance anyone has ever thrown a piece of hay. 30. In addition to highly repetitive and unique DNA sequences, a third category of DNA sequences exists. What is it called and what types of elements are involved? A. composite DNA, telomeres and heterochromatin B. dominant DNA, euchromatin and heterochromatin C. multiple gene family DNA, hemoglobin and 5.0S RNA D. middle repetitive DNA, SINEs, LINEs, and VNTRs
- The equation L = T + W has something to do with A. DNA supercoiling B. Mendel’s experiments C. balanced translocations D. None of the above
- Chromatin of eukaryotes is organized into repeating interactions with protein octomers called nucleosomes. Nucleosomes contain which class of protein molecules? A. histones B. glycoproteins C. lipids D. nonhistone chromosomal proteins
- An enzyme that controls supercoiling in DNA is called A. telomerase B. polymerase C. reverse transcriptase D. topoisomerase
- Mutations which arise in nature from no particular artificial agent are called A. induced mutations. B. spontaneous mutations. C. chromosomal aberrations. D. cosmic mutations.
- Microsatellite DNA sequences A. are present in one copy per haploid genome B. are completely deleted in Patau syndrome C. resemble tiny weather satellites D. are present in eukaryote genomes as tandem repeats of a very short sequence
- In a transition mutation, A. a pyrimidine substitutes for a purine. B. a purine substitutes for a purine. C. a single nucleotide is inserted D. a translocation occurs.
- Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are genetically incapable of repairing dimers at normal rates. Such individuals are likely to suffer from A. xeroderma pigmentosum. B. phenylketonuria. C. muscular dystrophy. D. Huntington disease.
- The DNA repair pathway that starts with the action of a DNA glycosylase is A. nucleotide excision repair B. photoreactivation C. base excision repair
Answer Key Q: 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,15,16,17,18,19,20, A: A, A, A, D, A, B, B, C, D, B, D, C, C, B, A, D, C, A, B, B, Q: 21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39, A: C, A, B, D, D, D, A, C, B, D, A, A, D, B, D, B, A, C, A, C
