1. The Molecular Basis of Inheritance
Chapter 16
The Molecular Basis of Inheritance

2. Tobacco mosaic virus has RNA rather than DNA as its genetic material. In a hypothetical situation where RNA from a tobacco mosaic virus is mixed with proteins from a related DNA virus, the result could be a hybrid virus. If that virus were to infect a cell and reproduce, what would the resulting "offspring" viruses be like?
tobacco mosaic virus
the related DNA virus
a hybrid: tobacco mosaic virus RNA and protein from the DNA virus
a hybrid: tobacco mosaic virus protein and nucleic acid from the DNA virus
a virus with a double helix made up of one strand of DNA complementary to a strand of RNA surrounded by viral protein
Answer: a
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #4

3. Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. What percent of the nucleotides in this sample will be thymine? 12 24 31 38
It cannot be determined from the information provided.
Answer: a
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #16

4. In an analysis of the nucleotide composition of DNA, which of the following is true?
A = C
A = G and C = T
A + C = G + T
A + T = G + C
Both B and C are true
Answer: c
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #21

5. A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life form that has DNA. You grow the cells in 15N medium for several generations and then transfer it to 14N medium. Which pattern in this figure would you expect if the DNA were replicated in a conservative manner?
Answer: b
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #24 a. b. c. d. e.

6. In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?
A = G
A + G = C + T
A + T = G + T
A = C
G = T
Answer: b
Source: Campbell/Reece - Biology, Seventh Edition, EOC Self-Quiz Question #5

7. Imagine the following experiment is done: Bacteria are first grown for several generations in a medium containing the lighter isotope of nitrogen, 14N, then switched into a medium containing 15N. The rest of the experiment is identical to the Meselson and Stahl experiment. Which of the following represents the band positions you would expect after two generations? *
Answer: e
Source: Campbell/Reece - Biology, Seventh Edition, EOC Process of Science Question
Discussion Notes for the Instructor
There are several questions which can be asked to guide the discussion of this question, including:
Which isotope will the new nucleotides contain?
As DNA is being replicated the new backbone (strand) will contain which isotope?
How many templates are formed from one molecule of DNA?
Using these questions as an outline. discussion of the choices might look like this:
Choice A, since the original 14N labeled backbones will act as templates with new 15N nucleotides there should an intermediate band.
Choice B, the intermediate band should have a mass exactly half way between the 14N and 15N marks
Choice C, since there are no new 14N labeled nucleotides there can be no bands that are just 14N
Choice D, since there are no new 14N labeled nucleotides there can be no bands that are just 14N
Choice E, correct

8. You are trying to support your hypothesis that DNA replication is conservative; i.e., parental strands separate; complementary strands are made, but these new strands join together to make a new DNA molecule and the parental strands rejoin. You take E. coli that had grown in a medium containing only heavy nitrogen (15N) and transfer a sample to a medium containing light nitrogen (14N).
Answer: c
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #20

9. (cont.) After allowing time for only one DNA replication, you centrifuge a sample and compare the density band(s) formed with control bands for bacteria grown on either normal 14N or 15N medium. Which band location would support your hypothesis of conservative DNA replication?
Answer: c
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #20

10. Using the experiment explained in the previous question, which centrifuge tube would represent the band distribution obtained after one replication showing that DNA replication is semiconservative?
Answer: a
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #21

11. Chapter 17
From Gene to Protein

12. A mutation results in a defective enzyme a. In the following simple metabolic pathway, what would be a consequence of that mutation?
enzyme a
enzyme b
a b c
an accumulation of A and no production of B and C
an accumulation of A and B and no production of C
an accumulation of B and no production of A and C
an accumulation of B and C and no production of A
an accumulation of C and no production of A and B
Answer: a
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #3

13. If proteins were composed of only 12 different kinds of amino acids, what would be the small-est possible codon size in a genetic system with four different nucleotides? 1 2 3 4 12
Answer: b
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #9

14. A portion of the genetic code is UUU = phenylalanine, GCC = alanine, AAA = lysine, and CCC = proline. Assume the correct code places the amino acids phenylalanine, alanine, and lysine in a protein (in that order). Which of the following DNA sequences would substitute proline for alanine?
AAA-CGG-TTA
AAT-CGG-TTT
AAA-CCG-TTT
AAA-GGG-TTT
AAA-CCC-TTT
Answer: d
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #20

15. A particular triplet of bases in the coding sequence of DNA is AAA
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
TTT.
UUA.
UUU.
AAA.
either UAA or TAA, depending on wobble in the first base.
Answer: d
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #39

16. tRNA Anticodon Amino Acid
A part of an mRNA molecule with the following sequence is being read by a ribosome: 5' CCG-ACG 3' (mRNA). The following activated transfer RNA molecules are available. Two of them can correctly match the mRNA so that a dipeptide can form.
tRNA Anticodon
Amino Acid
GGC
Proline
CGU
Alanine
UGC
Threonine
CCG
Glycine
ACG
Cysteine
CGG
The dipeptide that will form will be
cysteine-alanine.
proline-threonine.
glycine-cysteine.
alanine-alanine.
threonine-glycine.
Answer: b
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #42

17. This figure represents tRNA that recognizes and binds a particular amino acid (in this instance, phenylalanine). Which of the following triplets of bases on the mRNA strand codes for this amino acid?
UGG
GUG
GUA
UUC
CAU
Answer: d
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #44

18. Each of the following is a modification of the sentence THECATATETHERAT. A. THERATATETHECAT B. THETACATETHERAT C. THECATARETHERAT D. THECATATTHERAT E. CATATETHERAT Which of the above is analogous to a frameshift mutation? A B C D E
Answer: d
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #68

19. Each of the following is a modification of the sentence THECATATETHERAT. A. THERATATETHECAT B. THETACATETHERAT C. THECATARETHERAT D. THECATATTHERAT E. CATATETHERAT Which of the above is analogous to a single substitution mutation? A B C D E
Answer: c
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #69

20. What is the relationship among DNA, a gene, and a chromosome?
A chromosome contains hundreds of genes, which are composed of protein.
A chromosome contains hundreds of genes, which are composed of DNA.
A gene contains hundreds of chromosomes, which are composed of protein.
A gene is composed of DNA, but there is no relationship to a chromosome.
A gene contains hundreds of chromosomes, which are composed of DNA.
Answer: b
Source: Barstow - Test Bank for Biology, Seventh Edition, Question #75

21. A biologist inserts a gene from a human liver cell into the chromosome of a bacterium. The bacterium then transcribes this gene into mRNA and translates the mRNA into protein. The protein produced is useless. The biologist extracts the protein and mature mRNA that codes for it. When analyzed you would expect which of the following results? *
the protein and the mature mRNA are longer than in human cells
the protein and mature mRNA are shorter than expected
the protein is longer and the mRNA is shorter than expected
the protein is shorter and the mRNA is longer than expected
Answer: a
Source: Campbell/Reece - Biology, Seventh Edition, EOC Process of Science Question
Discussion Notes for the Instructor
There are several questions which can be asked to guide the discussion of this question, including:
What are the differences between the way the genetic information in prokaryotes and eukaryotes is packaged?
How do transcription and translation differ in prokaryotes and eukaryotes?
Using these questions as an outline, discussion of the choices might look like this:
Choice A, correct
Choice B, eukaryotes contain introns that are normally removed after transcription. In bacteria these introns would not be removed and then subsequently would be translated
Choice C, the protein would not be expected to be longer if the mRNA is shorter
Choice D, while it is possible for the protein to be shorter, owing to a termination sequence being found in what was an intron, this is unlikely.

22. How is the template strand for a particular gene determined?
It is the DNA strand that runs from the 5' → 3' direction.
It is the DNA strand that runs from the 3' → 5' direction.
It depends on the orientation of RNA polymerase, whose position is determined by particular sequences of nucleotides within the promoter.
It doesn’t matter which strand is the template because they are complementary and will produce the same mRNA.
The template strand always contains the TATA box.
Answer: c
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #5

23. Answers
Ch 16 A C B E
Ch 17 A B D C