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10 questions
In the reading, the author uses the word "backbone" in line 2 and 22 to indicate that
only very long chains of DNA can be taken from an organism with a spinal column.
the main structure of a chain in a DNA molecule is composed of repeating units.
a chain in a DNA molecule consists entirely of phosphate groups or of sugars.
nitrogenous bases form the main structural unit of DNA.
A student claims that nitrogenous bases pair randomly with one another. Which of the following statements in the reading passage contradicts the student's claim?
Lines 2-3 ("To each... types")
Line 5 ("So far... irregular")
Lines 13-14 ("The bases... other")
Lines 15-16 ("One member... chains")
In the second paragraph (lines 7-11), what do the authors claim to be a feature of biological interest?
The chemical formula of DNA
The common fiber axis
The X-ray evidence
DNA consisting of two chains
The author's main purpose of including the information about X-ray evidence and density is to
Establish that DNA is the molecule that carries the genetic information
Present an alternative hypothesis about the composition of a nucleotide
Provide support for the authors' claim about the number of chains in a molecule of DNA
Confirm the relationship between the density of DNA and the known chemical formula of DNA.
Based on the passage, the authors' statement "If a pair consisted of two purines, for example, there would not be enough room for it" (lines 16-17) implies that a pair
of purines would be larger than the space between a sugar and a phosphate group
of purines would be larger than a pair consisting of a purine and a pyrimidine
of pyrimidines would be larger than a pair of purines
consisting of a purine and a pyrimidine would be larger than a pair of pyrimidines
The authors' use of the words "exact", "specific", and "complement" in lines 25-27 functions mainly to
Confirm that the nucleotide sequences are known for most molecules of DNA
Counter the claim that the sequences of bases along a chain can occur in any order
Support the claim that the phosphate-sugar backbone of the authors' model is completely regular
Emphasize how one chain of DNA may serve as a template to be copied during DNA replication
Based on the table and passage, which choice gives the correct percentages of the purines in yeast DNA?
17.1% and 18.7%
17.1%% and 32.9%
18.7% and 31.3%
31.3% and 32.9%
Do the data in the table support the authors' proposed pairing of bases in DNA?
Yes, because for each given organism, the percentage of adenine is closest to the percentage of thymine, and the percentage of guanine is closest to the percentage of cytosine
Yes, because for each given organism, the percentage of adenine is closest to the percentage of guanine, and the percentage of cytosine is closest to the percentage of thymine
No, because for each given organism, the percentage of adenine is closest to the percentage of thymine, and the percentage of guanine is closest to the percentage of cytosine
No, because for each given organism, the percentage of adenine is closest to the percentage of guanine, and the percentage of cytosine is closest to the percentage of thymine
According to the table, which of the following pairs of base percentages in sea urchin DNA provides evidence in support of the base pairing rules?
17.3% and 17.7%
17.3% and 32.1%
17.3% and 32.8%
17.7% and 32.8%
Based on the table, is the percentage of adenine in each organism's DNA the same or does it vary, and which statement made by the authors is most consistent with that data?
The same; "Two of... pyrimidines" (lines 3-4)
The same; "The important... structure" (lines 14-15)
It varies; "Adenine... thymine" (lines 20-21)
It varies; "It follows... information" (lines 23-25)
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