Question
Refer to the paragraph and table to answer questions 23 and 24.
* 2 points
The table shows data that Chargaff collected on nitrogenous bases in the DNA in five organisms.
23. Which statement did Chargaff conclude based on these data? (Note: A letter in brackets, such as [A] or [C], refers to the concentration of one of the nitrogenous bases.
Percentages of Bases in Five Organisms
Source of DNA
C
Streptococcus
29.8
31.6
20.5
18.0
Yeast
A
T
G
31.3
32.9
18.7
17.1
Herring
27.8
27.5
22.2
22.6
Human
30.9
29.4
19.9
19.8
E.coli
24.7
23.6
26.0
25.7
a in DNA molecules, [T][A] > [G] > [C]
b. in DNA molecules [A] = [G] and [C] = [T]
c. in DNA molecules, [A]=[ TI and [C] = [G]
d in single stranded DNA molecules, [A] = [T] = [C] = [G]
* 2 points
The table shows data that Chargaff collected on nitrogenous bases in the DNA in five organisms.
23. Which statement did Chargaff conclude based on these data? (Note: A letter in brackets, such as [A] or [C], refers to the concentration of one of the nitrogenous bases.
Percentages of Bases in Five Organisms
Source of DNA
C
Streptococcus
29.8
31.6
20.5
18.0
Yeast
A
T
G
31.3
32.9
18.7
17.1
Herring
27.8
27.5
22.2
22.6
Human
30.9
29.4
19.9
19.8
E.coli
24.7
23.6
26.0
25.7
a in DNA molecules, [T][A] > [G] > [C]
b. in DNA molecules [A] = [G] and [C] = [T]
c. in DNA molecules, [A]=[ TI and [C] = [G]
d in single stranded DNA molecules, [A] = [T] = [C] = [G]
Answers
GPT-4o mini
Based on Chargaff's rules, the conclusion that can be drawn from the data provided in the table is:
**b. in DNA molecules [A] = [T] and [C] = [G]**
Chargaff's rules state that in double-stranded DNA, the amount of adenine (A) is equal to thymine (T), and the amount of cytosine (C) is equal to guanine (G). The data reflects this principle, as the percentages of these bases in the samples from different organisms align with this conclusion.
**b. in DNA molecules [A] = [T] and [C] = [G]**
Chargaff's rules state that in double-stranded DNA, the amount of adenine (A) is equal to thymine (T), and the amount of cytosine (C) is equal to guanine (G). The data reflects this principle, as the percentages of these bases in the samples from different organisms align with this conclusion.