Multiple Choice
During which stage of meiosis does independent assortment of chromosomes primarily occur?
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3. Extensions to Mendelian Inheritance
Understanding Independent Assortment
Multiple Choice
If 35% of an organism's DNA is thymine, what is the percentage of guanine?
A
20%
B
30%
C
15%
D
35%
Verified step by step guidance1
Recall Chargaff's rules, which state that in double-stranded DNA, the amount of adenine (A) equals thymine (T), and the amount of guanine (G) equals cytosine (C). This means \(\%A = \%T\) and \(\%G = \%C\).
Given that thymine (T) makes up 35% of the DNA, adenine (A) must also be 35% because \(\%A = \%T\).
Calculate the combined percentage of adenine and thymine: \(\%A + \%T = 35\% + 35\% = 70\%\).
Since the total percentage of all four bases must equal 100%, subtract the combined A and T percentage from 100% to find the combined percentage of guanine and cytosine: \(100\% - 70\% = 30\%\).
Because guanine and cytosine are present in equal amounts, divide the combined G and C percentage by 2 to find the percentage of guanine: \(\%G = \frac{30\%}{2}\).
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