Calculate DNA base percentages (A = T, C = G)
12th grade (Year 13 in England) · 16 questions · Common Core: NGSS.HS-LS3-1, NGSS.SEP 5 · England: GCSE Biology: DNA structure, A level Biology: Nucleic acids
Name
Date
Score/ 16
Question 1
Why does DNA with a high percentage of C and G need more energy to separate its strands?
- A. C–G DNA is single-stranded
- B. A and T are not paired
- C. C and G are heavier atoms
- D. C–G pairs are held by three hydrogen bonds, A–T pairs by two
Question 2
A double-stranded DNA fragment has 1000 bases in total. 350 of them are cytosine. How many are adenine?
Answer
Question 3
In a sample of double-stranded DNA, 30 % of the bases are thymine (T). What percentage are cytosine (C)?
Answer%
Question 4
Chargaff found A ≈ T and C ≈ G in many species. Which model did this support?
- A. DNA as a single straight strand
- B. complementary base pairing in the double helix
- C. a triple helix
- D. proteins carrying genetic information
Question 5
A double-stranded DNA fragment has 600 bases in total. 120 of them are cytosine. How many are adenine?
Answer
Question 6
In a sample of double-stranded DNA, 26 % of the bases are adenine (A). What percentage are guanine (G)?
Answer%
Question 7
A sample has 21 % A, 29 % T, 25 % C and 25 % G. What does this suggest?
- A. It is normal double-stranded DNA
- B. The measurements prove an error in all DNA
- C. It is likely single-stranded DNA, because A ≠ T
- D. It must be RNA because it contains T
Question 8
A double-stranded DNA fragment has 400 bases in total. 80 of them are cytosine. How many are adenine?
Answer
Question 9
In a sample of double-stranded DNA, 15 % of the bases are thymine (T). What percentage are cytosine (C)?
Answer%
Question 10
Chargaff found A ≈ T and C ≈ G in many species. Which model did this support?
- A. complementary base pairing in the double helix
- B. proteins carrying genetic information
- C. a triple helix
- D. DNA as a single straight strand
Question 11
A double-stranded DNA fragment has 1000 bases in total. 200 of them are cytosine. How many are adenine?
Answer
Question 12
In a sample of double-stranded DNA, 15 % of the bases are adenine (A). What percentage are guanine (G)?
Answer%
Question 13
Chargaff found A ≈ T and C ≈ G in many species. Which model did this support?
- A. a triple helix
- B. DNA as a single straight strand
- C. complementary base pairing in the double helix
- D. proteins carrying genetic information
Question 14
A double-stranded DNA fragment has 600 bases in total. 120 of them are cytosine. How many are adenine?
Answer
Question 15
In a sample of double-stranded DNA, 20 % of the bases are adenine (A). What percentage are guanine (G)?
Answer%
Question 16
A sample has 21 % A, 29 % T, 25 % C and 25 % G. What does this suggest?
- A. The measurements prove an error in all DNA
- B. It is likely single-stranded DNA, because A ≠ T
- C. It must be RNA because it contains T
- D. It is normal double-stranded DNA
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