Exam code: 9BN0
Draw and label a single DNA nucleotide.
Explain two features of DNA that help stabilse its structure.
A sample of DNA contained 23% Thymine.
Calculate the percentages of Adenine and Guanine.
The diagram below shows a strand of DNA.
Name the type of bond between:
(i) Complementary bases
(1)
(ii) Adjacent nucleotides
(1)
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RNA has a similar structure to DNA
(i) Which of the following is true for the structure of RNA?
(1)
☐ | A | RNA can contain the bases adenine, guanine, uracil, thymine and cytosine |
☐ | B | RNA is a polynucleotide containing a base, pentose sugar deoxyribose and a phosphate group |
☐ | C | RNA is a polynucleotide held together by phosphodiester bonds |
☐ | D | The complimentary bases in all RNA are held together by hydrogen bonds |
(ii) Name two types of RNA.
(1)
Compare and contrast the structures and functions of DNA and RNA.
RNA is a polymer.
State the evidence in the diagram that shows RNA is a polymer.
Name the parts in the diagram labelled X, Y and Z.
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Describe the structure of DNA.
DNA is a double helix.
Describe two advantages to DNA having a double helix.
The bases of DNA and RNA occur in two forms: purines and pyrimidines.
(i) Describe the difference in the structure of purines and pyrimidines.
(2)
(ii) Of the five different nitrogenous bases, some are purines, some are pyrimidines.
Which combination of bases is correct?
(1)
| Purines | Pyrimidines |
|---|---|---|
A | A, G, C, T | U |
B | A, G | T, C, U |
C | T, C, U | A, G |
D | A, T | C, G, U |
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DNA is transcribed into an RNA structure called pre-mRNA using complementary base pairs.
Complete the table below with the base sequence of the pre-mRNA strand from which the DNA will be transcribed.
DNA | T | A | T | C | C | A | G | A | C | T | C | C |
Pre-mRNA |
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The DNA strands are described as antiparallel.
With reference to DNA replication, explain the importance of the antiparallel nature of DNA strands.
The diagram shows the structure of one strand of DNA.
Name the molecules labelled W, X, Y and Z
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The diagram below shows a representation of part of a DNA molecule.
Identify the structures labelled A, B, and D.
Identify one type of bond found within the structure labelled C in the diagram at part (a).
Explain how the structure of DNA relates to its functions.
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