2 marksDraw and label a single DNA nucleotide.
2 marksExplain two features of DNA that help stabilse its structure.
2 marksA sample of DNA contained 23% Thymine.
Calculate the percentages of Adenine and Guanine.
2 marksThe 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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2 marksRNA 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)
5 marksCompare and contrast the structures and functions of DNA and RNA.
1 markRNA is a polymer.
State the evidence in the diagram that shows RNA is a polymer.
3 marksName the parts in the diagram labelled X, Y and Z.
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5 marksDescribe the structure of DNA.
2 marksDNA is a double helix.
Describe two advantages to DNA having a double helix.
3 marksThe 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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1 markDNA 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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3 marksThe DNA strands are described as antiparallel.
With reference to DNA replication, explain the importance of the antiparallel nature of DNA strands.
4 marksThe diagram shows the structure of one strand of DNA.
Name the molecules labelled W, X, Y and Z
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3 marksThe diagram below shows a representation of part of a DNA molecule.
Identify the structures labelled A, B, and D.
1 markIdentify one type of bond found within the structure labelled C in the diagram at part (a).
6 marksExplain how the structure of DNA relates to its functions.
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