Fig. 1 shows a short section of a DNA molecule built by a student using coloured model pieces. Each rung represents a pair of bases. The student removes the...
Question 1 Report
Fig. 1 shows a short section of a DNA molecule built by a student using coloured model pieces. Each rung represents a pair of bases. The student removes the colours before asking another student to identify how the bases are paired. DNA in the nucleus of nearly all human body cells carries the instructions for making proteins.
(a) Name the structure labelled X. [1]
(b) Complete the base-pair rule: adenine pairs with __________ and cytosine pairs with __________. [2]
(c) Use Fig. 1 to write the sequence of bases on the right-hand strand, from top to bottom. [1]
(d) Explain how the base sequence in DNA can affect a feature of a person. [3]
Answer Details
(a) X labels the DNA molecule, which has a double helix structure. [1]
(b) Adenine pairs with thymine, and cytosine pairs with guanine. These are complementary base pairs. [2]
(c) Reading the right-hand strand from top to bottom gives T G C A. [1]
(d) A sequence of DNA bases forms a gene, or contains a genetic code. The code determines the sequence of amino acids used to make a protein. Different proteins affect cell structure or function, so they can affect a person's features. [3]
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