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(a) DNA molecules contain base pairs - Edexcel - GCSE Biology - Question 2 - 2022 - Paper 1

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(a) DNA molecules contain base pairs. Describe how the base pairs are bonded together in a DNA molecule. (b) Figure 1 shows part of a DNA molecule. T T G A T T G C... show full transcript

Worked Solution & Example Answer:(a) DNA molecules contain base pairs - Edexcel - GCSE Biology - Question 2 - 2022 - Paper 1

Step 1

Describe how the base pairs are bonded together in a DNA molecule.

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Answer

In a DNA molecule, the base pairs are held together by weak hydrogen bonds. Each base forms specific pairs: adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). These hydrogen bonds stabilize the DNA structure, allowing it to maintain its double helix shape.

Step 2

Write the code for the complementary DNA strand in Figure 1.

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Answer

The complementary DNA strand for Figure 1 is:

A A C T A A C G C A T T

Step 3

Which is the maximum number of amino acids coded for by this strand of DNA?

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Answer

The maximum number of amino acids coded for by this strand of DNA is C (6). This is because there are 18 bases in the strand, and since three bases code for one amino acid, the calculation is:

rac{18}{3} = 6

Step 4

What is the shape of a DNA molecule?

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Answer

The shape of a DNA molecule is D (double helix).

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