6.1 Reproduction

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Question 3
Easy

Figure 1 shows a section of a double-stranded DNA molecule during replication.

![A schematic diagram of a DNA fragment consisting of two complementary strands. The sugar-phosphate backbones run vertically on both sides, consisting of alternating circles labeled 'X' and pentagons labeled 'Y'. Each pentagon 'Y' is attached to a central rectangular block containing a letter representing a nitrogenous base. There are 8 horizontal base pairs (rungs) in total, ordered from top to bottom as:

  1. T and A
  2. C and G
  3. A and T
  4. G and C
  5. T and A
  6. C and G
  7. A and T
  8. G and C Each of the 8 rungs connects a pair of pentagons on opposite sides of the ladder.](https://assets.mathsgenie.co.uk/aqa-qb/0653b6c3-46a8-487a-b56b-aaa2f2ca34f4.png)
a.

Identify the specific chemical components of a DNA nucleotide represented by the labels X and Y.

[2]
b.

Determine the total number of individual nucleotides shown in this model of a DNA molecule.

[2]

6.1 Reproduction Questions

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