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AQA Jun 2017 Paper 2 Q9
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![190 9 Use the Data Booklet to help you answer these questions. DNA exists as two strands of nucleotides in the form of a double helix with hydrogen bonding between the two strands. 0 9 . 1 A deoxyribose molecule in a strand of DNA is shown. 0 9 . 2 Name the types of group attached to 2-deoxyribose at positions X and Y. [2 marks] In the DNA double helix, adenine is linked by hydrogen bonds to a molecule in the other strand of DNA. Complete the diagram below to show the other molecule and the hydrogen bonds between it and adenine. [2 marks] *19* Turn overIB/M/Jun17/7405/2<br />](https://learnah.org/wp-content/uploads/2018/08/June_2017_QP_-_Paper_2_AQA_Chemistry_A-Level_9.jpg)
![MARK SCHEMEA-LEVEL CHEMISTRY7405/2JUNE 2017 Answers Mark Additional Comments/Guidance Xbase Yphosphate (group) Ignore organic Any mention of sugar in either loses that mark If not Thymine CE=0 Question 09.1 09.2 Correct structure scores 2, penalise by 1 each error instructure of thymineorientation of thyminehydrogen bonding Total Ignore lp on N and O Dont penalise non-linear H bonds on RHS of thymineallow with or without H or[DNA strand] 27 of 32<br />](https://learnah.org/wp-content/uploads/2018/08/June_2017_MS_-_Paper_2_AQA_Chemistry_A-Level_9.jpg)