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Edexcel AS Biology - what do you need to be able to draw?

Are you required to draw certain things? E.g. formation of glycosidic bonds? The syllabus doesn't seem to specify what you need to be able to draw yet there are a lot of diagrams in the revision guides. Thanks :smile:
Sometimes the structure of an amino acid, what happens during a condensation reaction/hydrolysis, so glucose molecules, both alpha and beta :smile:

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Reply 2
Original post by Lucy96
Sometimes the structure of an amino acid, what happens during a condensation reaction/hydrolysis, so glucose molecules, both alpha and beta :smile:


Thanks for the reply. So, for example, we would need to be able to draw lactose being formed by B-glucose and galactose? Why does the specification not say this? It just says:

4. Describe how monosaccharides join to form disaccharides (sucrose, lactose and maltose) and polysaccharides (glycogen and amylose) through condensation reactions forming glycosidic bonds, and how these can be split through hydrolysis reactions.
Original post by GradMed
Thanks for the reply. So, for example, we would need to be able to draw lactose being formed by B-glucose and galactose? Why does the specification not say this? It just says:


It's okay :smile: I think so, I'm sure a past paper I did asked me to draw the formation of maltose through a condensation reaction! I have no idea why it doesn't say it. It's rare for it to come up but I've definitely seen it before!

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Reply 4
Original post by Lucy96
It's okay :smile: I think so, I'm sure a past paper I did asked me to draw the formation of maltose through a condensation reaction! I have no idea why it doesn't say it. It's rare for it to come up but I've definitely seen it before!

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Do you remember if it asked you to draw it from scratch or just to finish it off with the glycosidic bond? I hope we're not expected to know the diagrams for all of these?! There are so many different variations, I would definitely get some hydroxyl groups on the wrong carbon atom etc.
(edited 10 years ago)
Original post by GradMed
Do you remember if it asked you to draw it from scratch or just to finish it off with the glycosidic bond? I hope we're not expected to know the diagrams for all of these?! There are so many different variations, I would definitely get some hydroxyl groups on the wrong carbon atom etc.


They'd usually give you the structures of the sugar units first
Reply 6
Original post by Changing Skies
It's okay :smile: I think so, I'm sure a past paper I did asked me to draw the formation of maltose through a condensation reaction! I have no idea why it doesn't say it. It's rare for it to come up but I've definitely seen it before!

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Do we have to know how to draw galactose and fructose as well?

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