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A level Biology: Post your doubts here!

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Idk how there is absence of non-reducing sugars here :-/
Could anyone explain why C is the answer ad not A?

A student carried out four tests for biological molecules on a sample of milk.
The tests and their results were as follows.

● Heating to 80 °C with Benedict’s solution gave a brick red colour.
● Adding Biuret solution gave a purple colour. ● Adding iodine solution gave an orange colour.
● Boiling with acid, followed by neutralisation, then heating to 80 °C with Benedict’s solution gave a brick red colour.

Which biological molecules must be present in the milk?
1 non-reducing sugars
2 protein
3 reducing sugars
4 starch


A 1, 2 and 3
B 1 and 2 only
C 2 and 3 only
D 3 and 4
 
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Idk how there is absence of non-reducing sugars here :-/
Could anyone explain why C is the answer ad not A?

A student carried out four tests for biological molecules on a sample of milk.
The tests and their results were as follows.

● Heating to 80 °C with Benedict’s solution gave a brick red colour.
● Adding Biuret solution gave a purple colour. ● Adding iodine solution gave an orange colour.
● Boiling with acid, followed by neutralisation, then heating to 80 °C with Benedict’s solution gave a brick red colour.

Which biological molecules must be present in the milk?
1 non-reducing sugars
2 protein
3 reducing sugars
4 starch


A 1, 2 and 3
B 1 and 2 only
C 2 and 3 only
D 3 and 4
Test for reducing and non-reducing sugar both gave brick red ppt so there is no proof that non-reducing sugar will also be present...the question asks about the molecules which MUST be present, not those which CAN be present
 
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Test for reducing and non-reducing sugar both gave brick red ppt so there is no proof that non-reducing sugar will also be present...the question asks about the molecules which MUST be present, not those which CAN be present

Ohww nktt...........thanks :)
 
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Test for reducing and non-reducing sugar both gave brick red ppt so there is no proof that non-reducing sugar will also be present...the question asks about the molecules which MUST be present, not those which CAN be present
You saw the examiner report right ......
 
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oh i see thanks :D
apparently i confused the Haem group to nitrogen but is actually iron xD
 
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Bio Screenshot (14).png Screenshot (5).png Bombs Away!!!Screenshot (13).png I understand that the objective lens should be x10 but why must the eyepiece lens be x5?
 
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I understand that the objective lens should be x10 but why must the eyepiece lens be x5?
The TOTAL magnification must be calculated...so for the largest number of cells, the total magnification must be lowest which is x50 for A
 
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