Edexcel AS Biology - 6B101 + 6B102 - Unit 1 and Unit 2 Exam Discussion Thread

Could someone please explain all of the methods for the enzyme experiments please

There's a decrease in ventricular pressure so it allows the cycle to start again?

Someone correct me if I'm wrong


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Also there is a higher pressure in the vena cava and pulmonary vein hence causes av valves to open and refills the atrias

Can someone please tell me the steps of the Meselson and stahl experiment - the only thing I know is that they tried to prove that DNA underwent semi conservative replication, using DNA from e-coli bacteria

My teacher says they don't expect you to remember the experiment as they'll give you relevant information but can ask you to draw bands. Can you do that?

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My teacher says they don't expect you to remember the experiment as they'll give you relevant information but can ask you to draw bands. Can you do that?

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omg can you please explain how to draw the bands, i really dont get that

For everyone who only learn the CGP book (like me)

This is a list of what is missed out or is in a lot greater detail that the CGP book:

This is from an official edexcel mark scheme, and I have edited it to make it versatile for any experiment containing an enzyme and a substrate. Simply substitute the named enzyme/substrate from the question in the exam. If it doesn't give you one, then chose a simple one like a triglyceride and lipase.

1. reference to use of a range of substrate (named substrate) concentrations ;

2. idea of mixing (enzyme and substrate) ;

3. identification of a suitable dependent variable. pH ;

4. description of how to measure the dependent variable e.g. use of pH indicator ;

5. reference to measuring time ;

6. description of how to calculate (initial) rate of reaction ;

7. idea of repeating experiment without the enzyme ;

8. idea of control of enzyme (named enzyme) concentration;

9. reference to one other named controlled variable (e.g. temperature, type of [named substrate],volume of solutions) ;

10. reference to {replicates / repeats} (using the same [named substrate] concentration) ;

Type in McGraw Hill Mehelson and Stahl and there's a short clip explaining how it works. Just remember first generation there is one heavy nitrogen 15 band and one normal nitrogen 14 band causing it to be in the middle and in the second generation there's one light band and one medium band. I draw a picture on the whiteboard for you

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Pinocytosis? Human genome project? (Thought that was part of unit 2)

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Can you do this for all the other ones If you don't mind?

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Do we ever have to draw a monohybrid cross or can i stick to the punnet sauare ???