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AQA A-level Biology Unit 1 26th May 2016

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Original post by Kira Yagami
For the one about whole between the vent and atria..

I said blood would flow back into atria so less blod would be pumped around the body.

Blood carries oxygen so there would be less blood flow to cells so they would receive less oxygen..

/ diffusion gradient is reduced...

Something like that.


Yeah i put something like, that the deoxygenated blood would mix with the oxygenated so overall there would be blood carrying less oxygen flowing out of the aorta to the body tissues, whilst blood slightly oxygenated would return to the lungs via the pulmonary artery
Magnification answer?
Original post by EmmaHarvard
Magnification answer?


2.7 something
Reply 103
Last year it was 42 (I think) for an A, so hoping it's similar this year.

I found it ok but almost ran out of time, also agree the last two questions were weird.
Alveoli burst - Dec SA
Elastin permanently stretched - CG not maintained
I thought the question said there was hole between the left and right ventricles, not the ventricles and the atria? I put that oxygenated and deoxygenated blood would become mixed together so some deoxygenated blood would be transported to the tissues.
Milk questions, what I put:
Heat to destroy lactose or use lactase to hydrolyse lactose
In morning means the stomachs and lumens are empty, provides benchmark
Different milk contain different concentrations of lactose
Scientists may recommend not drinking sugary drinks or sugary foods such as bread? Allows baseline to be established, effect of milk can be compared therefore
Participants may lie about symptoms - unreliable
Those with untreated milk 3x more likely to suffer bloating, overall untreated milk has more side affects, diarrhoea more prevalent with treated milk


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The 3 markers the end:

(about blood transfusion)

Memory cells will be present in blood.

The memory cell will recognise the antigen and therfore produce antibodies more rapidly.

Antibodies will have a complemtnqqary shape to antigen so it will be bind and so destorying the virus before it causes damage.

This is the secondary response so primary repsone is not needed
Original post by theambitiousguru
Alveoli burst - Dec SA
Elastin permanently stretched - CG not maintained


Yeah or increased diffusion pathway


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Reply 109
Original post by EmmaHarvard
Magnification answer?


2.83ug
Original post by EmmaHarvard
Magnification answer?


2.83?
Reply 111
Original post by FlowaPowa
2.7 something


I got 2.8 micrometers, mark scheme will probably allow 2.6-2.9 or something.

Image = actual x magnification

Image was 8.4 cm

Image is 84 mm or 84,000 micrometers

84,000 = actual x 30,000 (given)

actual = 2.8
Original post by EmmaHarvard
Magnification answer?


2.7 to 2.8 micrometres.
Original post by Eeveelution
I thought the question said there was hole between the left and right ventricles, not the ventricles and the atria? I put that oxygenated and deoxygenated blood would become mixed together so some deoxygenated blood would be transported to the tissues.


Yeah it was between the two ventricles
Original post by Eeveelution
I thought the question said there was hole between the left and right ventricles, not the ventricles and the atria? I put that oxygenated and deoxygenated blood would become mixed together so some deoxygenated blood would be transported to the tissues.


Yeah whole between ventricles*
I thought it said between the atria and ventricle too??


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Original post by Eeveelution
I thought the question said there was hole between the left and right ventricles, not the ventricles and the atria? I put that oxygenated and deoxygenated blood would become mixed together so some deoxygenated blood would be transported to the tissues.

Yes that is correct
Third last questions about changing shape:

Antigen has a speficic squence of amino acids so is mutation occurs the antigen will change shape.

Memory cells produced would not recognise the new antigen, so b cells will no longer be complentary to antigen.

Vaccines are specific, one can't be made for all strains

something like that
Original post by Kira Yagami
The 3 markers the end:

(about blood transfusion)

Memory cells will be present in blood.

The memory cell will recognise the antigen and therfore produce antibodies more rapidly.

Antibodies will have a complemtnqqary shape to antigen so it will be bind and so destorying the virus before it causes damage.

This is the secondary response so primary repsone is not needed


Passive immunity Q
Original post by Kira Yagami
Third last questions about changing shape:

Antigen has a speficic squence of amino acids so is mutation occurs the antigen will change shape.

Memory cells produced would not recognise the new antigen, so b cells will no longer be complentary to antigen.

Vaccines are specific, one can't be made for all strains

something like that


Yes and I also out about when infected it would be a primary response which is slower and therefore would cause harm / symptoms

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