AQA A-level Biology 7402 - Paper 3 - 17th June 2019 Unofficial Markscheme

Original post by KVJ

What did you guys get for the selection of patients one (who were all female and you couldn’t put their gender or general health)?

I put level of physical activity and whether they were already on medication for arthiritis

Reply 42

Original post by wajopdsjf

Q1.
Ultrafiltration describe process...
Tick Box
Thicker medulla

Q2)
Heart dissection
LEFT atroventricular valve
LEFT ventricle
Precautions...
Scapel (sharp etc)
Gloves (sanitory purposes etc)
Uni directional flow
Describe valves opening and closing
Describe pressure changes and flow of blood

Q3)
Samples of water
Make up KNOWN solutions of water
Measure absorbance of each sample... use colorimeter
Calibration Curve
Use graph to determine cloudiness

Q4)
Caffeine --> Why it increase HR
Mention increase nerve impuleses to medulla oblangata
Increase nerve impulse frequency through sympathetic NS
More Noradrenaline released
More SAN/AVN excitation
More contraction of cardiac muscle

Control:
NO caffeine but sugar
Effect: See whether sugar actually has an affect on increasing HR

Q5)
Anti cancer drug (3marks)
Trexall has a similiar hape/structure to folic acid
Acts as an COMPETITIVE inhibitor
Less E-S complexes formed
Less nucleotides available for DNA replication
Less division by mitosis

Age of cancer cell 11.6

STARFISH question...
Choice chamber ... two things kept the same so that they show normal behaviour
PH
Temperature
Coral reef etc
Explain whether either light can be used(3 marks)
Comment on BOTH SD
Effect on each

Maths questions...
17.4
Volume of blood (70-78 range)
Sphere question
Hours for starfish... 3 Hours
30030mm^3

Essay (25marks)
Bonding and bonds in organisms
DNA and its use in tech

Help me with questions @evilhomer

Hey mate good job thanks, and btw the volume is 32023 not 30030 I’ve checked

Reply 43

I got age as 4.8 rather than 11.6, I think 11.6 was the log number of cells or something and you had to read across to the X axis which had the age. I don't remember but I don't think the x axis went past 10? (may be wrong)

Original post by wajopdsjf

Q1.
Ultrafiltration describe process...
Tick Box
Thicker medulla

Q2)
Heart dissection
LEFT atroventricular valve
LEFT ventricle
Precautions...
Scapel (sharp etc)
Gloves (sanitory purposes etc)
Uni directional flow
Describe valves opening and closing
Describe pressure changes and flow of blood

Q3)
Samples of water
Make up KNOWN solutions of water
Measure absorbance of each sample... use colorimeter
Calibration Curve
Use graph to determine cloudiness

Q4)
Caffeine --> Why it increase HR
Mention increase nerve impuleses to medulla oblangata
Increase nerve impulse frequency through sympathetic NS
More Noradrenaline released
More SAN/AVN excitation
More contraction of cardiac muscle

Control:
NO caffeine but sugar
Effect: See whether sugar actually has an affect on increasing HR

Q5)
Anti cancer drug (3marks)
Trexall has a similiar hape/structure to folic acid
Acts as an COMPETITIVE inhibitor
Less E-S complexes formed
Less nucleotides available for DNA replication
Less division by mitosis

Age of cancer cell 11.6

STARFISH question...
Choice chamber ... two things kept the same so that they show normal behaviour
PH
Temperature
Coral reef etc
Explain whether either light can be used(3 marks)
Comment on BOTH SD
Effect on each

Maths questions...
17.4
Volume of blood (70-78 range)
Sphere question
Hours for starfish... 3 Hours
30030mm^3

Essay (25marks)
Bonding and bonds in organisms
DNA and its use in tech

Help me with questions @evilhomer

Reply 44

Ok I've added up my unofficial markscheme and I have 50 marks noted out of the 53, so still looking for 3 more marks

Here's stuff you missed bro:

nutrient cycle on q3 2 marks
factors other than age gender on q5 2 marks
comment on vo2/cs graph and evaluate conclusion of that retarded graph both 3 marks each so 6 marks
then 2 marker for mitrochondrial rna or something, was the last question

I think there are a few more marks for that mitrochondria question but I cant rmemeber them lemme know if you remember

Edit got them:

1 mark for mutation - substitution
2 marks for comment on the effect of VO2/CS question after 8 weeks of exercise

So that's all 53 i think unless I've duplicated 1-2 marks, add them to the unofficial mark scheme when you can

(edited 4 years ago)

Reply 45

Aachrystal

4

Original post by CopyThat

**** i thought it was the semi-lunar valve.. it looked quite high up

It was the Semi-lunar valve according to my teacher dont worry! I put semi lunar too

Reply 46

blueoreo

3

Original post by Khushi.S

I think I got like 4.8 years for one of the questions

same! tumour growth one i think c:

Reply 47

em.parr1

1

the real question is if bonding is the same as binding because I didn't do that essay on bonding just incase it was only one like hydrogen and ionic bonding

Reply 48

Original post by em.parr1

the real question is if bonding is the same as binding because I didn't do that essay on bonding just incase it was only one like hydrogen and ionic bonding

I don’t really know because you do technically need bonds for stuff to bind, I think because the question was so vague, they’ll have to account for bimding? Although that would mean that basically every single topic is present in the mark scheme
A lot of people did put stuff like muscle contraction down so they may include it

Reply 49

alevelsishard!!

6

What did everyone get for that medulla question.

Reply 50

CopyThat

12

That was annoying.. i kinda winged that one and said the water potential is more negative inside the medulla therefore water diffuses out of the collecting duct via osmosis forming high concentrate urine. Probs wrong :smile:

Original post by alevelsishard!!

What did everyone get for that medulla question.

(edited 4 years ago)

Reply 51

CopyThat

12

Also for all the evaluate ones i started talking about stats tests etc.. like i mentioned that a student t-test should be carried out when comparing those means ( i cant remember the question) does anyone know if i was along the right lines?

Reply 52

Original post by alevelsishard!!

What did everyone get for that medulla question.

I said more of the loop of Henle and the Duct are in contact with the medulla and so, more water can diffuse into medulla via osmosis and this made the filtrate more concentrated, I also said that the increase was linear but doubt that’s a mark

Reply 53

iyanu21

3

I swear on the caffeine question it asked for the effect after 60 minutes
At which point the heart rate was decreasing not increasing ?

Reply 54

Original post by iyanu21

I swear on the caffeine question it asked for the effect after 60 minutes
At which point the heart rate was decreasing not increasing ?

It asked what caused the effect "at" 60 minutes (definitely never said "after") which I took to mean what happened for it to get it to that point, i.e increase of heart rate, but tbh it could go either way so I'm not sure either.

Reply 55

s171958

4

Hi for the question on cloudiness all I wrote was take sample from each river and measure absorbances using colorimter. How much would this be worth if anything

Reply 56