OCR 21st Century Biology - B4 B5 B6 - Unofficial Mark Scheme

😂same ia the grade boundaries just stay the same!!

Haha yes that is all we can do. What do you predict the grade boundaries to be for this paper?
I think:
A* - 43
A - 37
B - 32
C - 24
D - 17

Reply 21

tanishaevans

9

Original post by samwesttt

And for the bubble question: the bubbles of CO2 could be different volumes, plus human error

i said you might count them wrong and it could be inaccurate

Reply 22

username3167456

2

And for the second ecstacy question, im not sure you could've mentioned sample size since it never actually quoted a sample size, for all we know it could've been sufficient. I put something like there was no quoted mechanism linking the two.

Don't worry about boundaries, most people I spoke to found it a little hard. I don't think they'll go up massively than usual.. Maybe 43-46 A*

Reply 23

menna123

7

Original post by ktb786

Haha yes that is all we can do. What do you predict the grade boundaries to be for this paper?
I think:
A* - 43
A - 37
B - 32
C - 24
D - 17

Exact same😂😂😂
But I think for a b it will be 30?? Dunno why just do lol

Reply 24

tanishaevans

9

for question 17 i basically defined osmosis and then said it attempts to even out the concentration of water on both sides of the cell membrane but it cant get through which is why the concentration of mucus is higher and therefore stickier, i didn't refer to the chloride ions :frown:

can someone confirm if this is still right?

Reply 25

CandidateZero

14

Original post by samwesttt

And for the bubble question: the bubbles of CO2 could be different volumes, plus human error

I put human error! Thus raising my total (approximate) score to 52-54. Do you reckon that'll be full UMS? I need fallback UMS marks for the B7 exam which I achieved only an A in last year's paper (of course that's still great, but I'm aiming for A*).

Reply 26

username3167456

2

Original post by CandidateZero

I put human error! Thus raising my total (approximate) score to 52-54. Do you reckon that'll be full UMS? I need fallback UMS marks for the B7 exam which I achieved only an A in last year's paper (of course that's still great, but I'm aiming for A*).

Well done! I'm hoping for 53-57 I can't tell :/
I would guess 54 full UMS, but all depends on boundaries. Worst case scenario you might've got 97/98 which is still pretty good fallback!

Reply 27

Deliciate

OP

14

Yup, I'm really hoping for full UMS in this exam!!! I think even 52 will be full UMS or maybe even lower. 52 or 53 has been the highest for full UMS, hasn't it?

Reply 28

Ghostlythinking

1

Original post by Deo99

Huh I'm confused for number 4 it said when do animals respire anaerobically not human so I wrote when they are in waterlogged soils?

Plants aren't animals so it wouldn't count unfortunately

Reply 29

estherakame

Do you think I could still gain full marks if I only talked about transect in detail in the first 6 marker. I misinterpreted the question and thought they were only asking for one method smh

2 Marks

Original post by menna123

In animal cells is does not release co2
Only lactic acid.

Glucose ----> Carbon Dioxide + Ethanol

Reply 32

Dk15164

6

Original post by ahhmed123

Glucose ----> Carbon Dioxide + Ethanol

That's for yeast cells

Reply 33

lolasmithy

11

I'm confused. What was the difference between Q10 and Q14i? Were there two limiting factor graphs??

Reply 34

HAchunche

1

When you miss out the graph questions

Reply 35

Deliciate

OP

14

Original post by lolasmithy

I'm confused. What was the difference between Q10 and Q14i? Were there two limiting factor graphs??

Oh, I apologise, that was a mistake; there was only one graph question. :biggrin:

Fixed.

Reply 36

JosephCiderBwoy

16

Original post by Deliciate

Hey guys! This is the unofficial mark scheme created by @menna123 and I. Menna is awesome!!! :biggrin:

If you have any changes to make then feel free to type it and we'll edit it! :smile:

1. what is memory?- the storage (1) and retrieval of information (1)
1ii. What is the part of the brain responsible for memory?- Cerebral Cortex
2. Why would John still want to undertake the surgery? - if he does not have the surgery it can spread to the rest of his brain. The benefits of the surgery outweigh the consequence of losing some of his memory. John's perception of the risk is low because he does not mind losing his memory.
3. How does Judith remember to play the piano? First time she plays it is in short term memory; with repetition and reinforcement moves into the long term memory and this info can be retrieved/ the neural pathways form when she learns the skill; as she reinforces and repeats the skill the neuron pathways travel down more strengthened.
4. When do human cells respire anaerobically - during vigorous exercise
5. What two things are needed to make amino acids? - nitrates and glucose.
6. What do amino acids make when joined together? Proteins
7. How does water travel through the roots? Osmosis
8. Why is oil stored on top of the glucose/starch solution- so that no oxygen enters the solution as fermentation requires anaerobic respiration, presence of oxygen would mean that it would respire aerobically and fermentation would not be able to take place.
8ii. Conclusions- any valid conclusion based on the data is correct, links to respiration- At 45 degrees the rate of respiration is high due to high rate of reaction so lots of CO2 bubbles are released but would then decrease due to high temperatures denaturing the active site of the enzyme. This means that the enzyme can no longer respire anaerobically and release CO2 as the cells have been killed.
8iii. Problem with measuring CO2 bubbles- it's difficult to observe and see what qualifies as a bubble/ the bubbles of CO2 could be different volumes/ human error as not measured by a computer
8iiii. Another way to measure CO2 volume- gas syringe?
9. Ticking boxing question for respiration -
Aerobic respiration - Needs oxygen
Both aerobic and anaerobic respiration - need glucose
Anaerobic respiration - releases lactic acid
Aerobic respiration - in the mitochondria
Aerobic respiration - releases carbon dioxide
10. Graph question for limiting factor of photosynthesis- when graph flattened out. Plot the X anywhere when the graph plateaus (light is no longer increasing)
11. Six marker on dunes- transect,quadrat,identification key. Define each and explain how it would be useful.
12. Six marker on star fish- human nervous system = CNS, brain and spinal chord. Joined to body via peripheral nervous system- motor and sensory neurons. I said that the centre of the starfish was its CNS and it too has neuron pathways and receptors.
They both have receptors (light receptor in the starfish and receptors in humans)
Human nervous system has a processing centre to modify reflexes and for higher thought whereas starfish rely on simple reflexes.
Human nervous system has synapses (gaps) whereas starfish do not.
Human nervous system is made out of billions of neurons.
13. Six marker on amino acid and proteins- DNA is a double helix of paired bases a-t c-g, genetic code for production of proteins. Triplet code codes for one amino acid. Amino acids joined to make proteins etc. Different base would mean different coding of amino acid, meaning different sequence of amino acid a different/faulty protein is made. (Could refer to mRNA and ribosomes but probably not necessary in gaining 6 marks).
14. Name for when a plant grows towards light-Phototropism (positive)
14ii. Why do plants grow towards light-To increase chances of survival as they can have more light energy for photosynthesis.
15. Question on child with cystic fibrosis- (I) baby is unlikely to have cystic fibrosis, the test was negative
15i. What doctor would do with information- more genetic tests/monitor child
16. Calculations- 0.0012% and 9000
17. Question on why mucus was sticker- faulty DNA means that chloride ions (dissolved in water) cannot move from higher to lower concentration in membrane due to the fact that cystic fibrosis is a genetic disorder of the cell membranes. Meaning that the mucus stays in the region of higher concentation, further increasing the concentation of chloride ions, making mucus stickier
18. Order for serotonin concentration (not confirmed)- potentially (C) A B E D
but the order was:
1)more serotonin is released from the first neuron.
2) increase in serotonin concentration
3) more serotonin binds to next membrane
4) more impulses generated
20. What can you gather from results on ecstasy from graph- Ecstasy with psychotherapy is more effective than just psychotherapy
20ii.Question on increasing confidence in ecstasy test results- use a bigger sample and conduct over a longer period of time/ peer review and other scientists do it to make it reproducible.

Could 8iii be measure the mass of the glucose-yeast suspension before reaction, and mass after reaction?

Reply 37

JosephCiderBwoy

16

Original post by Deliciate

Hey guys! This is the unofficial mark scheme created by @menna123 and I. Menna is awesome!!! :biggrin:

If you have any changes to make then feel free to type it and we'll edit it! :smile:

1. what is memory?- the storage (1) and retrieval of information (1)
1ii. What is the part of the brain responsible for memory?- Cerebral Cortex
2. Why would John still want to undertake the surgery? - if he does not have the surgery it can spread to the rest of his brain. The benefits of the surgery outweigh the consequence of losing some of his memory. John's perception of the risk is low because he does not mind losing his memory.
3. How does Judith remember to play the piano? First time she plays it is in short term memory; with repetition and reinforcement moves into the long term memory and this info can be retrieved/ the neural pathways form when she learns the skill; as she reinforces and repeats the skill the neuron pathways travel down more strengthened.
4. When do human cells respire anaerobically - during vigorous exercise
5. What two things are needed to make amino acids? - nitrates and glucose.
6. What do amino acids make when joined together? Proteins
7. How does water travel through the roots? Osmosis
8. Why is oil stored on top of the glucose/starch solution- so that no oxygen enters the solution as fermentation requires anaerobic respiration, presence of oxygen would mean that it would respire aerobically and fermentation would not be able to take place.
8ii. Conclusions- any valid conclusion based on the data is correct, links to respiration- At 45 degrees the rate of respiration is high due to high rate of reaction so lots of CO2 bubbles are released but would then decrease due to high temperatures denaturing the active site of the enzyme. This means that the enzyme can no longer respire anaerobically and release CO2 as the cells have been killed.
8iii. Problem with measuring CO2 bubbles- it's difficult to observe and see what qualifies as a bubble/ the bubbles of CO2 could be different volumes/ human error as not measured by a computer
8iiii. Another way to measure CO2 volume- gas syringe?
9. Ticking boxing question for respiration -
Aerobic respiration - Needs oxygen
Both aerobic and anaerobic respiration - need glucose
Anaerobic respiration - releases lactic acid
Aerobic respiration - in the mitochondria
Aerobic respiration - releases carbon dioxide
10. Graph question for limiting factor of photosynthesis- when graph flattened out. Plot the X anywhere when the graph plateaus (light is no longer increasing)
11. Six marker on dunes- transect,quadrat,identification key. Define each and explain how it would be useful.
12. Six marker on star fish- human nervous system = CNS, brain and spinal chord. Joined to body via peripheral nervous system- motor and sensory neurons. I said that the centre of the starfish was its CNS and it too has neuron pathways and receptors.
They both have receptors (light receptor in the starfish and receptors in humans)
Human nervous system has a processing centre to modify reflexes and for higher thought whereas starfish rely on simple reflexes.
Human nervous system has synapses (gaps) whereas starfish do not.
Human nervous system is made out of billions of neurons.
13. Six marker on amino acid and proteins- DNA is a double helix of paired bases a-t c-g, genetic code for production of proteins. Triplet code codes for one amino acid. Amino acids joined to make proteins etc. Different base would mean different coding of amino acid, meaning different sequence of amino acid a different/faulty protein is made. (Could refer to mRNA and ribosomes but probably not necessary in gaining 6 marks).
14. Name for when a plant grows towards light-Phototropism (positive)
14ii. Why do plants grow towards light-To increase chances of survival as they can have more light energy for photosynthesis.
15. Question on child with cystic fibrosis- (I) baby is unlikely to have cystic fibrosis, the test was negative
15i. What doctor would do with information- more genetic tests/monitor child
16. Calculations- 0.0012% and 9000
17. Question on why mucus was sticker- faulty DNA means that chloride ions (dissolved in water) cannot move from higher to lower concentration in membrane due to the fact that cystic fibrosis is a genetic disorder of the cell membranes. Meaning that the mucus stays in the region of higher concentation, further increasing the concentation of chloride ions, making mucus stickier
18. Order for serotonin concentration (not confirmed)- potentially (C) A B E D
but the order was:
1)more serotonin is released from the first neuron.
2) increase in serotonin concentration
3) more serotonin binds to next membrane
4) more impulses generated
20. What can you gather from results on ecstasy from graph- Ecstasy with psychotherapy is more effective than just psychotherapy
20ii.Question on increasing confidence in ecstasy test results- use a bigger sample and conduct over a longer period of time/ peer review and other scientists do it to make it reproducible.

With the 6 marker about proteins, I described DNA being in a double helix, with phosphate backbones and base pairs as nucleotides. I then went on to describe protein synthesis, and said if the bases were in the wrong order (hence mutation) then the wrong amino acid would confirm the faulty protein being made - something like that? Plus I used the scientific vocabulary, so a mark might be there as well for right terminology

Reply 38

ktb786

2

Original post by JosephCiderBwoy

With the 6 marker about proteins, I described DNA being in a double helix, with phosphate backbones and base pairs as nucleotides. I then went on to describe protein synthesis, and said if the bases were in the wrong order (hence mutation) then the wrong amino acid would confirm the faulty protein being made - something like that? Plus I used the scientific vocabulary, so a mark might be there as well for right terminology

That is perfect. I also talked about nucleotide units and a sugar, phosphate and basetc. The question was not about the process of protien synthesis. It was about how the order of bases in a gene might code for a mutation, which links to the 'translation' part of protien synthesis. Also, for the nervous system starfish question, I stupidly talked about a human nerve cell and the starfish nervous syste and began linking dendrites, which detect changes in stimuli, to the radical nerve etc. I misread the question. Because I spoke about specifically the human nerve cell and linked this to the functions on the starfish would I be able to pick up a couple of marks? I didn't go into detail with CNS and PNS because of misreading the question.