OCR A-Level Biology Paper 3 17th June 2019 - Unified Biology [Unofficial Markscheme]

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It said genes so I talked about regulatory and structural coding for specific antibodies 😂

Also am I the only one who couldnt think of anything for the 6 marker on B and T cells. What were they asking for when they talked about genetic factors? Surely that has nothing to do with immunisation/immune response

Reply 81

Agglutination26

Original post by shohaib712

What were you supposed to put for the fructose question? Its was so hard. I wrote that it produced a net ATP of 4 instead of 2

It said that lactate prevented an enzyme to convert glucose to triose phosphate. It was in anaerobic conditions so lactate was produced. Fructose is used cause it’s not inhibited to turn into triose phosphate to form pyruvate in glycolysis thus respiration continues.

Reply 82

shcrazy_

I was running out of time so couldn’t answer it properly, but I briefly spoke about mutations and allels, coding for different proteins therefore different antibody structures etc,

Original post by shohaib712

For the 6 marker on immunity. I believe you are supposed to talk about natural and artificial, active and passive immunity. So for example natural, passive immunity is only determined by genes and leads to individual being immune to disease due to inheritance of antibodies directly from mother via breastfeeding. Artificial passive immunity is determined only be environment. Artificial active immunity (vaccines) is determined by both environmental and genetic factors. As environmental cuz you are receiving it not naturally. But genetic due to body natural response to produce memory cells.

Reply 83

Elliefish

I'm pretty sure it was spores and vectors

Original post by b987535

are you sure? i put vectors and gradients???
please tell me im not dumb....

Reply 84

Ameliakkmm

I’m sure you just had to say that lactate doesn’t inhibit the conversation of fructose into triose phosphate?

Original post by Elliefggj

I put about it being hydrolysed because a glucose+ a glucose= fructose and glucose is a respiratory substrate, this was a complete guess

Reply 85

HaroonSharif

It was an air space and not a vacuole because the air space didn't have an defined / set membrane around it and it wasnt well structured as vacuoles usually are. So must be an air space

Reply 86

sophiexxacorn

Yeah same

Original post by Agglutination26

Reply 87

lionike123

https://www.sciencephoto.com/media/918418/view/plant-cell-tem
Here is the answer. Clearly says vacuoles and nucelus.

Original post by HaroonSharif

It was an air space and not a vacuole because the air space didn't have an defined / set membrane around it and it wasnt well structured as vacuoles usually are. So must be an air space

Reply 88

Elliefish

I said this too about enzymes and respiration! Thank goodness I'm not the only one!

Original post by aquaticflames

this is correct. I'm so annoyed I didn't think of this. basically the enzymes for respiration slow down, less heat is generated from respiration and therefore the body cools further. oh well! that was a tough one

Reply 89

Ameliakkmm

I thought this and there was quite a lot of them as well as the fact it’s a pondweed and needs lots of air spaces to store oxygen

Original post by HaroonSharif

It was an air space and not a vacuole because the air space didn't have an defined / set membrane around it and it wasnt well structured as vacuoles usually are. So must be an air space

Reply 90

not_XIX_forever

Do you think boundaries will be higher or lower compared to previous years?

Reply 91

nicholasflee

yeah but plant cells also have large vacuoles to store water and waste products, both air space and vacuole should be acceptable

Original post by Ameliakkmm

I thought this and there was quite a lot of them as well as the fact it’s a pondweed and needs lots of air spaces to store oxygen

Reply 92

Arice38366

This year papers are similar in difficulty level to last year so i couldn't say that it was hard but the content is uniquely bull**** compared to any past exams and papers i did even the 2017 or 2018. Its 20% of what we learned for god sake 2 years of bio freaking heavy af content than any other subs could be.

Reply 93

Stormragexox

Original post by archibald300

Do you think boundaries will be higher or lower compared to previous years?

hoping it is lower cuz litterally no full on photsynthisis no muscle contraction and no inhertence came up

(and i felt so lost the whole paper cuz the questions were form topics i barely look at)

(edited 4 years ago)

Reply 94

kKingg

Original post by archibald300

Do you think boundaries will be higher or lower compared to previous years?

Hope boundaries will be lower because there was less biological explanations and more general application questions which tends to catch people out

Reply 95

Icryscience

My thought was psychrophile but not entirely sure.

Original post by nonoui

What's the word for a cold adapted biological molecule?

Reply 96

Deliciate

think it'll be slightly lower or same as last year

Reply 97

PureDTJ

I did this

Original post by letapyikut

For the radius question do you not have to times by 2 to get the diameter

Reply 98

patriciaanne

Original post by shohaib712

What were you supposed to put for the fructose question? Its was so hard. I wrote that it produced a net ATP of 4 instead of 2

I wrote something about how using fructose allowed it to regenerate triose phosphate, meaning substrate level phosphorylation via glycolysis could continue, so ATP can still be produced without the need for oxygen as glycolysis is anaerobic