WJEC A2 Biology - BY4 (8th June 2015)

Predictions for 10 marker?

Reply 83

Supergirlxxxxxx

Original post by missdentist10

Does anyone know why the calvin cycle needs to occur 6 times for producing 1 molecule of glucose?

Because per turn only 1 carbon from 2xtriose phosphate is used to synthesise glucose. As glucose requires 6 carbons altogether, 6 turns is needed :smile:

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Reply 84

Asfoi

Original post by missdentist10

Does anyone know why the calvin cycle needs to occur 6 times for producing 1 molecule of glucose?

Because each time/turn, only 1 carbon of (2X) triose phosphate is used in production of glucose and the rest is used to regenerate RuBP. (ATP supplies energy for this reaction). Glucose is 6 carbon so cycle has to go around 6 times. Nice to know I'm not the only dental applicant :biggrin:

(I'm assuming you applied to dentistry based from your name)

Reply 85

missdentist10

Original post by Supergirlxxxxxx

Because per turn only 1 carbon from 2xtriose phosphate is used to synthesise glucose. As glucose requires 6 carbons altogether, 6 turns is needed :smile:

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Thanks both of you :smile:

@Asfoi yep i did :smile:

got to get the grades now :/

Reply 86

Straighthate

Original post by missdentist10

Thats BY5. Im sure its in the spec for BY5

my bad

Reply 87

OP

I cannot believe this exam is on monday!! I think it has finally hit home now... im so nervous!

Reply 88

Rosheeen

Original post by robotboy96

Same here. I feel like im revising more for history than biology.

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Yup! Guess I will have to do few more past papers for biology! Done quite a few for history but still nervous for it cause you never know what's gonna come up in the exam :frown:

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Reply 89

Supergirlxxxxxx

Does BY5 not have any January past papers?? Unit 1,2,4 all had January and June past papers apart from unit 5??

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Reply 90

OP

Okay guys I came accross this in a mark scheme today and got confused...

In the calvin cycle the production of TP from GP requires ATP as an energy source, yet it said that the regeneration of RUBP from TP needed ATP for phosphorylation of the TP not for energy... is this correct?

Reply 91

OP

Original post by Supergirlxxxxxx

Does BY5 not have any January past papers?? Unit 1,2,4 all had January and June past papers apart from unit 5??

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I dont think so...

Usually the second unit at A2 only has a summer exam (unit 2 has a winter one as people liked to resit in the winter if they did bad at AS)

Reply 92

Supergirlxxxxxx

Ohhh!! Thanks that's fine then :smile:

sat this paper last year so resitting this again! Fun times

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Reply 93

J_T_

Original post by ThePrestigeUK

Even though ive done quiet a bit of revision does any one else feel like they dont know much coming up to the exam, might just be pressure

but ive done every past paper twice and know most of the content to a decent level, yet in my head I just dont feel ready

ahhh tbh I had a chem unit 2 resit felt similar for that but smashed the exam hoping thats the case here. aswell

Wow. It sounds like you've done all you can, at this rate I'm barely going to finish all of the past papers even once!

Original post by Supergirlxxxxxx

This is from the past paper June 2011 for HB4! Kind of similar to the BY4 Paper so I thought I'd ask here :smile:

if anyone knows how to do part a) please could you attempt it and show me how it's done as the M.S here is of no use!

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Sensory neurone from flame, through dorsal root connected via a relay neurone in the grey matter to a motor neurone which exits through the ventral root and I would add a synapse next to the muscle.

Original post by Natalierm2707

Okay guys I came accross this in a mark scheme today and got confused...

In the calvin cycle the production of TP from GP requires ATP as an energy source, yet it said that the regeneration of RUBP from TP needed ATP for phosphorylation of the TP not for energy... is this correct?

Yeah, that's right.

Reply 94

OP

Original post by J_T_

Yeah, that's right.

Thanks so much !!

Reply 95

J_T_

Original post by Natalierm2707

Thanks so much !!

You could remember it fairly easily too because triose phosphate only has one phosphate but ribulose bisphosphate has two phosphates so to get from TP to RuBP another phosphate will be needed amongst other things we don't need to know about.

Reply 96

OP

Original post by J_T_

You could remember it fairly easily too because triose phosphate only has one phosphate but ribulose bisphosphate has two phosphates so to get from TP to RuBP another phosphate will be needed amongst other things we don't need to know about.

so just to clarify when going from GP to TP, GP does not undergo phosphorylation, the reaction just requires energy?

Reply 97

manjot97

Original post by Natalierm2707

so just to clarify when going from GP to TP, GP does not undergo phosphorylation, the reaction just requires energy?

GP does undergo phosphorylation, it's not the same phosphorylation as producing ATP. Just like Glucose undergoes phosphorylation with 2 ATP molecules, so does GP. That's all you need to know to be honest.

Reply 98

username1238344

13

Starting to feel so nervous! I've done every past paper that many times that I'm starting to remember what all the answers are.
Is there a table anywhere showing the net gain of ATP at each stage of respiration?

(edited 8 years ago)

Reply 99

OP