Edexcel AS Biology - 6B101 + 6B102 - Unit 1 and Unit 2 Exam Discussion Thread

True re the risks, but you can drop those marks and still score 65-70 which is plenty.

Which part on the fatty acids confused you?

Its not actually the content on that question, its the actual question I guess aha, about the calculatio and why theres differences in the concertrations of saturated and unsaturated fatty acids.

Also, on this paper have you see question 1(a) (ii) On the max number of amino acids coded for by a molecule of mRNA that is 600 mononucleosis long is - so confusing?

Reply 381

DK 96

2

Why do the elastic fibres in Aorta stretch and then recoil?

Reply 382

redbuthotter

17

Original post by redtoffe

Its not actually the content on that question, its the actual question I guess aha, about the calculatio and why theres differences in the concertrations of saturated and unsaturated fatty acids.

Also, on this paper have you see question 1(a) (ii) On the max number of amino acids coded for by a molecule of mRNA that is 600 mononucleosis long is - so confusing?

3 Bases to 1 amino, so divide 3 to get 200?

Reply 383

redtoffe

1

Original post by MATTTT

Hi can i get them as well?

Can I get these too? aha

Reply 384

redbuthotter

17

Original post by DK 96

Why do the elastic fibres in Aorta stretch and then recoil?

To cope with changes in pressure when the heart contracts and relaxes.

Reply 385

redtoffe

1

Original post by redbuthotter

3 Bases to 1 amino, so divide 3 to get 200?

Oh ahaha I don't see why I didn't get this before, thanks.

Reply 386

.JC.

14

Original post by Feraligatr

Yep, on diffusion and gaseous exchange. Pretty much GCSE stuff though, large surface area due to small size and many alvoeli. Short diffusion pathway so more efficient. Concentration gradient maintained as oxygenated blood is taken away and deoxygenated blood comes along.

What's the exact question though?

Thanks, all comes flooding back ahaha.

'Describe and explain how the lungs of a mammal are adapted for rapid gasexchange.' [5 marks]

Reply 387

DK 96

2

Original post by redbuthotter

To cope with changes in pressure when the heart contracts and relaxes.

Yep,so they stretch to lower the blood pressure
- recoil to return back to shape ?

but do we need to know more than that ? for example "Explain why elastic fibres stretch and then recoil?" (3 marks)

Reply 388

Feraligatr

OP

20

Original post by .JC.

Thanks, all comes flooding back ahaha.

'Describe and explain how the lungs of a mammal are adapted for rapid gasexchange.' [5 marks]

Yeah, pretty much what I said previously. You should get 5 marks if you mention all that.. :smile:

Reply 389

redbuthotter

17

Original post by DK 96

Yep,so they stretch to lower the blood pressure
- recoil to return back to shape ?

but do we need to know more than that ? for example "Explain why elastic fibres stretch and then recoil?" (3 marks)

That should get the marks. Although on semantics - I think they stretch due to the high blood pressure during systole, like blowing into a balloon it stretches, rather than it consciously stretches to lower blood pressure if that makes sense.

Reply 390

Maronite

4

Original post by DK 96

Yep,so they stretch to lower the blood pressure
- recoil to return back to shape ?

but do we need to know more than that ? for example "Explain why elastic fibres stretch and then recoil?" (3 marks)

Isn't that so a pulse is created?

Reply 391

N.Choi

2

What is the difference between the lock and key theory and the induced fit theory?

Reply 392

DK 96

2

Original post by Maronite

Isn't that so a pulse is created?

Not sure, but I think pulse concerns the whole cardiac cycle

Reply 393

lizmoo0721

13

Original post by N.Choi

What is the difference between the lock and key theory and the induced fit theory?

Lock and key = more specific, enzyme doesn't change shape.
Induced fit = active site changes slightly to fit the substrate.

Reply 394

DK 96

2

What are features of the circulatory system and how are they adapted to overcome limitations of diffusion?I'm a bit confused about respiratory and circulatory system

(edited 8 years ago)

Reply 395

Feraligatr

OP

20

STUDY GROUP FOR BIO

http://www.thestudentroom.co.uk/g/st...cel_as_biology

Reply 396

barbiex

2

can someone explain the steps in gene therapy and like important points we may need to know for it?

Reply 397

N.Choi

2

Original post by lizmoo0721

Lock and key = more specific, enzyme doesn't change shape.
Induced fit = active site changes slightly to fit the substrate.

How does the active site change it's shape??

Reply 398

Neuth

19

Would anybody be interested in going through the specification, point by point, to make a list of answers?

I'm not sure if here would be the best place for it, but I'd be happy to make a new thread or skype group or similar if people liked the idea. It could then be posted in it's entirety on here, and made into a word document etc.

I just think it is the best way to convince yourself you know everything you need to, and also to highlight gaps in your knowledge :yep: