Year 12s: what will be the first way you research your future options? >>

Edexcel Biology (Unofficial) B2 Mark Scheme.

Scroll to see replies

For the fossil question, I wrote about how some mammals in group A became extinct, and some mammals didn't fossilise (soft body tissues, and decomposition) and that caused the population to go Down. However, looking at this thread is making me panic because I never wrote about natural selection :frown:

Don't panic! I'm sure that your answer is very relevant and honestly, it's not like we're 100% sure about all these answers. xP

Reply 61

bue34 c

Original post by Regret786

My answers that I think are right:

For minimum number of bases, I got 630*3=1890

For the fossil groups, I got D as extinct. A's decrease in estimated population between 10-7m years ago was caused by:

•

C evolving to prey on A

•

Dead A's did not fossilize

•

Not all of A's fossils were found

For the mutation one, where a base pair is changed, I got that the protein is changed because a different amino acid would be made in the polypeptide chain. This causes it to fold differently, and make a misshapen protein.

For the Meiosis - Mitosis difference one, I got it as:

•

Meiosis produces genetically different daughter cells, Mitosis produces identical

•

Meiosis produces 1 pair of chromosomes in the daughter cell, Mitosis produces 2 pairs

•

Meiosis produces 4 daughter cells, Mitosis produces 2. There are more points that I didn't write

For the coronary artery one, I got the following:

•

The narrower artery is on the left ventricle. By it being narrow, the muscles receive less oxygen and glucose, and will be worker weaker.

•

The ventricle will not be able to contract as strongly as before, causing less heart pressure

•

This will cause a weaker heart, and decrease the cardiac output

•

This means that the less blood will be going throughout the body, meaning more anaerobic respiration when exercising

•

There will be more lactic acid left over

•

There will be a longer excess post-exercise oxygen consumption (EPOC) (didn't actually write it, just realized it now)

For the recognizing the blood vessel on the labelled diagram, I'm pretty sure it was the pulmonary vein

Will edit it as it comes to mind.

yh pulmonary vein then the next one was about how does deoxygenated blood get into the lungs i wrote it enters via vena cava then goes past tricuspid valves and goes to right atrium then to lungs via pulmonary artery going past semi lunar valves to get oxygenated via alveoli

Reply 62

bue34 c

what did you guys write for the pentadactyl limb structure on? why was it two marks? I wrote its a limb with 5 digits and thats it

Reply 63

ARK_REVISES

Original post by keepyourapology

Don't panic! I'm sure that your answer is very relevant and honestly, it's not like we're 100% sure about all these answers. xP

I wrote about more oxygen increades by photosynthesis,which caused extinction of animals that couldn't tolerate it. Is that right??

Reply 64

Moon.idk

For the number of bases i did 630 x 3 = 1890 bases
Idk if that is right as some people did 630 / 3 = 210

Reply 65

glowanti

Original post by bue34 c

what did you guys write for the pentadactyl limb structure on? why was it two marks? I wrote its a limb with 5 digits and thats it

Yeah I was confused as to why it was 2 marks. I said about the limb with 5 digits then started saying what it would be used for & they can be as an arm or a wing and are usually followed by an ulna, radius and humerus which can be fused together looool I was just writing anything I could think of

Reply 66

bue34 c

Original post by Moon.idk

For the number of bases i did 630 x 3 = 1890 bases
Idk if that is right as some people did 630 / 3 = 210

Yh ur right i think

Reply 67

glowanti

Original post by Moon.idk

For the number of bases i did 630 x 3 = 1890 bases
Idk if that is right as some people did 630 / 3 = 210

What was this question even asking for? The maximum number of bases in 630 amino acids?

Reply 68

bue34 c

Original post by caitlinford3

What was this question even asking for? The maximum number of bases in 630 amino acids?

Yh i think it said how many bases in a gene make up 630 amino acids or something like that

Reply 69

username2174765

Original post by caitlinford3

What was this question even asking for? The maximum number of bases in 630 amino acids?

minimum

Reply 70

glowanti

Original post by chrlhyms

minimum

Original post by bue34 c

Yh i think it said how many bases in a gene make up 630 amino acids or something like that

oh right. So annoying losing stupid marks :frown:

Reply 71

shania.d.f

A codon has three bases and one codon makes up one amino acid. So, it would make sense to do 630*3. Honestly, I think they just said minimum to confuse students.

Posted from TSR Mobile

Reply 72

ARK_REVISES

Hey guys my teacher told me that p1 was the hardest from core so that means p2 and p3 are going to be fine. And because p2 is easy and we had juz done the b2 was easy too means there is a higher chance of c2 being harder. So we are left out with b3 and c3. He then said cos c2 is going to be hard c3 is going to be easier. For biology we are going to sit b3 two weeks later that is going to be the hardest.

So by summarizing again:
C2=hard from chemistry
B3=hard from biology
P1=hard from physics.

But still dont underestimate it can sometimes be harder and u cant be
100% sure if my teachers are right. Dont leave out anything that you haven't done and think you can ace it without revising..... So dont entirely listen to me. G'LUCK!!!!

Reply 73

bue34 c

what did you guys write for the question that said to explain the differences in concentration of carbon dioxide between tube ?,?,? which i think were with sucrose

Reply 74

niichola.

Original post by Regret786

•

C evolving to prey on A

•

Dead A's did not fossilize

•

Not all of A's fossils were found

•

Meiosis produces genetically different daughter cells, Mitosis produces identical

•

Meiosis produces 1 pair of chromosomes in the daughter cell, Mitosis produces 2 pairs

•

Meiosis produces 4 daughter cells, Mitosis produces 2. There are more points that I didn't write

For the coronary artery one, I got the following:

•

The narrower artery is on the left ventricle. By it being narrow, the muscles receive less oxygen and glucose, and will be worker weaker.

•

The ventricle will not be able to contract as strongly as before, causing less heart pressure

•

This will cause a weaker heart, and decrease the cardiac output

•

This means that the less blood will be going throughout the body, meaning more anaerobic respiration when exercising

•

There will be more lactic acid left over

•

There will be a longer excess post-exercise oxygen consumption (EPOC) (didn't actually write it, just realized it now)

For the recognizing the blood vessel on the labelled diagram, I'm pretty sure it was the pulmonary vein

For the Watson and Crick one, I wrote that they used the pictures taken by Wilkins and Franklin to produce the double-helix model

For the peas one, I wrote that the detergent will be alkaline, making the nuclei break up. The mashing is to increase the surface area as well as breaking the other skin of the peas

For how the de-oxygenated blood gets to the lungs from the right atrium, I wrote the following:

•

The atrium contracts, forcing the blood into the right ventricle

•

The ventricle contracts when full, and pushes the blood through the pulmonary artery

•

The artery splits up into capillaries and gets oxygenated

For the pentadactyl one, I wrote the following:

•

The mammals have a humerus;

•

an ulna

•

wrist bones

•

and 5 fingers/digits. There is more to write, but that should be enough. The other answers are:

•

a radius

•

The wrist bones are called carpals

For the embryo specialization one, I wrote that the stem cells made in the embryo specialize into whatever the embryo needs to grow. Didn't really get this one, I think.

For the true or false statement multiple choice question, I selected that only A was true.

I'll avoid repeating things the OP has updated. IDM if the OP uses these answers.

Will edit it as it comes to mind.

You got the amino acid one incorrect. You were meant to divide 630/3 = 210