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RESIT Edexcel Biology Unit 1 - 26th May (6BI01)

Not seen a thread specifically for those resitting, so here is one!

How is everyone feeling?

What do you think might come up?

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Reply 1

kosmooos

I was resisting. How was the exam? Is there unofficial mark scheme already?

Reply 2

saira123x

Is there an unofficial mark scheme?

Reply 3

melanin101

It was OK. I kind of ran out of time.

It looks like most people did the new spec paper (obviously). It'll probably take longer for us lots to get a mark scheme.

Reply 4

chemica

Original post by melanin101

It was OK. I kind of ran out of time.

It looks like most people did the new spec paper (obviously). It'll probably take longer for us lots to get a mark scheme.

does anyone remember the second to last question ? On Sickle Cell anaemia ?, I ran out of time as well :'(

Reply 5

splog23

The one about West Africans?

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Reply 6

kosmooos

I wrote that AA life expectancy is lower than Aa because Aa have protection against infection by insect. But AA is higher than aa because aa have anemia

Reply 7

melanin101

Original post by chemica

does anyone remember the second to last question ? On Sickle Cell anaemia ?, I ran out of time as well :'(

It was something like: "DIscuss the life expectancy of people who have an Aa (heterozygous) genotype". I have bad memory :frown:

----

That Fick's law question (gas exchange in mammals) question hurt my hand.

Bare bones of my answer:
- Intercostal + Diaphragm muscles contract and relax forcing air in and out therefore removing CO2 and taking in more O2. This keeps the concentration gradient steep by continually supplying more O2 and expelling CO2.
- The surface area of the alveoli is massive. Very large respiratory surface therefore lots of area for gas exchange to happen. This increases rate of diffusion.
- Diffusion pathway is extremely short as single walled alveoli are in very close vicinity to walls of single celled capillaries. Short pathway for CO2 and O2 to diffuse through therefore increasing rate of diffusion.
- Details on lungs, air goes through trachea -> bronchi -> bronchioles -> millions and millions of alveoli with many bulbous sacs.

I think the key to this question was talking about how our lungs maximise rate of diffusion. In this case, keeping the top of the fraction (conc. gradient & surface area) large and the bottom of the fraction (diffusion pathway) small.

--

What did you guys write on the effect of boiling on Vitamin C?

(edited 7 years ago)

Reply 8

kosmooos

Original post by chemica

does anyone remember the second to last question ? On Sickle Cell anaemia ?, I ran out of time as well :'(

I wrote that AA life expectancy is lower than Aa because Aa have protection against infection by insect. But AA is higher than aa because aa have anemia

Reply 9

kosmooos

Original post by melanin101

It was something like: "DIscuss the life expectancy of people who have an Aa (heterozygous) genotype". I have bad memory :frown:

I wrote it hydrolyses ester bonds in vitamin C by using molecule of water

Reply 10

melanin101

Original post by kosmooos

I wrote it hydrolyses ester bonds in vitamin C by using molecule of water

I had no idea that vitamin C had ester bonds :frown:

I just wrote that bonds broke due to high temp lol

Reply 11

atherosclerosis

What do you think the grade boundaries will be like: the ones I found most difficult was explaining why it was a dominant disorder, why there was less vitamin c loss from boiling than from cold water to boiling

Reply 12

splog23

That's the gist of it, yeah.

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Reply 13

kosmooos

Original post by melanin101

I had no idea that vitamin C had ester bonds :frown:

I just wrote that bonds broke due to high temp lol

I have seen it in one past paper from chemistry edexcel A2

Reply 14

ABeingOnEarth

What probability did you guys get for the genetic diagram question?

Reply 15

splog23

Original post by kosmooos

I wrote it hydrolyses ester bonds in vitamin C by using molecule of water

I said that boiling would break down the cell surface membrane (proteins denaturing and so forth) and so vitamin C could move out of it

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Reply 16

kosmooos

I labeled the pulmonary vein wrong way around and in the last minute I wanted to change it but my paper was taken at that moment

Reply 17

melanin101

Original post by ABeingOnEarth

What probability did you guys get for the genetic diagram question?

50%

Reply 18

Silverstars123

Original post by kosmooos

I wrote that AA life expectancy is lower than Aa because Aa have protection against infection by insect. But AA is higher than aa because aa have anemia

hmm i think i answered that wrong, i wrote AA is higher becuase they have the normal alleles and Aa has the same as AA because the anemia is not expressed in the phenotype only in the genotype

Reply 19

kosmooos

Original post by atherosclerosis

I think the paper was repetition of past papers
I also had the same difficulties. I did not explain properly why dominant disorder, I just said dominant allele always expressed in phenotype, unaffected must be recessive.
When asking about boiling and cold, I said that boiling denatures enzyme and with cold less kinetic energy, so enzymes work slower. I am not sure about this question. I just wrote it in the end when I read that some enzyme was involved in oxidizing vitamin C in the beginning of the question