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

What did everyone get for the percentage change question?

Reply 41

Original post by Darcy-Darling

What did everyone get for the percentage change question?

22.2%

Reply 42

what did people put for "explain why the red blood cell burst or increased in volume, when placed in a distilled water?"

Reply 43

kdizzle97

Original post by Darcy-Darling

What did everyone get for the percentage change question?

I think I got 74.5%
Probably did it wrong though

(edited 7 years ago)

Reply 44

Excuse Me!

Original post by kosmooos

How about why the study may not show link? (the question after blood clot, 5 last one)
Is it about something like:
Results are not valid because are variables need considering like age and gender. We don't know sample size
???

- genetic predisposition
- factors not controlled ie age gender

thats what i put

sample size sounds like a good point

Reply 45

Original post by chemica

what did people put for "explain why the red blood cell burst or increased in volume, when placed in a distilled water?"

I spoke about the osmotic effect. Water moves in causing them to swell/lyse x

Reply 46

Original post by Excuse Me!

This may help jog memories for someone to piece together a mark scheme or to discuss answers, not sure if ive remembered everything or if order is correct

1) DNA protein synthesis, differences in DNA and RNA

2) vitamin c cabbage core practical, discuss difference in vitamin c content due to boiling

3) calculate percentage change, lipids, draw how a triglyceride is made, how are amylose and glycogen different, how are they adapted for function

4) Pedigree diagram to show that moyamoya is caused by dominant allele, probability of child from persons 3 and 4

5) phospholipid bilayer transport multiple choice,

6) cholesterol study in different countries, give dietary advice from table

7) Cholesterol levels, blood clot fill the gap, how could this lead to a heat attack

8) draw a line for the pulmonary artery, difference between capillary and vein, diffusion of CO2 and O2 comparison, explain how mammals transport gasses

9) different genotypes and how they affect life expectancy, how different amino acid affects haemoglobin structure

The ones I can muster up the effort to write answers to are:
1) should be the diagram with the phosphate group and Base joined to the sugar either side of the central top molecule.
RNA transcription would be B because there was an error during coding
8 amino acids, 6 tRNA

3)% change was about 74%,
Diagram should include 3 fatty acid molecules joining to one glycerol molecule via a condensation reaction , with 3 H2O being produced and an ester bond forming. All labelled
Amylose has no side branches, glycogen does
Both Amylose and glycogen are insoluble and have little osmotic effect, coiled structure makes them compact, glycogen has side chains that mean it can be rapidly hydrolysed for easy access to energy

4) 50% likelihood, accurate punnett square drawn

5)osmosis is passive, can't remember the other Mc qs

7) platelets, prothrombin, blood clot reduces vessel lumen, increases blood pressure, can break off and partially/fully block blood+ oxygen supply to the heart, causing cell death and heart attack

8) the question was Pulmonary Vein branch, any branch on the bottom vessel would be correct,
Capillaries have a one cell thick endothelium, veins have valves
O2 conc gradient was greater so rate of diffusion is greater (use figures)
Talk about everything given in the Q, large surface area of alveoli, short distance because capillary wall and alveolus wall are both thin, high conc. Gradient, all combine to make a large rate of diffusion

9)AA means no sickle cell anaemia but no protection against parasite
Aa is longer life expectancy because they have enough normal cells to avoid severe anaemia and parasite destroys mutated cells before it can reproduce, so malaria resistance as well
Change in amino acid means change in primary, secondary, tertiary and quaternary structure, different folding, iron group may not be able to bind properly.

Hope this helps :smile:

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Reply 47

gameofthrones1

Original post by kosmooos

yeah that's what I put, there is no guarantee that diet will cause CVD as there are other factors that can influence CVD such as obesity or high blood pressure, or factors such as age and gender

Reply 48

Original post by gameofthrones1

yeah that's what I put, there is no guarantee that diet will cause CVD as there are other factors that can influence CVD such as obesity or high blood pressure, or factors such as age and gender

This, and also countries may consume different quantities of food (eg a countries people eating lots of healthy food would still get CVD because overweight) and also some cultures place importance on being healthy, exercise etc

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Reply 49

kosmooos

Original post by Excuse Me!

This may help jog memories for someone to piece together a mark scheme or to discuss answers, not sure if ive remembered everything or if order is correct

1) DNA protein synthesis, differences in DNA and RNA
Number of amino acids: 6Differences DNA contain deoxyribose, RNA contains ribose DNA contains base thymine, RNA uracil Third mark ( probably lost) DNA is double helix, mRNA is one strand and tRNA is part double stranded. DNA only in nucleus. RNA is in nucleus (mRNA) and cytoplasm (mRNA and tRNA)

2) vitamin c cabbage core practical, discuss difference in vitamin c content due to boiling
Use of cabbage juice. Titrating juice into DCPIP. Colour change from blue to colourless when juice added. Use of calibration curve to determine vitamin C concentration. Controlled variable is temperature. Repeat the experiment.

3) calculate percentage change, lipids, draw how a triglyceride is made, how are amylose and glycogen different, how are they adapted for function
Glycerol + 3fatty acids = triglyceride + water
Amylose is straight chain, glycogen has side branches. Is it 1 mark?
Compacts molecules. More glucose in less space in the cell.
No osmotic effect. They do not diffuse out of cells

4) Pedigree diagram to show that moyamoya is caused by dominant allele, probability of child from persons 3 and 4
50%. Need to show parental phenotypes, genotypes, gamete genotypes, possible offspring genotypes and phenotypes

5) phospholipid bilayer transport multiple choice,

6) cholesterol study in different countries, give dietary advice from table

7) Cholesterol levels, blood clot fill the gap, how could this lead to a heat attack
Blood clot blocks coronary artery. Reduced blood flow to the heart. Less oxygen and glucose reach heart muscle cells. Less aerobic respiration. Less ATP produced. Heart muscle need a lot of ATP to contract

8) draw a line for the pulmonary artery, difference between capillary and vein, diffusion of CO2 and O2 comparison, explain how mammals transport gasses
Endothelium of capillary is one cell thick, vein has multiple layers of cell.
Rate of oxygen faster? Do they really mean rate? Credit correct manipulation of figures?
Many Alveoli provide large surface area. Ventilation of alveoli maintains concentration gradient. Blood moving maintains concentration gradient. Endothelium of capillary is one cell think, short distance, helps diffusion

9) different genotypes and how they affect life expectancy, how different amino acid affects haemoglobin structure

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
Aa has some protection against insect. aa have anaemia
Mutation is change to base sequence. Change in Amino acid sequence (primary structure), change in type and position of bonds between different R groups. For example, hydrogen, ionic, disulphide bonds. Change in protein 3D shape (folding). Haemoglobin binds less oxygen. Less oxygen carried to cells for aerobic respiration. Haemoglobing less soluble

(edited 7 years ago)

Reply 50

Original post by Darcy-Darling

I spoke about the osmotic effect. Water moves in causing them to swell/lyse x

would I be wrong, if I rambled on about how water is distilled and that it's pure; it doesn't contain any molecules or ions and that there will always be a high concentration of water outside the cell than inside the red blood cell so water keep on diffusing via osmosis down the concentration gradient. Causing cell to burst and likewise increase the volume of water in the red blood cell.

Reply 51

Original post by chemica

Sounds right!!

Reply 52

kosmooos

Original post by chemica

what did people put for "explain why the red blood cell burst or increased in volume, when placed in a distilled water?"

Water moves by osmosis from distilled water to red blood cells. Higher concentration of free water molecules outside red blood cells than inside. Higher concentration of solute inside red blood cells, so water is attracted inside red blood cells

Reply 53

Original post by Darcy-Darling

Sounds right!!

But in the exams i rambled more than I did there so -_- they'll probably take marks off

Reply 54

kosmooos

Original post by kdizzle97

I think I got 74.5%
Probably did it wrong though

I got something like that as well. Because it is a % decrease, we are comparing to initial number, so need to divide by larger number

Reply 55

Original post by kosmooos

I got something like that as well. Because it is a % decrease, we are comparing to initial number, so need to divide by larger number

Yep,it was 74.6% (something like 44.1-12.2/44.1 if I remember the numbers correctly )

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Reply 56

username1431415

Unofficial markscheme willing to help

Reply 57

Original post by splog23

Yep,it was 74.6% (something like 44.1-12.2/44.1 if I remember the numbers correctly )

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ohhh another question wrong :'( i did 44.1- the vitamin C of raw cabbage/ 44.1 x100) but I GOT 22.2 % somehow

Reply 58

Original post by chemica

But in the exams i rambled more than I did there so -_- they'll probably take marks off

Waffling doesn't matter though, as long as you managed to get those key points in

Reply 59