AQA BIOL1 Biology Unit 1 Exam - 16th May 2011

What is a definite C for Unit 1 btw?

Lets clarify this!

Lumen of Intestine (Ileum in the case of the question due to the epithelial cells) contains Villi.

On those villi are lots of Epithelial Cells.

Each Epithelial cell has lots of foldings called microvilli. This increases the surface area of the epithelial cells which allows for faster rate of diffussion to occur. (For this question I tried to use what I learnt from the other exam papers I done and wrote "So increases rate of diffussion after each explanation" hopefully those will earn me marks :P)

For the question it was the microvilli that was required to be explained as an adaptation. This is because microvilli are on the epithelial cells and Not villi on epithelial cells.

Anyway moving onto other questions, what did people get on the heart pressure questions? I got a 0.5 different (larger value (time) minus smaller value (time)). I got this as these were the times where the ventricle pressure was higher than the atria pressure. This causes the atrioventricular valves to be forced shut due to the pressure.

Also how many marks would this be for the phagocyte question? - Phagocytes surround (forgot to use engulf) the pathogen and wrap around it. This forms a vesicle inside the phagocyte (forgot to say phagosome), this then joins with another vesicle containing digestive enzymes which break down the pathogen and display the antigen on their surface to initiate T-cells and hence B-cells (immune response).


I hope I get good grades for this, I found the test alright but its just I ran out of time to get the last sentence in the very last question. I think I probs lost about 4-5marks at most, fingers crossed (I said the same thing las time I did it and lost lots of marks )

I didn't explain much more on the microvilli. I said about lots of mitochondria for aerobic respiration to form energy in the form of ATP for active transport to allow transfer of molecules to occur against concentration gradient. Also I said about the co-transport proteins for diffussion of molecules such as glucose/sodium which help diffussion to occur down conc. grad of sodium and against conc grad of glucose. Also I said about the close blood supply which reduces the diffussion distance and maintains conc. grad as glucose rich blood constantly moves away and low conc. glucose blood comes in. Also after each one I said it helps increase the rate of diffusion.

Something I forgot is enzymes on the surface of epithelial cells (e.g. Maltase) which help break down molecules into absorbable sizes.


Another thing, about the lactose question about diarrhoea (almost wrote about flatulence but read it again and realised). I said it moves in ileum and is not broken down and cannot be absorbed as it is too large. This lowers the water potential of lumen to lower than epithelial cells and this causes water to be diffused by osmosis down a conc. grad (from negative water potential to more negative water potential) causing water to be removed and diarrhoea to occur.

I forgot to write about mitochondria and all the stuff about sodium transport shizz :'(. i wrote about blood supply and maintains gradient. urghh i've effed it up.

Trust me you haven't. The last questions on the Unit 1 are generally 4-6 marks each and the mark scheme gives 7+ possible answers. This was a 6marker so I expect about 10 marking points. only like 3-4 points are really needed to be expalined and added with a "so rate of diffussion is increased".

Epithelial cell have villi on them the villi have a substructure called microvilli on them to further increase S.A. Sodium potassium pump and carrier protein help with changing the concentration so that glucose can be absorbed.

Did you put short diffusion pathway as the epithelial cell is one cell thick?

I dont understand. If the epithelial cell is a cell, how can it be one cell thick? surely u mean that the lining is one cell thick?

guys for the lactose i put it moves in intestine and lowers water poten so water flows from cells to intestine lol

that's right.

oh right thanks, i thought it goes to cell first or sumfin like that lol
and the last Q, trust me dont worry bout it, u will get at least half

isit me or i still think overall i did well but i begin to realise few mistakes after the exams, happens every time lol

Thanks!
I think i got half on that, then like all the calculations wrong, + 5 from all the paper + perhaps losing 1 for not saying that the vaccination will attack the nerve cells :| (did you put that !!!!!!!! ?)

Sigh, cant believe I'm still here. Must.....continue.......unit2 revision........

Time to unsubscribe :¬D

/Cya

Ps. Effkay: Go Sleep man

i basically lost marks on calculations and small minor marks here and there, overall it hink i got around 42 or so lol

was hoping for 50 but didnt expect those calculations, jus culdnt do it

I'm hoping it will be less than 45 for an A as june 2010 didnt have any calculations and questions were rather clear cut.

few tricky Q on that paper we did much more than june 2010.

im quite sure A will be around 40 marks

For the first 'conclusion' i wrote correlation not causation, other factors, only 24countries, cant generalise it, positive correlation though. 3?

Then for second one i wrote just about memory cells and how it can fight it off, so i think 2? \: