# AS Biology Edexcel IAL Unit 1 & 2 2015 watch

1. (Original post by Polpi)
Can someone please tell what the experiment was for the cooking time on potatoes please ? Like what did ya"ll write?
I struggled on this question, this is what I said:

1. use a variety of different potato species
2. create potato samples of equal sizes
3. repeat three times for each species of potato (3 samples for each)
4. wash the potato samples and leave to dry
5. Use a water bath to regulate a typical cooking temperature
6. also use normal room temperature as a control
7. put the sample in a closed beaker with a bung in it to prevent water entry and to collect the gas (by-products of catalase reaction)
8. place it upside down in the waterbath at cooking temperature
9. measure the volume of product given off in the gas collecting beaker
10. divide the volume of product by the time to get the initial rate of reaction
11. collect results, calculate mean etc

how many marks would I get for something like this? really just improvised on it haha
2. (Original post by AJC1997)
I struggled on this question, this is what I said: OMG I wrote a lot of similar points too like yours!! Em except I said vary the time for each test tube.i didn't have time to write the initial rate and measure volume of oxygen.Dammit.

1. use a variety of different potato species
2. create potato samples of equal sizes
3. repeat three times for each species of potato (3 samples for each)
4. wash the potato samples and leave to dry
5. Use a water bath to regulate a typical cooking temperature
6. also use normal room temperature as a control
7. put the sample in a closed beaker with a bung in it to prevent water entry and to collect the gas (by-products of catalase reaction)
8. place it upside down in the waterbath at cooking temperature
9. measure the volume of product given off in the gas collecting beaker
10. divide the volume of product by the time to get the initial rate of reaction
11. collect results, calculate mean etc

how many marks would I get for something like this? really just improvised on it haha
Hahah Omgg I wrote the exact same,except I mentioned idk why though very the time for each test tube and I didn't have time to finish that sentence off saying measure initial rate and measure volume of oxygen. You should get 4/5 marks at least
3. [QUOTE=Polpi;56100757]Hahah Omgg I wrote the exact same,except I mentioned idk why though vary the time for each test tube and I didn't have time to finish that sentence off saying measure initial rate and measure volume of oxygen. You should get 4/5 marks at least
4. So guys grade boundary high or low?
5. Hoping they'll be low </3
6. Is there still a chance to get a good grade if you kinda messed up unit 1 abd 3? /:
7. (Original post by Polpi)
Hahah Omgg I wrote the exact same,except I mentioned idk why though very the time for each test tube and I didn't have time to finish that sentence off saying measure initial rate and measure volume of oxygen. You should get 4/5 marks at least
me too! except I collected the gas in a syringe. And recorded the time taken to fill a certain volume to measure rate.
-Mentioned the potatoes cut to chips of the same length, height and width from the same part of the potatoes, ideally from the same parent plant :3
- the ones that were cooked were boiled at the same temp for 20 min. then all of them were blended for the same amount of time to get equal volumes of juice...
-The IV and DV, repeating..
-Oh and the control of raw potatoes.
8. When is arsey posting the model answers?

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9. (Original post by A84)
last 2... for reliability i wrote to repeat the expeirment, take averages, make sure human reaction time does occur etc
then next one improvements i said use other stuff like water and some other caffeintaed drinks and then plot the graph etc

what was 190 cm women/? there was no specific height we had to use!!
Increasing reliability by repeating investigation 3 times per student and by increasing sample size of investigation by including more students.

Woman of 190cm would have a higher peak rate than woman of 165cm and 170cm but lower peak rate than men of any height.
I wrote men have stronger skeletal muscles and stronger intercostal muscles (lol, idk)
10. (Original post by AvWOW)
me too! except I collected the gas in a syringe. And recorded the time taken to fill a certain volume to measure rate.
-Mentioned the potatoes cut to chips of the same length, height and width from the same part of the potatoes, ideally from the same parent plant :3
- the ones that were cooked were boiled at the same temp for 20 min. then all of them were blended for the same amount of time to get equal volumes of juice...
-The IV and DV, repeating..
-Oh and the control of raw potatoes.
what did u write for why galactose and glucose are monosaccharides
11. same I did write men have a broader chest cavity etc too
12. (Original post by AJC1997)
how to calculate mean I just said you find the difference in heart rate after drinking caffeine for each student and divide it by 3 to get the mean increase in heart rate.

reliability - three repeats for each student, make sure the caffeine content of each drink is measured accurately so the consumption is the same for each student.

improvement - control all other variables that affect heart rate, for example stress levels and activity levels - before and after drinking caffeine the students should be resting, they should also be in the same environment/surroundings when the test is undergone to isolate the key variable of caffeine

how to calculate probability - described saying a genetic inheritance diagram could be used and each parent was heterozygous so had Tt alleles meaning there was a 1/4 or 25% chance of their child being a sufferer after crossing their gametes, it said describe so they weren't looking for you to draw anything I don't think
For probability question I did the same as you but I realised the question was HOW and not "calculate probability" and so i added that the woman could undergo amniocentesis and the man could take cells from his saliva to see if there are any defective alleles. I hate how these questions were worded!
13. (Original post by AJC1997)
wasnt the 190cm question just asking 'what results would you expect for women with a height of 190cm?'

so just a similar trend to the 190cm for men - the peak rate would be greater than for 175cm/160cm women by a similar intervel to the increase from 160-175cm women?
and lower than the peak rate of men of any height.
14. (Original post by AJC1997)
I struggled on this question, this is what I said:

1. use a variety of different potato species
2. create potato samples of equal sizes
3. repeat three times for each species of potato (3 samples for each)
4. wash the potato samples and leave to dry
5. Use a water bath to regulate a typical cooking temperature
6. also use normal room temperature as a control
7. put the sample in a closed beaker with a bung in it to prevent water entry and to collect the gas (by-products of catalase reaction)
8. place it upside down in the waterbath at cooking temperature
9. measure the volume of product given off in the gas collecting beaker
10. divide the volume of product by the time to get the initial rate of reaction
11. collect results, calculate mean etc

how many marks would I get for something like this? really just improvised on it haha
Seems a good answer except that potato had to be from the same variety i.e same potato or from the same batch of potato (because the only independent variable was temperature) all other variables needed to be the same and ,from reading mark schemes, I got the feeling that examiners don't like the term "room temperature"
15. what did you guys write in that question about the difference between products of transcription and Replication?
16. (Original post by PinkRhinos)
For probability question I did the same as you but I realised the question was HOW and not "calculate probability" and so i added that the woman could undergo amniocentesis and the man could take cells from his saliva to see if there are any defective alleles. I hate how these questions were worded!
yeah, I was also thinking about maybe mentioning prenatal testing BUT the question already said that both parents were carriers - as they were heterozygous, meaning testing and amniocentesis would have no benefit as they already knew that they were at risk of giving birth to a sufferer.
17. (Original post by PinkRhinos)
and lower than the peak rate of men of any height.
Indeed, I estimated what the peak rate would be for 35 year old 190cm women - like 476dm-3 or something, which was an increase of similar interval to the 160-175 increase
18. (Original post by PinkRhinos)
Seems a good answer except that potato had to be from the same variety i.e same potato or from the same batch of potato (because the only independent variable was temperature) all other variables needed to be the same and ,from reading mark schemes, I got the feeling that examiners don't like the term "room temperature"
Well it's reassuring to here I didn't write complete rubbish for this question, I'm happy with 3+ marks for it haha
19. hey guys
hows prep going for bio unit 2?? how r u spending the revision time
20. (Original post by A84)
hey guys
hows prep going for bio unit 2?? how r u spending the revision time
I'm gonna start solving p.p tmw, u?

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