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Biology Edexcel Unit 4 13/06/08

I put:

- Pinch skin and clip on the calipers
- Read measurements
- Done at 4 different sites (only listed two; back of arm and sides of waist)
- Find average skinfold thickness by taking the mean.
- Look up values of skinfold thickness in a table depending on age to get % body fat

Its in your text :biggrin:

Reply 41

yassir

1

i guess 4 was not too bad but 5 was hard man. come on studentbug get us the synoptic paper b4 wednesday!!!!!

Reply 42

xZainabx

robinsons

Umm for microbio what did everyone put for the first q:
Nucleus: (eukaryote)
Capsid: virus
Flagellum: (prokaryote)
Petidoglycan wall: bacteria

I'm pretty sure I got the bracketed ones wrong..

I put
Nucleas- yeast
Capsid- virus
Flagellum- bacteria
Pep wall- mould

Yes I do realise yeast and mould would be under fungi but Im hoping they know what I mean :s-smilie:

Reply 43

yassir

1

how ( if anyone ) did you find food science?

Reply 44

Covenant Chris

OP

yassir

i guess 4 was not too bad but 5 was hard man. come on studentbug get us the synoptic paper b4 wednesday!!!!!

Keep dreaming. :p:

Reply 45

studentbug

yassir

i guess 4 was not too bad but 5 was hard man. come on studentbug get us the synoptic paper b4 wednesday!!!!!

You can't lol, they dont release it until after the exam, and anyway that would be cheating and ILLEGAL. So even if i found a way, i would never do it.

I didn't do so well on the relative sweetness thingy, in the test i made up some method where i said crush the fruit, dissolve with water, filter off sugar solution, add benedicts reagent, use colourimeter to determine concentration, convert to relative scale

EDIT: Just looked in the text book, that was half right xD yay!

Reply 46

yassir

1

studentbug

You can't lol, they dont release it until after the exam, and anyway that would be cheating and ILLEGAL. So even if i found a way, i would never do it.

lol uv taken away my ever-so tiny bit of hope that i had of getting that paper.
i realise this needs mentioning b 4 i get filed a lawsuit :eek:

i was only joking.... (partly anyway)

studentbug

I didn't do so well on the relative sweetness thingy, in the test i made up some method where i said crush the fruit, dissolve with water, filter off sugar solution, add benedicts reagent, use colourimeter to determine concentration, convert to relative scale

ah i jus wrote crush the fruit, then separate into different concentrations ( the word i was looking for here was colourimeter but i kept thinking of calorimeter which was not right). then finally i said taste to find lowest conc. at which sugar can be tasted. and i stuck in sucrose has a RS of 1.0 jus for the heck of it.

Reply 47

JayG99

ps7

#i sed make a soloution of apply juice from apples before riepnign and durign riepening
use the same conc for each type of apple juice for each test
record the min conc at which it can be tasted
then i made a reference to a blind test
and the person shud rinse thier mouth in between tastings

That's a fantastic answer...wish I'd done that.

I went for cutting the apples and tasting them to determine relative sweetness...which is a bit of a *******s way but to be frank, the way the mark scheme want it can have many limitations too.
**** questions, tbh.

Reply 48

rose90

shungun

yes...i had the same problem....i didnt know how to measure the diastole and systole...wrote some junk....EXACTLY what i was thinking abt the skinfolding thing...i looked at the book after the exam and i was like OMG this want supposed to be learnt by us...what did you write for the skinfold thing? i just wrote that you find the thickness because the skinfold is mainly adipose tissue and hence it contains a lot of subcutainous fat then measure the length...then multiply to get the volume...(lol)
then i said that use the avg density to estimate mass...
(sorry i know i wrote some rubbish but could someone tell me the marks i will get if any?) it was 4 marks OMG :eek:

u guys will laugh i made it up i was like ok pull the skin and measure with a caliper (i wrote caliper coz i remeberd measuring the snails in wales with it LOL) crazy then all i said was measure and convert to body fat % :frown:

wrong wrong wrong

Reply 49

nakedinthecityagain

for the micro part in unit 4:

7)b)
- was i right in putting only azotobacter would grow in the growth medium??
-my reasoning was that it is the only type of bacteria which required it's nitrogen source in the form of gas and that it needed aerobic conditions, both of which were provided in the experiment.

8)b)i)
- how would you count the number of viable cells in the liquid culture??
i didn't have a clue... :frown:

and how on earth did you calculate the number of generations in the question right at the end??
i didn't know what to use for the N0 and N1 values!

Reply 50

Peel

10

kizmo

for the micro part in unit 4:

7)b)
- was i right in putting only azotobacter would grow in the growth medium??
-my reasoning was that it is the only type of bacteria which required it's nitrogen source in the form of gas and that it needed aerobic conditions, both of which were provided in the experiment.

8)b)i)
- how would you count the number of viable cells in the liquid culture??
i didn't have a clue... :frown:

and how on earth did you calculate the number of generations in the question right at the end??
i didn't know what to use for the N0 and N1 values!

I think 7B is correct.

8bi. To my knowledge you use dilution plating. Basic idea: make a series of known dilutions of the a given liquid culture, spread the diluted culture on an agar's plate (ensuring aseptic technique is used), leave them to grow, count the colonies and work that out as a fraction of the original amount.

You had to use the log10 values from the graph, and the formula.

(The N0 and N1 values are used in the lincon index which estimates the population size not the number of generations!)

Reply 51

x_reggg

kizmo

for the micro part in unit 4:

7)b)
- was i right in putting only azotobacter would grow in the growth medium??
-my reasoning was that it is the only type of bacteria which required it's nitrogen source in the form of gas and that it needed aerobic conditions, both of which were provided in the experiment.

8)b)i)
- how would you count the number of viable cells in the liquid culture??
i didn't have a clue... :frown:

and how on earth did you calculate the number of generations in the question right at the end??
i didn't know what to use for the N0 and N1 values!

7b. i wrote azobacter too :biggrin:

i wrote it was the only one that needed the exact conditions in the apparatus and also went to saying why all the other ones couldn't survive just in case.

8bi. i compltely halted here XD i wrote how do to a typical cell count of bacteria in liquid culture, but then i figured out half way it wouldn't tell if they were alive or not :frown:

i remembered the correct method (pour plate dilution method) afterwards, but i didn't have the time to change my answer or the memory to know what happened in it exactly :frown:

all i remembered was that you needed to dilute it :mad:

the number of generations: omgggggggggggggggg i just re-read the question and found out i completely did it wrong :frown:

there's no need to know the values of N0 and N1. the graph and the values on it are already in log, so all you needed to do was (8.2-7) /log2 :mad:

i completely forgot it was already logged and logged 8 and 7 :frown:

Reply 52

annarchy

10

kizmo

for the micro part in unit 4:

7)b)
- was i right in putting only azotobacter would grow in the growth medium??
-my reasoning was that it is the only type of bacteria which required it's nitrogen source in the form of gas and that it needed aerobic conditions, both of which were provided in the experiment.

8)b)i)
- how would you count the number of viable cells in the liquid culture??
i didn't have a clue... :frown:

and how on earth did you calculate the number of generations in the question right at the end??
i didn't know what to use for the N0 and N1 values!

I didnt put azo, because it was underwater.... arrrghhhh.

i had never heard of dilution plating but that was the correct answer.

the other question i got wrong was penicillin - didnt study that at all... i didnt know waht indicator medium was - ARGH such easy marks i threw away with just revising parts of the syllabus i thought are more likely to come up...

im happy yoghurt came up though, that saved me... and countless graphs.

As for the core, i didnt revise plant light detection, wrote the wrong thing for the balls question, and lost 2 marks for the Krebs question...

So by my estimation, I have got at least 38 out of 70, which is crap but not surprising... I think my biology overall will be a C borderline B maybe, if there are miracles...

Reply 53

jado91

this paper was a piece of cake compared to the past exams! i mean the essay question with the neurones and there functions was the easiest thing we could get i filled up the whole two pages. as for the first question with the hormones the one for uterine contractions is oxytocin, adrenaline has a bunch of effects i wrote increases heart rate, the LH is released from the pituitary gland. the option c was a bit annoying but also pretty easy i remember the question to test changes in systolic and diastolic pressures i just said u get a bunch of ppl same age same sex bla bla and give em doses of adrenaline then measure their heart rates. but the worst part of the exam was the stupid subcutaneous fat crap i mean they expect us to actually memorize crap like that!

Reply 54

mistereyeciti

the poll is a normal distribution!

Reply 55

Peel

10

x_reggg

the number of generations: omgggggggggggggggg i just re-read the question and found out i completely did it wrong :frown:

there's no need to know the values of N0 and N1. the graph and the values on it are already in log, so all you needed to do was (8.2-7) /log2 :mad:

i completely forgot it was already logged and logged 8 and 7 :frown:

I did the exact same thing :frown:

.

Reply 56

jado91

rose90

u no the structure in 4c was that the alveoli right?

and role of aortic/san reflex was parasympathetic one?

and then how on earthhh do u measure distole and systole?

and lol sorry but the skin folding experiement if you look in the unit 4 book its in the food tech option B!!!!! not C?!?!

-the structure was alveoli yes i just started writing the three features cuz i ddnt really know any adaptations of other parts of the lungs
-yea you have to explain the parasympathetic inhibition of the san and increase in the delay at the avn to decrease heartrate and decrease pressure in aortic arch
-you measure the diastole and systole by giving a bunch of standardized candidates doses of adrenaline or subjecting them to exercise then measuring their pressure i ddnt specify how but theres that pump thingy i dnt knw its name, then you just increase the dose to increase their heart rate and measure their pressures after each one.
-i dont know about the supid skinfold measurement it really pissed me off cuz i just made up a method of my own to measure it but my friends who took option c like me knew how to answer it and said theres this device u have to use so i guess its in option c :s-smilie:

a question to you now. wat was the pressure you got for the differences in occurence of men with heart disease between high fat and normal fat? how dd u get it? personally i calculated the percentage at high fat which was 38/200x100 19% and subtracted from it the percentage at normal fat which was 10/200x100 which was 5% answer 14% please say you did the same

Reply 57

JayG99

mistereyeciti

the poll is a normal distribution!

LOL!

We're so cheesy... :wink:

Reply 58

roberto775544

i so failed unit 4 again

what do we think they were looking for for the essay bit?

Reply 59

rose90

jado91

-the structure was alveoli yes i just started writing the three features cuz i ddnt really know any adaptations of other parts of the lungs
-yea you have to explain the parasympathetic inhibition of the san and increase in the delay at the avn to decrease heartrate and decrease pressure in aortic arch
-you measure the diastole and systole by giving a bunch of standardized candidates doses of adrenaline or subjecting them to exercise then measuring their pressure i ddnt specify how but theres that pump thingy i dnt knw its name, then you just increase the dose to increase their heart rate and measure their pressures after each one.
-i dont know about the supid skinfold measurement it really pissed me off cuz i just made up a method of my own to measure it but my friends who took option c like me knew how to answer it and said theres this device u have to use so i guess its in option c :s-smilie:

a question to you now. wat was the pressure you got for the differences in occurence of men with heart disease between high fat and normal fat? how dd u get it? personally i calculated the percentage at high fat which was 38/200x100 19% and subtracted from it the percentage at normal fat which was 10/200x100 which was 5% answer 14% please say you did the same

its not check the book its at the end of option B! its crazy ugh i hated it

umm that was funny i completly forgot how to do it..and your probably right it was about percentage increase right? ive forgoton the questions =|

Biology Edexcel Unit 4 13/06/08

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