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BIOL4 Biology Unit 4 Exam - 13th June 2011

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finished looking over all the content, now I guess its just practising the questions! it's a shame there's not more past papers.. :/
Reply 101
Could you send me the revision notes too please? I'm really panicking about both exams :frown: I got an E in biol4 and I need a B for university I spent that long on the two last questions I didn't have time to finish the rest of the exam!

The irony of it is I got full marks on the last two questions! :L

Anyone got any revision tips for biol4 or biol5? It's mainly actually asking the questions I'm having problems with...
Reply 102
Original post by angel1992
basically am stuck on genetics part. If a gene codes for a specific polypeptide chain how can you have different alleles which are the same gene because different alelles have different polypeptide chains( they usually have one amino acid thats different) and that would therefore make them different genes

Is it that the differences are so small, i.e. one amino acid difference still makes it the same polypeptide chain?

very confused
any ideas or explanation would be helpful?


i'm not sure i understand the question fully. however, the idea of an allele is to code for different polypeptides to do the same thing. So, if the gene codes for eye colour then one allele of that gene will code for the protein to produce a green eye colour while another allele that also codes for eye colour will be for blue eyes. They are both expressed by a gene but because the phenotypes generated are different they are different alleles. Makes sense?:smile:
Original post by INeedToRevise
Guys, in glycolysis when triose phosphate is oxidised, does each triose phosphate molecule lose 2 hydrogens?



SHort answer is NO.

Well, if you think about it there are 2 molecules of TP turned into 2 molecules of pyruvate

2 molecules..1 hydrogen each
Reply 104
Original post by Boo!xx


Ty for the papers.. but I dont know if this is happening to anyone else, but when I click on the link for the bio4 revision notes it comes up with the bio5 revision notes? :confused:

Google, heck grammar notes , click the 1st web site for some reason i cant paste the link.
hate mac pro!
Reply 105
Original post by al_habib
Google, heck grammar notes , click the 1st web site for some reason i cant paste the link.
hate mac pro!


Ah ty :] I'm on a mac too! :biggrin:
Reply 106
there you go..UNIT 4 & 5 BIO NOTES http://www.heckgrammar.co.uk/index.php?p=10312
q9b jan8 BYA5
Here

Thats the part where I m weakest ! Basically population (quadrats-..)

1.Dunno why we cant use transects here!
2.Then last point in the MS where they say : Take ave. then multiply by area of field
Original post by arvin_infinity
q9b jan8 BYA5
Here

Thats the part where I m weakest ! Basically population (quadrats-..)

1.Dunno why we cant use transects here!
2.Then last point in the MS where they say : Take ave. then multiply by area of field


Thanks for your answer above :smile:

A transect is usually used to measure a series of changes over a distance, e.g. succession. The question is asking for estimating the daises in field. So you use quadrats. This is my standard answer that usually gets all the marks:
1. Lay down two measure tapes at right angles.
2. Obtain coodinates using a random number generator or throwing dice.
3. Place the quadrat at the intersection of the coordinates.
4. Count the number of ......

The last point is referring to taking an estimation of all the number of daises on the whole of the field. So I guess you would take an average of your sample and multiply it by the area of the field.
(edited 12 years ago)
Original post by INeedToRevise
Thanks for your answer above :smile:

A transect is usually used to measure a series of changes over a distance, e.g. succession. The question is asking for estimating the daises in field. So you use quadrats. This is my standard answer that usually gets all the marks:
1. Lay down two measure tapes at right angles.
2. Obtain coodinates using a random number generator or throwing dice.
3. Place the quadrat at the intersection of the coordinates.
4. Count the number of ......

The last point is referring to taking an estimation of all the number of daises on the whole of the field. So I guess you would take an average of your sample and multiply it by the area of the field.


Your answer is quite thorough +rep
So the number we get after taking average is for parts of the area we are investigating and when we multiply it out we get estimation of the whole area

I remember my teacher said we cant throw things..
Think about it dice is not really random cause ! say u get 1--6 ONLY
(edited 12 years ago)
Reply 110
Original post by arvin_infinity
Your answer is quite thorough
So the number we get after taking average is for parts of the area we are investigating and when we multiply it out we get estimation of the whole area
+rep


yepppp.....

mark field out. obtain random coordinates using a dice or random number generator within your limits. plop the quadrat there. do as many time within time given for experiment to improve reliability. take average. times by total area of field. bobs your uncle, do a little jig and you have your estimate.


ps. you have to do the little jig or the estimate is totallllllllly wrong..... :smile:
Original post by SK-mar
yepppp.....

mark field out. obtain random coordinates using a dice or random number generator within your limits. plop the quadrat there. do as many time within time given for experiment to improve reliability. take average. times by total area of field. bobs your uncle, do a little jig and you have your estimate.


ps. you have to do the little jig or the estimate is totallllllllly wrong..... :smile:


U do the lil jig somewhere in between just to make it more random ..:smile:
Now I need to learn % cover!
Here is what I found in TSR but didnt understand it

So they better way to estimate the population is by ground cover % which is done by a square frame which has pointers say for example: if it has 10 pointers and we use it 10 times on the same quadrant we end up with 100 readings, since many plants touch the same pointer we end up with readings averaging 300-400%

10 x 10 = 100 readings.. but if you take out the average of how many plants are touching the pointer, we end up with 300-400% cover
three plants per pointer i.e 300/100 times 100 to get % cover which is 300% =]
Original post by arvin_infinity
Your answer is quite thorough +rep
So the number we get after taking average is for parts of the area we are investigating and when we multiply it out we get estimation of the whole area

I remember my teacher said we cant throw things..
Think about it dice is not really random cause ! say u get 1--6 ONLY


Thanks for rep. And yep thats right.
Thats weird. Examiners seem to accept that answer. Its all over the markschemes
Reply 113
Original post by arvin_infinity
U do the lil jig somewhere in between just to make it more random ..:smile:
Now I need to learn % cover!
Here is what I found in TSR but didnt understand it

So they better way to estimate the population is by ground cover % which is done by a square frame which has pointers say for example: if it has 10 pointers and we use it 10 times on the same quadrant we end up with 100 readings, since many plants touch the same pointer we end up with readings averaging 300-400%

10 x 10 = 100 readings.. but if you take out the average of how many plants are touching the pointer, we end up with 300-400% cover
three plants per pointer i.e 300/100 times 100 to get % cover which is 300% =]



for percentage cover you use quadrats again, but you grid the quadrats using string or something like that. you then randomise it by using coordinates again. however, this time you count how many plants (that your investigating) are in the whole quadrat. so if the plant your investigating covers 5/10 squares within the quadrat then thats 50% obviously. if one square is covered only half then you still count it. then you work out the average as before....
Reply 114
Urghh i really hate respiration :frown: Ive finally managed to get the theory remembered but then coming to apply it to the questions is soooo hard. </3
Reply 115
Original post by arvin_infinity
q9b jan8 BYA5
Here

Thats the part where I m weakest ! Basically population (quadrats-..)

1.Dunno why we cant use transects here!
2.Then last point in the MS where they say : Take ave. then multiply by area of field


hi, can i just ask where your getting these past papers from. on the aqa website there are only like 2 . thers no 2008 ones. please can you tel me how to find more past papers
Reply 116
Original post by Boo!xx


Ty for the papers.. but I dont know if this is happening to anyone else, but when I click on the link for the bio4 revision notes it comes up with the bio5 revision notes? :confused:

hiya, your right about the link, try ths new one:

http://www.studentcreche.co.uk/resources/biol4.pdf
ahhhhhh! I hate this exam!

i'm resitting this. such a pisstake! its the HSW and the way they word it!
Original post by User12399
ahhhhhh! I hate this exam!

i'm resitting this. such a pisstake! its the HSW and the way they word it!


Yep. I'm so pissed off that all this completely irrelevant Ecology crap is what will get me into university to study Pharmacology. It is so annoying. I wish we got to choose modules or something for the A Level.
I just did the Jan 10 exam earlier as a mock and I got 84% (bearing in mind I got 55 UMS in January.. a D) so I think the revision is beginning to pay off. I think, though, that that exam was slightly easier than the Jan 11 one?

I'm just frustrated there's not more practice papers!

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