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AQA BIOL4 ~ 11th June 2013 ~ A2 Biology

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Reply 720
Avatar for Tikara
Tikara
Original post by hollywils
Can anyone please tell me the advantages and disadvantages of using inorganic artificial fertiliser?!


Posted from TSR Mobile


Advantages
-Easy to handle
-Known chemical content
-Easy to control mass added
-Is soluble so releases nutrients quickly

Disadvantages:
-can be expensive
-May lead to eutrophication (bad for environment)
-May not contain some nutrients

I can't really think of any others right now but surely there are more disadvantages that I can't think of :frown:
Oh, ok, thanks.
Now I know NADP is in plants. I thought it was universal. :tongue:
Reply 722
Avatar for emah123
emah123
5
is everyone feeling confident for this exam?? lol im not :frown: i hate those HSW qs!!
Original post by Scienceisgood
Question guys;

After going through June 2012 paper, it says no NADPH produced during electron transport chain, I thought NAD was reduced, not NADP?

Question.PNG

EDIT:
Said Jan 13 by mistake.

NAD and FAD are used in respiration.. NADP is in photosynthesis. there's an electron transport chain in photosynthesis
Reply 724
Avatar for kitkat95
kitkat95
3
Original post by hollywils
Can anyone please tell me the advantages and disadvantages of using inorganic artificial fertiliser?!


Posted from TSR Mobile

Advantages:
-Releases nutrients quickly in to the soil
-They are concentrated so a smaller amount is needed than what would be needed with a natural fertiliser
-Clean chemicals used/ not smelly

Disadvantages:
-Expensive
-Readily leached
-May spread to other areas
Are the Last 3 questions still 5 marks each, i think i heard it has changed. Does anyone have the January 2013 paper, ive done every paper except for that one. Can someone please send me a link or email it to me, i would be so glad.
Thank you. :h:
Original post by jennyruneckles
HELP!!! I have been doing the june 11 past paper and don't understand why the answer would be 4?


6 Sea otters were close to extinction at the start of the 20th century. Following a ban
on hunting sea otters, the sizes of their populations began to increase. Scientists
studied the frequencies of two alleles of a gene in one population of sea otters.
The dominant allele, T, codes for an enzyme. The other allele, t, is recessive and
does not produce a functional enzyme.
In a population of sea otters, the allele frequency for the recessive allele, t, was found
to be 0.2.
6 (a) (i) Use the Hardy-Weinberg equation to calculate the percentage of homozygous
recessive sea otters in this population. Show your working.


t + T = 1
t = 0.2
T = 0.8

T2 + t2 + 2tT = 1
0.82 + 0.22 + 2tT = 1

EDIT:
So, since t = 0.2
0.22 = 0.04
multiply by 100 = 4
(edited 10 years ago)
Original post by sikhtank27
whats HSW?


How science works.
Don't worry i found them, whoever needs it just check the first page to this thread
Reply 729
Avatar for Tikara
Tikara
Original post by jennyruneckles
HELP!!! I have been doing the june 11 past paper and don't understand why the answer would be 4?


6 Sea otters were close to extinction at the start of the 20th century. Following a ban
on hunting sea otters, the sizes of their populations began to increase. Scientists
studied the frequencies of two alleles of a gene in one population of sea otters.
The dominant allele, T, codes for an enzyme. The other allele, t, is recessive and
does not produce a functional enzyme.
In a population of sea otters, the allele frequency for the recessive allele, t, was found
to be 0.2.
6 (a) (i) Use the Hardy-Weinberg equation to calculate the percentage of homozygous
recessive sea otters in this population. Show your working.


This ones simpler then it looks :P

using the hardy weinberg equation

p2 + 2pq + q2 = 1

q2 is the frequency of the homozygous recessive

p = frequency of dominant allele
q = frequency of recessive allele

So then as you are given the freq. of recessive alleles (q)
to find the frequency of homozygous recessive you just square it

so q2 = (0.2)2 = 0.04
which as a percentage (x100) is 4%

hope that helps!
(edited 10 years ago)
Reply 730
Avatar for Tikara
Tikara
Original post by emah123
is everyone feeling confident for this exam?? lol im not :frown: i hate those HSW qs!!


I suggest you do all the application questions in the nelson thornes book - it helps gets you into the mindset of hsw :P
Reply 731
Avatar for jjgaffney
jjgaffney
so annoyed about this exam i know the content but the questions are hard. Any last minute tips?
Reply 732
Avatar for Son234
Son234
I'm actually enjoying these how science work questions

The key thing is to not over complicate it as the answers are fairly simple

And also all the information you need is given in the question to answer it

So read the question extra carefully especially Q7

but I'm sure everyone does that anyway :smile:




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Original post by Tikara
This ones simpler then it looks :P

using the hardy weinberg equation

p2 + 2pq + q2 = 1

q2 is the frequency of the homozygous recessive

p = frequency of dominant allele
q = frequency of recessive allele

So then as you are given the freq. of recessive alleles (q)
to find the frequency of homozygous recessive you just square it

so q2 = (0.2)2 = 0.04
which as a percentage (x100) is 4%

hope that helps!


Thanks so much!! :smile:
I realised that I did the square root instead of squaring it :tongue:
Original post by jjgaffney
so annoyed about this exam i know the content but the questions are hard. Any last minute tips?


That's AQA for you.

They cross the line, reverse over it, cross again and then step on it!
I swear, I know the content but some of these questions make me look as though I know NOTHING!
Oh yeah and guys, if something comes up tomorrow about global warming, don't forget to say the obvious "CO2 is a Greenhouse Gas which contributes to global warming". That gets you TWO MARKS! Just for stating the bleeding obvious!
Reply 736
Avatar for MrProff
MrProff
Did a day of revision today, no idea why I'm doing this exam, got a high C first time round. The chemistry unit the day after that I failed is the one I've got to knock on the head, good luck all!
nitrogen fixing bacteria are not saprobiotic organisms are they?
Original post by master y
nitrogen fixing bacteria are not saprobiotic organisms are they?


This may sound nit picky and they are not saprobiontic organisms.
I was told I will get penalised for saying saprobiotic.
Original post by master y
nitrogen fixing bacteria are not saprobiotic organisms are they?


Negative.

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