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AQA AS Biology Unit 2 Revision

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What's the difference between the notes you posted in December labelled unititled 2.doc and the revision notes PDF you posted recently?

Reply 21

Hanna07

Original post by Ptm09

Hello, apologies if this proves to be inconvenient but is it possible please to note the equations for common mathematical questions (such as percentage increase/decrease, calculating the duration of anaphase etc.) which appear in the biology exams? I am OK with the content but the calculations are my weakness!
Thank you very much!

Yes please do I struggle with that part too!

Reply 22

oak12

Original post by Ptm09

1:

Bases - Adenine = Thymine, Cytosine = Guanine

e.g. 24% Adenine, therefore 24% Thymine = 48%, therefore the other 52% is Cytosine/Guanine (52% / 2 = 26% each)

2:

If given number of bases, to determine number of AAs coded for - divide by 3
If given number of AAs, to determine how many bases code for it - multiply by 3

e.g. number of bases = 300, therefore number of AAs = 100
number of AAs = 50, therefore number of bases = 150

3:

Mitosis keeps chromosome number the same and halves dna mass
Meiosis halves chromosome number and quarters dna mass
e.g. chromosome number is 20, dna mass is 200 mitosis - chromosome number is 20, dna mass is 100 meiosis - chromosome number is 10, dna mass is 50

4:

Measuring Rate = Volume / Time

5:

If given diploid number of chromosomes, to determine number of possible combinations of chromosomes in gamete -

2 to the power of number of pairs

e.g. 4 chromosomes, so 2 pairs, so 2 to the power of 2 = 4 combinations
8 chromosomes, so 4 pairs, so 2 to the power of 4 = 16 combinations

6:

If given time for cell cycle - use percentage of cell in each stage to calculate length of time in each stage

e.g. cell cycle last 20 hours, 20% of cells in anaphase, therefore length of time in anaphase is 20% of 20 hours = 4 hours

7:

percentage change = (difference/original) x 100

e.g. percentage change from 36 to 54, difference = 18 & original = 36, so (18/36)x 100 = 50%

Reply 23

Ptm09

Thank you so so much!

Reply 24

oak12

Original post by Tplox

what exactly is the difference between cohesion and tension?

cohesion = how water particles stick together

tension = the pull on the column of water

Reply 25

oak12

Original post by jadys10

What's the difference between the notes you posted in December labelled unititled 2.doc and the revision notes PDF you posted recently?

these revision notes are the most up to date

Reply 26

Tplox

Original post by oak12

these revision notes are the most up to date

http://filestore.aqa.org.uk/subjects/AQA-BIOL2-QP-JUN13.PDF

1 (b) (ii)
could you possible attach a diagram for that answer
the ms doesnt give a diagram..
thanks

Reply 27

oak12

Original post by Tplox

http://filestore.aqa.org.uk/subjects/AQA-BIOL2-QP-JUN13.PDF

1 (b) (ii)
could you possible attach a diagram for that answer
the ms doesnt give a diagram..
thanks

1bii

1bii.jpg9.6KB

Reply 28

junior Angela

what are the characteristics of the insect