AS biology

[ruby92]

M/J 2003
paper 1

19
4
18
29
25

[tmisterr]

19. answer is C. in semi-conservative replication, the new DNA helix has one old strand and one new strand so the number with nitrogen 15 keeps on reducing by half.

18. answer is A. each tRNA molecule is specific to one amino acid so all you need is 4 tRNA since the polypeptide chain consists of only these four, repeating themselves, so the tRNA molecules can be re-used

4. if they have the same water potential, osmosis will be at equilibrium so water moving into cells will equal water moving out so in the end, there will be no change in length so initial length/final length will equal to 1. read of graph, answer is 0.45 i.e C

29. C, vital capacity is the maximum amount of air breathed in, and then breathed out.

25. C again, the more negative the water potential the lower the water potential, and as u know water movers from high to low water potential so it moves from high water potential in cell 3 (-4kPa) to a lower water potential in the environment (-5kPa) and from the environment into cell 1 which is at an even lower water potential (-7kPa)

[ruby92]

@timsterr
thnkx a loooottttttt 

[tmisterr]

no problem!

[ruby92]

m/j 2004
7
4
5
23-hw is it b wont it be D
30

[ruby92]

m/j 2004
7
4
5
23-hw is it b wont it be D
30

this is frm paper 1

also o/n 2004 paper 1
38
27
22
13

[MaNi_DaDuDe]

Thanks for helping.

+rep.

19. answer is C. in semi-conservative replication, the new DNA helix has one old strand and one new strand so the number with nitrogen 15 keeps on reducing by half.

18. answer is A. each tRNA molecule is specific to one amino acid so all you need is 4 tRNA since the polypeptide chain consists of only these four, repeating themselves, so the tRNA molecules can be re-used

4. if they have the same water potential, osmosis will be at equilibrium so water moving into cells will equal water moving out so in the end, there will be no change in length so initial length/final length will equal to 1. read of graph, answer is 0.45 i.e C

29. C, vital capacity is the maximum amount of air breathed in, and then breathed out.

25. C again, the more negative the water potential the lower the water potential, and as u know water movers from high to low water potential so it moves from high water potential in cell 3 (-4kPa) to a lower water potential in the environment (-5kPa) and from the environment into cell 1 which is at an even lower water potential (-7kPa)

[tmisterr]

M/J 04
 4. hydrolytic enzymes are found in the lysosomes and are used for things like phagocytosis to activity in the lysosomes should be greatest. C
 5. amino acids are the building blocks of proteins, and proteins are synthesised in ribosomes which are found on the surface of Rough Endoplasmic reticulum so on the RER is where radioactivity will be highly concentrated so C
7. C again lol, well a dipeptide consists of 2 amino acids, so 12 amino acids can combine in 12² different ways so 144.
23. Well no not D, it is definitely B. first transcription takes place and mRNA is formed, it will have the sequence of C, and then from the mRNA, tRNA is then tranlated, and it will have the sequence of B. Just remember, A pairs with T, but in RNA T is replaced with U and C always pairs with G.
30. C again!!! the further to left the graph is, the more affinity it has for O₂ so it will release oxygen at only low partial pressures of oxygen. as you can see from the graph, the smaller the mammal, the further to the right the graph is, so the haemoglobin of the smaller mammals have a lower affinity for oxygen and can release it at lower partial pressure. Read on the Bohr effect and the properties of myoglobin and fetal haemoglobin compared to adult haemoglobin, it will help you understand.

O/N 2004
13. A, it requires a bit of math knowledge, but thats the generally formula. for example if you have 10 amino acids which combine to from proteins of 3 amino acids per protein then the total number of different proteins is 10³ which is 1000 different proteins...
22. B. CAT will first be transcribed to mRNA GUA and then translated to tRNA CAU
27. as you know, red blood cells do not have a nucleus, endoplasmic reticulum or mitochondria so AEROBIC respiration, protein or lipid synthesis cannot take place, no protein synthesis means no hydrolytic enzymes can be produced so phagocytosis  cannot take place. Active transport can however take place if ATP is produced ANAEROBICALLY!
38. D. energy used for growth, other life processes and lost in respiration originate from the glucose produced  by photosynthesis which is respired. so add all these three, you get D.

[ruby92]

thnkx 

[ruby92]

m/j 2008  paper 1
16,21,28

[sameee]

m/j 2008  paper 1
16,21,28

Helllo ruby92,
Q16.the concentration of sucrose solution, in mol dm–3, that has the same water potential as the cell sap
before immersion, will be the one that wont cause a change in lenght, that is, thereisnt any NET loss of water, nor gain, consequently, the final lenght and initial lenght will be equal, now, when you find their ratio, it would be equal to one, from the graph draw a horizontal line that would just touch the curve, then draw a verticel and take aa reading, it should be 0.45, which is C.

Q21.The RNA triplet UAG acts as a stop codon terminating the synthesis of a polypeptide, therefore you need a DNA triplet which must be an ATC, this should be present in the squence being given, now, if you move along the DNA squence given you can spot that at the 2nd arrow,between the A and the C, a T can be introduced, thus forming the DNA triplet ATC, which i had just mentioned, as soon the ribosome reaches this triplet, mRNA translation will cease. Therefore the answer is B.

Q28. well, one cardiac cycel = one heart beat, this includes the three phases.....As, VS and diastole. according to the bar given, there are 2 repetitive cycles of the three phases i had just mentioned, and the duration is 1.5s.
Now, to find the number of beats per minute, simply use ratios: 2 beats in......1.5s
                                        therefore,                                X beats per.......................60 s
cross multiply,
therefore X=2*60/1.5 = 80.

Hope that you understood them and that i helped.

[ruby92]

yes u did 
thnkx a lot sameee

[sameee]

yes u did 
thnkx a lot sameee

Your welcome.