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AS biology

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ruby92:

--- Quote from: ruby92 on April 10, 2010, 07:52:22 pm ---m/j 2004
7
4
5
23-hw is it b wont it be D
30

--- End quote ---
this is frm paper 1

also o/n 2004 paper 1
38
27
22
13

MaNi_DaDuDe:
Thanks for helping.

+rep. :)


--- Quote from: tmisterr on April 10, 2010, 08:46:52 am ---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)



--- End quote ---

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  ;D ;D

ruby92:
m/j 2008  paper 1
16,21,28

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