IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: Sticky on May 12, 2010, 10:13:08 pm
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Heyy Guys
Biology Paper 2 On Friday, How Are Your Preparations & Any Doubt or Predictions Please Post Them Here To Help Everyone Out :)
i have a question myself
nov 08, first variant, last question about water
thanks :D
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Some one help with my question please guys :(
thanks :)
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are aortic valves the same as semilunar valves
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No semi lunar valves are in the right side of the heart in the pulmonary artery, its the same as TRISCUPID valve
aortic valves are in the left side of the heart and it prevents blood flowing backwards from the left ventricle to the left atrium, its the same as BICUSPID valve
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Sorry Sorry semilunar valves are NOT the same as triscupid valve.
triscupid are the same as bicuspid but in the right side of the heart. i.e prevent back flow of blood from right ventricle to right atrium
but yes aortic valve and bicuspid valve are the same not semilunar valve
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but aorta doent have any valves... remember only veins have valve...
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sorry sorry this is my bad, i messed the whole thing up, here's everything in the attachement
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therefore semilunar valves ARE NOT IN THE HEART AND ARE IN VIENS ONLY FOR EXAMPLE VEINS IN THE LEG, WHEN THE SKELETAL MUSCLE PUSH ON IT SO BLOOD CAN FLOW UPWARDS, THE SEMILUNAR VALVES PREVENT BLOOD FROM GOING BACKWARDS :D
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there are semilunar valves in the heart.....between the ventricles and the aorta/pulmonary artery....
from left atrium to left ventricle is bicuspid valve, from right atrium to right ventricle is tricuspid valve.
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the valve between ventricle and aorta is called aortic valve right?
this brings me to this question, semilunar valves is one valve only? or a type of valve or what?
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it's called the atrio-ventricular valve
semilunar valves are present in all veins,apart from the aorta and pulmonary artery, hence they are a type of valve
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exactly nid404, Thanks =D
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recko? ::)
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wts da questions gonna be like tomorrow??????????
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I wish I knew :P
DO NOT TRY TO CHEAT
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recko? ::)
hahahaha hello =D
no cheating :)
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suggest the significance of the 5' and 3' endz of the two strandz of the DNA double helix?
suggest briefly why it is thought tht the arrangement of the bases in the nucleic acidz is in the form of a 'triplet code'?(3 markz)
suggest why DNA synthesis takes place in opposite directions on the two separated strandz of the double helix?
plz clear ma confusionz,me givin de paper too tmrw
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Heyy Guys
Biology Paper 2 On Friday, How Are Your Preparations & Any Doubt or Predictions Please Post Them Here To Help Everyone Out :)
i have a question myself
nov 08, first variant, last question about water
thanks :D
water molecules have a partially postive hydrogen and partially negative oxygen so the oxygen on one molecule is attracted to the hydrogen on another. this makes water molecules cohesive and thus they are trasported as a continuous column in plants.
also water hasa high specific heat capacity so the temperature doesn't change quickly.
hydrogen bonding provides surface tension so some insects can live on the surface of water.
water bodies (e.g. lakes) freeze from the top down, thus organisms that live in water don't die as the floating ice acts as an isulator.
lastly it has a high boiling point and a high latent heat of vaporization so it is a liqid over a large range of temps.
hope this helped :)
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what r the maximum marks u can lose in paper 2 to still get an A !?!??!
im basically askint h threshold .. i cant find it anywher .. =/
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usually it's around late 30s or early 40s something for an A
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usually it's around late 30s or early 40s something for an A
oo thts cool thn .. Thanks =D
gd luck!!
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not this time thoough the thhreshold is gonna be high 40's like 48-49 i bet........... it was relatively a fairly simple paper..........waddya guys think....... just good or bad.........BUT NO CHEATING......
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This paper was wayy too easy...but even nov paper was. Novs threshold was 35 :S I expect it to be much more this time....around say 43/44
But still, this paper....hahaha...I owned it ;D
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@nid404
how was it with you?
is THAT Easy? because im dead scared, just tell me if its easy or hard please. and how long?
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Variant 2 was easy as.
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i got 22 variant... it ws nt so good i guess................... mostly general............
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how about variant 1? anyonee??
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suggest the significance of the 5' and 3' endz of the two strandz of the DNA double helix?
suggest briefly why it is thought tht the arrangement of the bases in the nucleic acidz is in the form of a 'triplet code'?(3 markz)
suggest why DNA synthesis takes place in opposite directions on the two separated strandz of the double helix?
plz clear ma confusionz,me givin de paper too tmrw
this is nt in AS!!