Qualification > Sciences
ALL CIE BIOLOGY DOUBTS HERE !!!
Sue T:
--- Quote from: Vampire-Love4ever on May 11, 2011, 11:16:08 pm ---Doubts attached!
--- End quote ---
counting the number of cells on the grid under view gives th no. of cells per 0.04mm2 (since its th area of the grid) If less than half of the cell is in the grid, its not counted. The area 0.04 is multiplied by the depth 0.1mm to give the volume of the grid. this gives 0.004mm3. Now jus count the number of cells under view and divide by the volume (which is identical to multiplying by 250 cuz 1/0.004 = 250) to find the no. of cells per mm3 - mention doing repeats n etc...
next part - it was mentioned in the begining tht th original number of cells was 3thousand. in the table where the mean is - the column heading is thousands of cells per mm3 of culture - so ur mean of 6.2 is actually 6.2 thousand --- now for calculating th percentage increase just follow wat they said takinf th final number as ur mean value and the original number as 3 - thts it
Sue T:
--- Quote from: Vampire-Love4ever on May 11, 2011, 11:18:38 pm ---Doubt: my answer was opposite to mark scheme (marked) :S please explain!
--- End quote ---
see the thing is ur supposed 2 draw conclusions from the graph wether ther is a relationship between the fragmentation index and the conc of this CB-153 thing - now between 60 and 120 u can see a large increase and no overlap of error bars - which supports th theory that th inc in CB causes damage to the DNA - but wen u look at 120 - onwards there is a lot of overlap - so ther cod be no relationship - as in you cant really see anymore wether an increase in CB really causes damage
jus rethink this and look at th answer again - ull b sure 2 get it ;)
Sue T:
--- Quote from: Vampire-Love4ever on May 11, 2011, 11:26:01 pm ---Doubt attached!
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organism 1 has the antibody for antigen X so one line shows up in front of it - organism 2 has th antibody for both antigens so u c 2 lines ( a line forms because a ppt appears due 2 th antigen meeting its antibody.
Sue T:
--- Quote from: Vampire-Love4ever on May 11, 2011, 11:27:26 pm ---Doubt attached! Please explain Point 11!
--- End quote ---
see to ensure reliability you have 2 tell them: carry out the experiment in the same area when u repeat it - cuz like other areas myt have some more pollen in the air - its jus 2 produce more reliable results
Sue T:
--- Quote from: Vampire-Love4ever on May 11, 2011, 11:50:29 pm ---Doubt attached!
Why can't we use a water bath to maintain the temperature? ? ? :S
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i think its cuz it myt affect th humidity which decreases th rate of transpiration and affects the rate of movement up the stem ;)
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