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BIOLOGY PAPER 34 MAY/JUNE 2017

SohaibButt

SohaibButt

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darks said:
hey what significant figures to use when calculating actual lengths for e.g in O/N/16/33.....Q2 C)i...
If two plant cells are touching in a diagram... and no cell wall separation is visible ? we do not separate the cell walls in plan diagram?
Also if nucleus visible seems to be touching cell membrane in animal cell, do we draw just a single line to represent that region?
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ig two because one is nuclear
darks said:
View attachment 62222
Here.. a bunch of cells "image length" measured, then using the scale.. lengths are found.. Do we write in whole numbers??!
Also the mean in next step 1 d.p? Metallic9896 techgeek hey sorry for tagging you guys.. Just wanted to know the answer if you know... i got no teacher to ask to :p
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YEA IT'S REALLY TRICKY ONE :'(
 
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Metallic9896

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darks said:
View attachment 62222
Here.. a bunch of cells "image length" measured, then using the scale.. lengths are found.. Do we write in whole numbers??!
Also the mean in next step 1 d.p? Metallic9896 techgeek hey sorry for tagging you guys.. Just wanted to know the answer if you know... i got no teacher to ask to :p
Click to expand...

Use the rules we use in Physics, i.e., keep the significant figures equal to the least accurate value used in the calculation. Measure the lengths by your ruler, they'd be accurate to 1 mm. Something like 5.4 cm would be written as 54 mm or 54000 micrometer. Everything should be in 2 sig fig including the mean as far as I can tell. The mean CAN be one sig fig higher though too.

Magnification would be calculated as:

the length of the scale bar on your paper in micrometers / 308

Let's say it showed up as 2 cm so you'd get it by 20000 / 308 = 64.9350649 and make it 65 or 64.9 at max.

I'd then get actual lengths by dividing the measured lengths in micrometer by 65 or 64.9 and write the answer to two sig figures. Mean would be by adding all of em and dividing by 5 and also to two sig fig.

Or am I dumb and I'm missing something? lol
 
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darks

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Metallic9896 said:
Use the rules we use in Physics, i.e., keep the significant figures equal to the least accurate value used in the calculation. Measure the lengths by your ruler, they'd be accurate to 1 mm. Something like 5.4 cm would be written as 54 mm or 54000 micrometer. Everything should be in 2 sig fig including the mean as far as I can tell. The mean CAN be one sig fig higher though too.

Magnification would be calculated as:

the length of the scale bar on your paper in micrometers / 308

Let's say it showed up as 2 cm so you'd get it by 20000 / 308 = 64.9350649 and make it 65 or 64.9 at max.

I'd then get actual lengths by dividing the measured lengths in micrometer by 65 or 64.9 and write the answer to two sig figures. Mean would be by adding all of em and dividing by 5 and also to two sig fig.

Or am I dumb and I'm missing something? lol
Click to expand...
You are a life saver!! Thanks a lot! :D
 
D

darks

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SohaibButt said:
What abt antibiotic last question?
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Were your measurements similar?
antibiotic one i ruled the graph lines, next part value 110mm2. The last part was from AS syllabus. So i wrote the action of antibiotic on bacterial cell wall, and it bursting as a result. Most mistakes according to me, were made in 1st q. table. People did not take two time readings for average, or did not write color for the 2% solution.
 
SohaibButt

SohaibButt

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darks said:
Were your measurements similar?
antibiotic one i ruled the graph lines, next part value 110mm2. The last part was from AS syllabus. So i wrote the action of antibiotic on bacterial cell wall, and it bursting as a result. Most mistakes according to me, were made in 1st q. table. People did not take two time readings for average, or did not write color for the 2% solution.
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Oh yea well it's fine i think 1 mark deduct
 
DeadbeatCIE

DeadbeatCIE

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Paper was relatively easy, I got the microscope question alright. The first question however i got 6% as the conc for U, forgot to mention colour in the table. Will i lose too many marks or will it be fine. What can the gt be expected to be?
 
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darks

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DeadbeatCIE said:
Paper was relatively easy, I got the microscope question alright. The first question however i got 6% as the conc for U, forgot to mention colour in the table. Will i lose too many marks or will it be fine. What can the gt be expected to be?
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6% is good as long as it fits the trend of your table. 1 mark for the color. I think ZERO and 2% concentration had 240+seconds thing. 2% was pale pink. while , 0 was purple.
 
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darks

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DeadbeatCIE said:
I got more around 150 s for 4% and i did include 0% and i got more than 240 for 0% and 2%.
Things are starting to look pretty good only if i hadn't forgotten to include color in the table
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SohaibButt said:
It was more than 240
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i got for 2% and 0% more than 240..
and for rest i got below 36 seconds... The 2% as well just turned pale pink pretty fast in like 100 seconds but was stuck there for more than 240 seconds
 
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