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Edexcel IAL Biology Unit 5 (WBI05) Scientific Article Discussion - June 2016

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Original post by Polpi
No he/she is asking about a respirometer not spirometer


Oh! Yeah we do not keep oxygen conc constant in that either.. Then how would liquid in manometer move?
(edited 7 years ago)
Original post by ~xSarahx~
Does anyone know any good websites where I can go over all the statistical tests? (T-test, Chi-square)


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http://biology-a2.weebly.com/unit-6.html
I used this hope it helps

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Original post by Quirky01
Why would u keep oxygen concentration constant? If u look at a spirometer trace u will see that the trace slopes downwards showing volume of oxygen decreases..we do not keep volume of oxygen constant in spirometer..we only absorb any CO2 produced 😊



@mystreet091234 Exactly, you don't keep the oxygen concentration inside the respirometer neither inside the spirometer constant, because to measure the rate of oxygen uptake or the rate of breathing or minute ventilation, you need the volume of oxygen changing.
The CO2 is absorbed by Soda lime because when you breath or during respiration , the volume of oxygen taken would be the same as CO2 released so you won't be able to measure anything
(edited 7 years ago)
Original post by Quirky01
What should be limitations for gel electrophoresis and tensile strength?
Asking u guys particularly!😊😊😊


I guess the limitations would be

( they wouldn't just bring GE alone, they would won't you to do an investigation with it)

- Difficulty to control all variable affecting the identification of DNA band sizes as the concentration of DNA fragments inside each well (I am not 100% it's correct)

- The DNA was only taken from two suspects/people

- Difficulty of proposed technique

That's what I can think of
Original post by Polpi
Btw do you know what they mean by continuous prose ? Like wrote in paragraphs and organise everything step by step ?


Yeah like writing in paragraphs and not as points
Reply 285
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Polpi
2
I FOUND SOMETHING ABOUT GEL ELECTROPHORESIS Best AnswerYou have to look at the protocol. The general migration rate depends on 1) agarose density 2) voltage 3) buffer characteristics 4) temperature (the chamber does get warmer during the run) 5) time Are you changing any of these intentionally? Probably not. The distance migrated will depend upon the length of the DNA fragment. (For circular DNA, the configuration will also matter.) In most experiments, the distance(s) will depend of the DNA fragment length(s) which will change based on the sample. ADDENDUM: As I suspected, the DNA loaded is altered so that is the independent variable. The distances the fragments travel will be the dependent variable. The charge on DNA derives from the phosphates. Since there is one phosphate per base, the charge to mass ratio is fairly close to constant. If an electric field is present, the acceleration on each fragment will be the same. The gel is a meshwork and smaller molecules move through the "net" more easily
Do you guys remember this question that came up on the optimum concentration of protease enzyme in washing powder or something?
We used a gelatin solution. What if it's a lipase or a carbohydrase? What solutions do we use then?
Reply 287
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Aimen.
7
Original post by Quirky01
What should be limitations for gel electrophoresis and tensile strength?
Asking u guys particularly!😊😊😊


limitations for gel electrophoresis would be:
Disposing off the waste is hazardous to environment as ethidium bromide is a possible mutagen.
Gels can melt during experiments.
A large tissue sample is needed to run the assays
Some DNA bands might have low intensities due to less sample or may be smeared due to poor quality of buffer!

limitations of tensile strength:
Putting weights on string without care may cause it to break.
Not all variables affecting the tensile strength can be controlled such as humidity of the surroundings.
Experimental conditions in lab are not representatives of the real conditions in forests etc.

Spoiler

Reply 288
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Aimen.
7
Original post by Polpi
Btw do you know what they mean by continuous prose ? Like wrote in paragraphs and organise everything step by step ?


All they want is join everything up. like no gaps xD I don't like the idea tho, bullets are better!
Reply 289
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Polpi
2
how can you control humidity?
Reply 290
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Aimen.
7
Original post by user179
Do you guys remember this question that came up on the optimum concentration of protease enzyme in washing powder or something?
We used a gelatin solution. What if it's a lipase or a carbohydrase? What solutions do we use then?


Carbohydrase would do starch solution and lipase would do a cup of oil maybe?
Reply 291
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Aimen.
7
In Q#3(d) presenting and analysing data.
If we include control in the table we draw, do we plot it on the graph as well?
Reply 292
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Aimen.
7
Original post by Polpi
how can you control humidity?

I believe you can't!
Original post by Aimen.
In Q#3(d) presenting and analysing data.
If we include control in the table we draw, do we plot it on the graph as well?


I believe you do, for example using 0% concentration of something you would plot it on the y-axis and join it up! :smile:
So there are certain names of things we have to remember, like:

-using orcein stain for mitosis experiment or any staining
-soda lime/sodium hydroxide for the respiration experiment or any absorption of CO2
-using benedicts for presence of glucose/reducing sugars (to red/orange colour)
-using biurets for presence of proteins (to purple colour)
-using iodine solution for presence of starch (to blue colour)

are there any more solutions and stuff we need to remember the names of?
And are these all correct?:colondollar:
Reply 295
Avatar for Aimen.
Aimen.
7
Original post by Annaaix_
So there are certain names of things we have to remember, like:

-using orcein stain for mitosis experiment or any staining
-soda lime/sodium hydroxide for the respiration experiment or any absorption of CO2
-using benedicts for presence of glucose/reducing sugars (to red/orange colour)
-using biurets for presence of proteins (to purple colour)
-using iodine solution for presence of starch (to blue colour)

are there any more solutions and stuff we need to remember the names of?
And are these all correct?:colondollar:


You could use orcein ethanoic or toluidine blue for mitosis.
KOH/NaOH or sodalime for absorbing CO2.
Knowing benedict's or fehling's for whatever is a part of chem course and not biology so knowing it is good but you can get full marks even without that!
Biurets for proteins??? :confused::eek: Never heard of this!! Do tell me if it is so!
And iodine for starch is quite common I guess!
Umm you need to know which enzyme digests what.
Btw fehling's or benedict's won't work with disaccharides !

BTW best of luck for tomorrow! x
For the daphnia experiment
when observing the daphnia under the microscope the light can affect the heart rate due to the increase in temperature
How can we control this?
Original post by Polpi
how can you control humidity?


You can't control it but you can take it into consideration
Original post by user179
Do you guys remember this question that came up on the optimum concentration of protease enzyme in washing powder or something?
We used a gelatin solution. What if it's a lipase or a carbohydrase? What solutions do we use then?


I believe you don't need to know, use information that is used in the question. For that question, it was about the clearance of a stain so you can say that a measured volume of stain is found on a piece of cloth
Original post by Aimen.
You could use orcein ethanoic or toluidine blue for mitosis.
KOH/NaOH or sodalime for absorbing CO2.
Knowing benedict's or fehling's for whatever is a part of chem course and not biology so knowing it is good but you can get full marks even without that!
Biurets for proteins??? :confused::eek: Never heard of this!! Do tell me if it is so!
And iodine for starch is quite common I guess!
Umm you need to know which enzyme digests what.
Btw fehling's or benedict's won't work with disaccharides !

BTW best of luck for tomorrow! x


Benedicts, biuret and iodine are in the gcse course, I think I saw it in a markscheme too! Good to know anyway just incase, you won't lose marks for mentioning :smile:
Biuret solution is very similar to iodine in the way it's used for testing! Just used for proteins and turns purple if present

What are the enzymes that digest what? I'm so bad with enzymes :frown: I know protease is for protein but thats it:colondollar:

Good luck to you too! x

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