How to justify apparatus used for A level biology

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#1
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#1
I did practical 9 yesterday and I’m meant to write why I have used the apparatus I used such as thermometer and stopwatch.
How am I meant to describe why? My first thought was used a thermometer because it gives you an accurate measurement .. what else am I suppose to say ?

@reality check
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Reality Check you are very good at biology a level help please
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#3
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(Original post by hopefulDocc)
Reality Check you are very good at biology a level help please
Remind me what practical 9 is - I don't teach the specification any longer.
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#4
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thermometer - measure temperature? gives an accurate quantitative value?
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#5
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#5
(Original post by Reality Check)
Remind me what practical 9 is - I don't teach the specification any longer.
Investigation of the effect of temperature on respiration of yeast using methylene blue which gets reduced to turn from blue to colourless .
my homework was basically . Why did I use the apparatus I did ? And justify the methods I used.
i have no idea where to start and how to approach this
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#6
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(Original post by hopefulDocc)
Investigation of the effect of temperature on respiration of yeast using methylene blue which gets reduced to turn from blue to colourless .
my homework was basically . Why did I use the apparatus I did ? And justify the methods I used.
i have no idea where to start and how to approach this
OK - thanks. Yes, I know that practical now.
So, if you're investigating the effects of temperature, you need some way of measuring temperature - hence the apparatus choice of thermometer. However, the marks come in not just saying 'I used a thermometer because I needed to measure temperature' but being more specific about the scale of the thermometer. Thermometers can have a wide scale, from -50°C to 200°C or a very narrow scale, like a human body temperature thermometer which goes from about 35-41°C. Which do you think you'd be best to use for this experiment? What range of temperatures would you predict you will need to measure, given you're measuring enzymatic activity? And note that the narrower the range, the more accurate the thermometer is - so using one with a small range appropriate to the experiment allows you to make more accurate measurements. Does that make sense?

Stopwatch - again, you're measuring an experiment that is basically a rate - an enzyme rate. Rates are obviously amount of product per unit time, so you need a way of measuring time. Just like the thermometer, think about what sort of accuracy you need and justify your choice. Do you need to measure to the nearest 1000th of a second (and, practically, could you do this 'by hand)? If not, what sort of accuracy do you think is warranted for this experiment.

I know that in practice you'll just be given one type of thermometer and one type of stopwatch to actually do the experiment at school, but part of justifying your choice of apparatus involves examining things like scale, resolution etc. So, do this for all the apparatus you've chosen:

1. What do you need to measure?
2. What apparatus exists to measure this quantity?
3. Justify which scale/size apparatus is appropriate to the experiment, or the predicted measurements you'll be making.
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#7
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#7
(Original post by Reality Check)
OK - thanks. Yes, I know that practical now.
So, if you're investigating the effects of temperature, you need some way of measuring temperature - hence the apparatus choice of thermometer. However, the marks come in not just saying 'I used a thermometer because I needed to measure temperature' but being more specific about the scale of the thermometer. Thermometers can have a wide scale, from -50°C to 200°C or a very narrow scale, like a human body temperature thermometer which goes from about 35-41°C. Which do you think you'd be best to use for this experiment? What range of temperatures would you predict you will need to measure, given you're measuring enzymatic activity? And note that the narrower the range, the more accurate the thermometer is - so using one with a small range appropriate to the experiment allows you to make more accurate measurements. Does that make sense?

Stopwatch - again, you're measuring an experiment that is basically a rate - an enzyme rate. Rates are obviously amount of product per unit time, so you need a way of measuring time. Just like the thermometer, think about what sort of accuracy you need and justify your choice. Do you need to measure to the nearest 1000th of a second (and, practically, could you do this 'by hand)? If not, what sort of accuracy do you think is warranted for this experiment.

I know that in practice you'll just be given one type of thermometer and one type of stopwatch to actually do the experiment at school, but part of justifying your choice of apparatus involves examining things like scale, resolution etc. So, do this for all the apparatus you've chosen:

1. What do you need to measure?
2. What apparatus exists to measure this quantity?
3. Justify which scale/size apparatus is appropriate to the experiment, or the predicted measurements you'll be making.
DAMN teach me biology sensei!
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#8
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#8
(Original post by shohaib712)
DAMN teach me biology sensei!
hahaha

If you ever need help or advice with something, start a thread and quote me in
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#9
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(Original post by Reality Check)
hahaha

If you ever need help or advice with something, start a thread and quote me in
Thanks will do! Actually could you explain how low/freezing temperatures affect enzymes in enzyme controlled reactions? IDK my textbook doesnt include that it only mentions about high temps and how that denatures the enzymes functions.
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#10
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#10
(Original post by shohaib712)
Thanks will do! Actually could you explain how low/freezing temperatures affect enzymes in enzyme controlled reactions? IDK my textbook doesnt include that it only mentions about high temps and how that denatures the enzymes functions.
Sure - is this A level?

EDIT- can you start a new thread for this please and quote me in - it's more helpful for other people rather than put lots of topics in the same thread. Thanks
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#11
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#11
(Original post by reality check)
sure - is this a level?
yaasss! (ocr a)
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#12
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(Original post by shohaib712)
yaasss! (ocr a)
OK we'll do it here and I'll get the thread split.
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#13
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Do you do A/AS chemistry at all? I want to lead you to the answer, rather than just give it to you - this will be much more useful to you in the long run.
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#14
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(Original post by Reality Check)
Do you do A/AS chemistry at all? I want to lead you to the answer, rather than just give it to you - this will be much more useful to you in the long run.
Yes and sure I would prefer that
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#15
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#15
(Original post by Reality Check)
OK - thanks. Yes, I know that practical now.
So, if you're investigating the effects of temperature, you need some way of measuring temperature - hence the apparatus choice of thermometer. However, the marks come in not just saying 'I used a thermometer because I needed to measure temperature' but being more specific about the scale of the thermometer. Thermometers can have a wide scale, from -50°C to 200°C or a very narrow scale, like a human body temperature thermometer which goes from about 35-41°C. Which do you think you'd be best to use for this experiment? What range of temperatures would you predict you will need to measure, given you're measuring enzymatic activity? And note that the narrower the range, the more accurate the thermometer is - so using one with a small range appropriate to the experiment allows you to make more accurate measurements. Does that make sense?

Stopwatch - again, you're measuring an experiment that is basically a rate - an enzyme rate. Rates are obviously amount of product per unit time, so you need a way of measuring time. Just like the thermometer, think about what sort of accuracy you need and justify your choice. Do you need to measure to the nearest 1000th of a second (and, practically, could you do this 'by hand)? If not, what sort of accuracy do you think is warranted for this experiment.

I know that in practice you'll just be given one type of thermometer and one type of stopwatch to actually do the experiment at school, but part of justifying your choice of apparatus involves examining things like scale, resolution etc. So, do this for all the apparatus you've chosen:

1. What do you need to measure?
2. What apparatus exists to measure this quantity?
3. Justify which scale/size apparatus is appropriate to the experiment, or the predicted measurements you'll be making.
Thanks loads. One quick question though soz soz . In improvements I mentioned that we could use an electric water bath instead due to haand made one is prone to heat loss and the need to control it by adding more hot water decreases the accuracy , is that correct ?
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#16
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#16
(Original post by hopefulDocc)
Thanks loads. One quick question though soz soz . In improvements I mentioned that we could use an electric water bath instead due to haand made one is prone to heat loss and the need to control it by adding more hot water decreases the accuracy , is that correct ?
Yes - that's fine. You need to be able to accurately control the temperature during the experiment, and a water bath is the most accurate way of doing this.
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#17
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(Original post by shohaib712)
Yes and sure I would prefer that
Good - that helps enormously. So, in chemistry, what factors can determine the rate of a reaction?
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(Original post by Reality Check)
Good - that helps enormously. So, in chemistry, what factors can determine the rate of a reaction?
presence of cataylst, temperature, concentration/pressure of reactants
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#19
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(Original post by shohaib712)
presence of cataylst, temperature, concentration/pressure of reactants
Brilliant. And thinking of temperature, what happens when you lower the temperature of the system?
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(Original post by Reality Check)
Brilliant. And thinking of temperature, what happens when you lower the temperature of the system?
less KE, therefore less collisions with correct orientation, therefore lower rate of reaction?
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