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AQA BIOL1 Biology Unit 1 Exam - 16th May 2011

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Can anyone please help with this...its maths and my brain just shuts down:

Calculate how much risk is increased by smoking 25 a day compared with not smoking at all:

Not smoking: 0.17 25 a day: 4.17

For any increase/decrease equation remember the following:

(Difference/original) x 100

So in this case:

(4.17 - 0.17) / 0.17 x 100 = 2353 % (What? So high? :redface:

)

Reply 201

Tericon

Original post by nasira372

If your asking in % change then its the difference / original * 100
So in this case its 4/0.17 * 100 = 2352.9 % increased chance

If your asking how many times higher it is, you just divide 4.17 by 0.17 = 24.53
24.53 Times higher risk.

Hope that helps, correct me if im wrong

Looks good to me thanks, I was thinking all you had to do was take 0.17 from 4.17....but thats just the difference :redface:

I hate that we have to cope with bits of maths in Biology :tongue:

Thanks everyone, there isn't enough rep to go around :biggrin:

(edited 12 years ago)

Reply 202

emmaaa65

Original post by animal*nature

Hi guys I was just wondering for the non reducing sugar test when you add sodium hydrogen carbonate why do you have to add it slowly ? Doubt it will come up bit you never know with aqa ! Good luck guys x

maybe to make sure you dont OVERneutralise it making it become an alkaline solution instead of neutral?

Reply 203

nasira372

Original post by emmaaa65

i think you just do

4.17 - 0.17 = 4

then 4/4.17 X 100 = 95.92% ???
or you do 4/0.17 X100 but that would give you 2352.94 % which seems too big.. i dunno
im rubbish at maths

You divide the 4 by 0.17, not 4.17
95% increase seems a little low because 100% doubles the figure to 0.34 which is nowhere near 4.17
2352.94% is correct

(edited 12 years ago)

Reply 204

Sparkly-Star

Original post by Insanity514

Why is the Secondary immune response much QUICKER and GREATER than the primary immune response?

Because in the secondary response memory cells are already developed, so they will be able to recognize the antigens on the pathogens straightaway. Whereas in the primary response they will have no memory cells developed against the pathogen so they have to go through the whole process of T - cells and B - cells placing the antigens of the pathogen on their cell - surface membranes in order to produce plasma and memory cells which is a slower process.

Reply 205

jones_wise

On the specification, we are required to know 'The essential difference between humoral and cellular responses as shown by B cells and T cells.' As a revision exercise, would anyone be willing to give a short summary of what we would be required to know? Many thanks.

Reply 206

Sparkly-Star

Original post by emmaaa65

maybe to make sure you dont OVERneutralise it making it become an alkaline solution instead of neutral?

Yeah that's a good point cos you would want to check the pH with pH paper as you're doing it. :smile:

(edited 12 years ago)

Reply 207

nasira372

Heres a quick question

How do ventillation and circulation maintain a difference in concentration

Reply 208

animal*nature

Original post by Tericon

Would like to know answer to that too, as you seem to know about that can i pick your brains? :tongue:

So with non-reducing, if its a positive result, it could be reducing still....why is this? Why does reducing test have to be done to rule out it being a reducing?

I suppose with non reducing test it could still be a reducing sugar but that is why you do the reducing sugar test first to prove that it it is not a reducing sugar heat it with benedicts reagents and it will stay blue.
To prove it is a non reducing sugar add hcl to hydrolyse any disaccharides into it's constituent monosaccharides and then add Sodium hydrogencarbonate to neutralise and retest with benedicts you will see a red ppt If non reducing sugar is present for example sucrose hope that helps xx

Reply 209

und

People are revising for this when there are two English exams looming ahead of them before Biology? :eyeball:

I'm leaving revision for this 'til Wednesday!

Reply 210

Limitless

Original post by und

People are revising for this when there are two English exams looming ahead of them before Biology? :eyeball:

I'm leaving revision for this 'til Wednesday!

What exam are you on about this is AS Level Unit 1 biology. The exam is first thing tomorrow morning.

Reply 211

jones_wise

Original post by und

People are revising for this when there are two English exams looming ahead of them before Biology? :eyeball:

I'm leaving revision for this 'til Wednesday!

This exam is tomorrow.....

Reply 212

Sparkly-Star

Original post by Tericon

Would like to know answer to that too, as you seem to know about that can i pick your brains? :tongue:

So with non-reducing, if its a positive result, it could be reducing still....why is this? Why does reducing test have to be done to rule out it being a reducing?

This is because some mono/disaccharides will reduce Benedict's reagent and some won't. So by doing the reducing sugars test (mainly to do with monosaccharides) you can be sure that there are no reducing sugars present because it doesn't reduce Benedict's reagent. By doing the non - reducing sugars test (mainly to do with disaccharides) you hydrolyze the non - reducing sugar into monosaccharides. These monosaccharides may well be reducing sugars so if it does reduce Benedict's reagent this time round you know that a non - reducing sugar was present in the original sample.

I hope that makes sense... sort of. :redface:

Reply 213

Sparkly-Star

Original post by nasira372

Heres a quick question

How do ventillation and circulation maintain a difference in concentration

Ventilation brings in air with a high conc. of oxygen and removes air with a low conc. of oxygen. Circulation removes blood with low conc. of oxygen and pumps around blood with high con. of oxygen... something like that. :redface:

Reply 214

animal*nature

Explain how the products of carbohydrate digestion are absorbed Into the blood (5)

Reply 215

und

Original post by jones_wise

Original post by Limitless

What exam are you on about this is AS Level Unit 1 biology. The exam is first thing tomorrow morning.

Original post by jones_wise

This exam is tomorrow.....

Oops, sorry! :colondollar:

I'm talking about the Unit 2 and 3 exams on Thursday. I thought they were all on the same day...

Reply 216

Limitless

Original post by und

Oops, sorry! :colondollar:

I'm talking about the Unit 2 and 3 exams on Thursday. I thought they were all on the same day...

Unit 2 exam is the following week on thursday.

Reply 217

liviaaa

Original post by und

Oops, sorry! :colondollar:

I'm talking about the Unit 2 and 3 exams on Thursday. I thought they were all on the same day...

Unit 2 is the Thurday after.

Reply 218

jones_wise

If we were asked to define monoclonal antibodies, do you think this would be sufficient: a type of antibody that comes from cells clones from a single B cell. ?