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MEGATHREAD BMAT discussion for 2015 entry

Sorry, I misunderstood haha. I see what you've done and to be honest, it does make sense, however I think you have to approach the question like I showed to someone above. Following what you're saying would result in S having to be BB, in order to produce Bb, Bb,Bb, Bb.

But as I said above, we're treating the offspring's genotypes as independent, meaning that the probabilities are constant.

If you now read my answer above again, hopefully it might make a little more sense.

The point that I'm making is that it's a given that U must 100% be a carrier, so working on from that, one can establish the probabilities of S and T

I did treat them independently.

U - 100%, that's easy to see
T - has no conditions tied with it in the question, can be whatever it wants (BB Bb Bb bb) so 50%
S - Cannot be bb if you use the condition tied with it in the question. To allow W not to have the disease, it HAS to be either Bb or BB. Again, still treating it independently, its options are down to (BB Bb Bb).

Really can't see where I'm going wrong at all.

Reply 1781

Efemena15

4

Original post by TotalerReinfall

Yes I got that U is 100%, don't worry about that :smile:

My question was concerned with S - notice that the question also says that only R and X have the disease. This means W cannot have the disease. As R must be bb, S cannot be bb; it must be either Bb or BB to allow W to not have the disease.

Although what you're saying is correct, it still doesn't affect the probability of S. It can't

Reply 1782

Efemena15

4

Original post by TotalerReinfall

I did treat them independently.

U - 100%, that's easy to see
T - has no conditions tied with it in the question, can be whatever it wants (BB Bb Bb bb) so 50%
S - Cannot be bb if you use the condition tied with it in the question. To allow W not to have the disease, it HAS to be either Bb or BB. Again, still treating it independently, its options are down to (BB Bb Bb).

Really can't see where I'm going wrong at all.

You are correct, but it's asking for the likelihood of the genotype being Bb, so I don't think you can use your own information if you know what I mean. Arghh it's hard to explain on here and I do agree with you, it's just a bad question

Reply 1783

kpkumar1

Hi, does anyone know how to quickly do the balancing chemical equation questions? I usually skip them out in section 2 because they take a long time to do, especially if the multiples are high. I wonder if I'm missing a shortcut.

Reply 1784

username1107011

1

Original post by Efemena15

You are correct, but it's asking for the likelihood of the genotype being Bb, so I don't think you can use your own information if you know what I mean. Arghh it's hard to explain on here and I do agree with you, it's just a bad question

Yeah, in that case I just can't seem to fathom why the conditions given in the question affect the probability of U, but not S.
Oh well

Reply 1785

House MD

13

Original post by TotalerReinfall

I did treat them independently.

U - 100%, that's easy to see
T - has no conditions tied with it in the question, can be whatever it wants (BB Bb Bb bb) so 50%
S - Cannot be bb if you use the condition tied with it in the question. To allow W not to have the disease, it HAS to be either Bb or BB. Again, still treating it independently, its options are down to (BB Bb Bb).

Really can't see where I'm going wrong at all.

Original post by Efemena15

You are correct, but it's asking for the likelihood of the genotype being Bb, so I don't think you can use your own information if you know what I mean. Arghh it's hard to explain on here and I do agree with you, it's just a bad question

The thing is, the question requires you to use logic to deduce that U must be 100% (i.e. discarding the other options).

But then you're not supposed to use logic to deduce what S is?

It's inconsistent.

Also, T ought to be 66% too, since we're told that "ONLY individuals R and X have the disease". So T cannot be bb

(edited 9 years ago)

Reply 1786

username1107011

1

Original post by House MD

Also, T ought to be 66% too, since we're told that "ONLY individuals R and X have the disease". So T cannot be bb

Good point. What a mess of a question

Reply 1787

skizzle

6

Guys do we need to know what fulcrum means, or anything to do with moments (you know with the pivots) both physics related...I saw them in some of the really old papers but not sure if we need it now :/

Reply 1788

DCMed96

16

Original post by ΘTheta

Don't you mean C. 1/15 * 8/14 + 1/15*7/14*4 =6/35, not 12/35

Oh sorry, anyway just add up the two probabilities together

Posted from TSR Mobile

Reply 1789

Big Thinker

1

Does anyone wanna cry with me

Reply 1790

BrokenS0ulz

3

Original post by TotalerReinfall

Amino acids are buffers though because they contain an amine group as well as a carboxyl group, so surely it'd be C?

The official answer is E, but it would make sense if it was C if they are buffers. I suppose that at GCSE we are taught they lower pH so the BMAT will only test us on knowing they lower pH?

Reply 1791

drifter_skylight

6

Help please:
S2 2010. LAST question (27)

A car of mass 800 kg moves up an incline of 1 in 20 (this means every 20m along the road the car is gaining 1 metre in height) at a constant speed of 20m/s. The frictional force opposing the motion is 500 Newtons. How much work has been done by the car after it has moved 50 metres?

So WD = Force * displacment
Force will be resultant force after taking friction .. F - 500 will give resultant force.
displacement is 2.5 metres.
How do I convert 800 kg into a force..
and I have not used to the speed yet so I am going wrong somewhere
the right answer is 45.

Reply 1792

diseasedneckbeard

9

Original post by liass

Has the spec changed just for 2014, or was it 2013 as well? Because I read through and mades notes by the science spec, but in the past papers loads of questions come up on things which are not in the spec?

I think the most recent change was just for 2009 onwards but I can't really remember. Notably, I don't think we need to know the reactivity series or the uterus (progesterone etc.). I'm just going to practise as much as I can to cover all my bases.

------------------

Slowly improving at S2. Last 2 papers I scored 16 with a couple of stupid mistakes, which is about 5.7+.

(edited 9 years ago)

Reply 1793

AnushkasHero

4

Original post by Efemena15

When solving a quadratic equation, for example x² - 9x + 20 = 0
The numbers in the brackets have to multiply to give 20 and add to give -9. This would give (x-4)(x+5) So we know the roots are x=4 and x=-5

Therefore in the question, the product has to be +9, giving answers A or C. The roots are opposite signs to the brackets, so therefore the answer is C, because the numbers in the brackets would be negative, so the root is positive

Original post by waza96

Couldn't you do

x+y=7
xy=9

x=9/y

sub into 1st equation
(9/y)+y=7

(9+y^2)/y=7

y^2-7y+9

therefore, C

This might be wrong, but it seems right to me :smile:

Oh yeah this makes sense! All this BMAT revision today has fried my brain hahaha

Reply 1794

House MD

13

Original post by TotalerReinfall

Amino acids are buffers though because they contain an amine group as well as a carboxyl group, so surely it'd be C?

Stupid question once again.

But I guess it asks about "contributing to the change in pH"

The fatty acids will lower the pH by some amount. The amino acids will act as buffers, and therefore still affect the pH to a certain extent - maybe counterracting the change caused by the fatty acids by a bit.

So you could argue that the amino acids have also 'contributed' to the change in some way.

Reply 1795

callmemorbid

9

Original post by drifter_skylight

Help please:
S2 2010. LAST question (27)

A car of mass 800 kg moves up an incline of 1 in 20 (this means every 20m along the road the car is gaining 1 metre in height) at a constant speed of 20m/s. The frictional force opposing the motion is 500 Newtons. How much work has been done by the car after it has moved 50 metres?

So WD = Force * displacment
Force will be resultant force after taking friction .. F - 500 will give resultant force.
displacement is 2.5 metres.
How do I convert 800 kg into a force..
and I have not used to the speed yet so I am going wrong somewhere
the right answer is 45.

work out gpe by doing 800x10x2.5, which is 20kj. then do work equals force times distance, so 500x50 which is 25kj, and add the two together

Reply 1796

nk96

1

Hey guys, help for this question please.
How would you approach questions like this?

Thanks for any help, much appreciated

2011 S1, Q7

Reply 1797

skizzle

6

Guys how would you do this?

Help please guys! Is there a quick way to do this? I think it is doable, but the time it takes it just ridiculous and I'm pretty sure they would not put a question like this in without there being a much easier way to do it.

Any help is appreciated, thanks!

For reference, it's from 2011 section 1 q5