My Biology BYA1(AQA) Answers Please correct and comment

OP

Thanks alot. We'll I live in england btw.

Reply 21

wellp i see. I hope other people here put up complete versions of the questions in numbers 3-7. at least il try mark down my answers, and hope i dont lose as much as 15 marks, cuz as far as im concerned looking at your answers and the probable correct answers ive already lost 3 marks, i might lose more marks and ill be deeply troubled. I want those A's badly. hehehe.imma got o sleep now. nyt nyt

Reply 22

OP

Tell me the questions and Ill answer them, the thing Is I forgot the questions.

Reply 23

well i forgot the questions too. hope somebody can post the questions here cuz i am really bothered with my answers. im such a sad person right now

Reply 24

animaluvva

nasht

And about the stroke volume, i think it refers as to how much blood is pumped out, so you will need to subtract maximum value to minimum value. like 130-60 or something like that. I think that's why they placed a small space below the question to work out the stroke volume, but hey i could be wrong.

I thought the same thing - because the graph started at 60 not 0, I did 130-60....but I'm no Science teacher so I'm not saying that thats necessarily right, lol

Reply 25

I thought the same thing - because the graph started at 60 not 0, I did 130-60....but I'm no Science teacher so I'm not saying that thats necessarily right, lol

im gonna try and look that out in the net right now.
T_T, im really bothered by the other questions not posted in this topic... BTW the chemistry test was easy

Reply 26

animaluvva

cool - let us know know what u come up with!

Reply 27

KaosLisa

Well you've done alot better than me, i found it pretty much really hard. I got pretty much same answers as you just more basic in alot less detail, looks like im resitting in June :frown:

Reply 28

OP

Hey thanks! And the stroke volume is 130-60 :frown:

Well done you guys :P

Reply 29

vinny221

11

Godsize

Hey thanks! And the stroke volume is 130-60 :frown:

Well done you guys :P

Checked the Na+ question today with bio teacher and you are wrong. The graph was basically of the same concept as the photosynthesis graphs and limiting factors. As rate of Na+ increases, so does rate of diffusion up toa point where it levels off.

Reply 30

OP

.... the graph would have gone totally straight and then leveled off if that was the case.
Intrinsic protiens cause the limitation as Na+ ions pass through them, if there were infinite intrinsic protiens the rate of diffusion would increase forever as conc. increased. The ONLY thing limiting the rate of diffusion therefore was, the number of protiens in the membrane, as they can only accomodate for a specific number of ions in a certain time, the others have to remain un-diffused until the other ion passes through, then it can diffuse. In the start parts of the graph the protiens could accomodate for the small increase, but as the conc. increased it slowly limited the rate until one point at which it simply cannot allow any more Na+ ions to pass through. Print this, and show it to your teacher.

Reply 31

oxymoron

7

Hmm ... I think the biology teacher may be correct in this case.

Compare to photosynthesis: If you plot a graph of rate of photosynthesis against concentration of CO2, it starts of by increasing then it levels off (same as the graph you got in your exam ... note these graphs are NOT totally straight then level off, they curve slightly). This is because to begin with CO2 is limiting, so increasing it's concentration increases the rate ... but as you get to the point where CO2 is in excess, other things take over (eg light intensity) and CO2 is no longer a limiting factor.

In your question ... at very low conc of Na+ the concentration of Na+ IS limiting (consider putting only one ion in ... the concentration of ions is so low that the diffusion rate is limited ... add an extra ion and the diffusion rate increases). So at low concentrations of Na+ ... "an increase in Na+ conc increases the rate"
When Na+ conc increases to the point where the graph levels off, their conc is no longer limiting because other factors (eg proteins in the membranes as you are talking about) are limiting the diffusion rate instead.

I do see what you're trying to say, but still think at very low concentrations, the ion concentration will be limiting. Have you asked your own teacher by the way?

Reply 32

OP

Photosynthesis is a totally different story as a hundred things are limiting it (light, c02 etc.)

"an increase in Na+ conc increases the rate" thats what you said, so it's not limiting is it?, It's increasing the rate.

The question wasnt about very low concentrations, infact it went right till the part where the graph leveled off. In the start it was totally straight. it then curved inward slightly and went straight. Where it started curving the ions had to 'wait' until the other ions passed through until they could, and at one point the protiens Cannot accomodate for more ions, unlike the case at where the graph begins to curve. Over there the delay in passage causes the rate to decrease. Na+ ions cant be limiting the rate of diffusion, as increasing concentration difference increases diffusion.

Reply 33

oxymoron

7

Godsize

"an increase in Na+ conc increases the rate" thats what you said, so it's not limiting is it?, It's increasing the rate.

If an increase in Na+ conc increases the rate, it means that Na+ conc is the thing stopping the rate from increasing ... ie it is limiting as you need to add more ions before the rate can increase.

If the question was talking about the horizontal bit of the graph, then yes, at this point protein channels are the limiting factor (or at least something other than Na+) :smile:

Reply 34

OP

Look,

In the question, The concentration of Na+ ions is increasing already increasing. They are asking whats limiting the diffusion across the surface as the conc. increases so how can you say the concentration of Na+ ions is limiting it then?.. the concentration of the ions INCREASES ANYWAY across the graph and they're asking what limits the graph between that range of INCREASE.

i put conc of ions

well we will just have to wait and see about that concentration problem. I guess, it really is the transmembrane proteins thats limiting the rate. hmm, godsize i think you are 90% correct hehehe. Well if thats the case i already lost 5 marks i presume. I dont wanna lose any more marks at all. hahaha. but anyway about the stroe volume of the heart, yeah im so sure that you have to subtract 130 with 60, but im not saying its 100% sure. But i do hope it is, come to think of it, they gave a working space after the question just enough for the subtraction thingy, hehehe, and those 6 point questions, oh my gosh, i just do hope ive placed averything in it.

what was the last question btw?

OP

It was the heart one

For Q 2 (b) I think I just put 0.11 instead of 0.11 micrometers - WILL I MISS OUT ON A MARK FOR THIS?

Reply 39