A level Biology: Post your doubts here!

[A*****]

I think i get it now
Blood from right atrium will leak to left side so the blood entering right ventricle would be less so blood would be pumped at lower pressure in pulmonary artery not at higher pressure so the blood will enter the lungs at a lower rate and the diffusion rate of oxygen saturation of haemoglobin will be less. Therefore C.

At the same time, blood at higher pressure from the left atrium can also enter the right atrium and I guess it will have a greater chance of flowing this way bqz movement is from high to low pressure
This will increase the pressure in the right atrium
Why is this so confusing

 

[SohaibButt]

At the same time, blood at higher pressure from the left atrium can also enter the right atrium and I guess it will have a greater chance of flowing this way bqz movement is from high to low pressure
This will increase the pressure in the right atrium
Why is this so confusing

Maybe this time i get it well look when blood flow into the left atrium from the lungs it is not in high pressure so if blood do enter into the right atrium it won't affect that much am I right?

 

[Ayesha Asif333]

because of the continuous mixing of blood, there will not be a significant change in the pressure on either side of the septum. the pressure might rise of fall a little depending on the movement of blood. e.g when left atrium contracts some blood is pushed to the right and then when the right atrium contracts some amount of blood will move to the left side, thus one can conclude that the most significant affect on the circulation is that there will be reduced oxygen saturation as the concentration gradient has been disturbed.

 

[Ayesha Asif333]

because of the continuous mixing of blood, there will not be a significant change in the pressure on either side of the septum. the pressure might rise of fall a little depending on the movement of blood. e.g when left atrium contracts some blood is pushed to the right and then when the right atrium contracts some amount of blood will move to the left side, thus one can conclude that the most significant affect on the circulation is that there will be reduced oxygen saturation as the concentration gradient has been disturbed.

I might as well be wrong in my explanation. :'D It's been a long time since i last studied abt the heart.

 

[SohaibButt]

I might as well be wrong in my explanation. :'D It's been a long time since i last studied abt the heart.

No ur reason seems more valid

 

[Hisham Khan]

Guess what guys!,I found a question which is basically the same thing but with different wordings lul in 2014 paper. Btw I have memorized the question 30 to be either both 4 or both 4 and 5 cause it comes in every paper xD

 

[Ayesha Asif333]

No ur reason seems more valid

well yes,

For those still struggling in questions set for higher ability candidates, do always refer to the examiners report as just sufficient explanation is provided there for you to make sense of the answer.

 

[A*****]

Guess what guys!,I found a question which is basically the same thing but with different wordings lul in 2014 paper. Btw I have memorized the question 30 to be either both 4 or both 4 and 5 cause it comes in every paper xD
View attachment 63719

Why have u memorized it?
Sometimes the question has slightly different wording...like it asks about the number of phospholipid layers, no. of phospholipid bilayers, etc

 

[Ayesha Asif333]

Guess what guys!,I found a question which is basically the same thing but with different wordings lul in 2014 paper. Btw I have memorized the question 30 to be either both 4 or both 4 and 5 cause it comes in every paper xD
View attachment 63719

Why have u memorized it?
Sometimes the question has slightly different wording...like it asks about the number of phospholipid layers, no. of phospholipid bilayers, etc

Infact, it'll be a little more satisfying to draw and count than to recall : )

 

[Kanekii]

Infact, it'll be a little more satisfying to draw and count than to recall : )

How to do that? An example would be very much appreciated

 

[Ayesha Asif333]

How to do that? An example would be very much appreciated

It becomes very simple to sketch as all the barriers are single celled linings, the arrows drawn here are just for your understanding so can during the exam make an even simplified rough diagram.
For the no. of phospholipid layers count every line 2 times or simply double, 5 becomes 10 and 4 becomes 8.
Whereas phospholipid bilayer and cell membrane are the same thing.

 

[Kanekii]

It becomes very simple to sketch as all the barriers are single celled linings, the arrows drawn here are just for your understanding so can during the exam make an even simplified rough diagram.
For the no. of phospholipid layers count every line 2 times or simply double, 5 becomes 10 and 4 becomes 8.
Whereas phospholipid bilayer and cell membrane are the same thing.

View attachment 63721

Thanks alotttt it was really helpful.

 

[Ayesha Asif333]

Thanks alotttt it was really helpful.

Happy to help. URW ★

 

[sukasukinya]

Can someone help me with this question?

 

[Hisham Khan]

As stated stroke volume is volume of blood pumped by EACH contraction of a ventricle.
So as ventricular end-diastolic volume increases,so will the volume of blood pumped.So A and B are wrong.
but obviously volume pumped will not be proportional to volume pumped,which kinda makes sense because myogenic nature of heart isin't that perfect and power of contraction to pump blood is the same so it will be much difficult to push all the blood!.
So I would say answer is D!

 

[innovative_1]

How to do this one??

 

[Hisham Khan]

How to do this one??

I don't get it.Nor can I waste my brain cells too focus on it haha.
Funny thing is I got 37/40 in may june 14 paper where threshold for A was 26 lol and in some papers I got low where threshold were in 30s.Intresting

 

[A*****]

How to do this one??

Both of them are close between the time intervals marked with green (between 1&2 + between 3&4)
Sorry it's a bit rough but hope u understand

 

[innovative_1]

Both of them are close between the time intervals marked with green
Sorry it's a bit rough but hope u understand

Yeah i understand but what we need to do next? Like we need to find the difference in time between them?

 

[A*****]

Yeah i understand but what we need to do next? Like we need to find the difference in time between them?

No just add them for TOTAL time for which both are closed