A level Biology: Post your doubts here!

[My Name]

Question 3 c says: "Describe the role of haemoglobin in the transport of oxygen and carbon dioxide."

You seem to be answering a different question

Question 6: A few grammatical mistakes but your answer seems good to me. However, it seems like you have made three points, whilst the question has 4 marks. The mark scheme shows the first general statement you made as one mark. Next, you made one statement for each table, so you got two from that.
Each table has two rows ( 2 marks) so you could have made two more points. (or one would've been enough)

Sorry I meant question 3 d part ii

If possible can you highlight the mistakes...
So what else should I mention?
So your saying on more comparison from the table?
Btw the ER says:


Ty!

 

[qwertypoiu]

Y

Sorry I meant question 3 d part ii

If possible can you highlight the mistakes...
So what else should I mention?
So your saying on more comparison from the table?
Btw the ER says:
View attachment 55381

Ty!

Your answer:
"The gases diffuse down the concentration gradient. In the pulmonary artery the pO2 i slower than in the alveolous in the alveolus it is 13.87 kPa. This oxygen diffuses into teh blood from the alveolus.When the artery that carries oxygen rich blood reaches near the respiring tissue there the pCO2 in capillary network is low at the arteriol end.Thus CO2 diffuses out of the tisues and into the blood."

The (very simple) errors (that don't even matter):

• In the beginning, it's better to say gases diffuse down their concentration gradient, instead of the.
• In the pulmonary artery the pO2 i slower - should be is lower
  
• You said in the alveolus twice.
• That sentence should simply say: "In the pulmonary artery, the partial pressure of oxygen is lower than in the alveolus, where it is 13.87 kPa."
• The not teh.

And some more later on but I don't feel good listing such obvious errors that were probably just caused by a rush in typing!

So to the marks:

first mark:


You got this one.

Next four marks:


You got two of these marks, by making comparison statements.

I was just saying you could get another one, for example by saying pCO2 in blood at lungs is higher than alveolar pCO2, thus causing CO2 to diffuse out of blood into lungs.

 

[qwertypoiu]

Sorry I meant question 3 d part ii

If possible can you highlight the mistakes...
So what else should I mention?
So your saying on more comparison from the table?
Btw the ER says:
View attachment 55381

Ty!

Oh and your question 3:
Your answer:
"At high altitude pCO2 would be lower than at seas level which means that Hb would be less saturated.If haematrocrists increase whihc is more number of RBCs
the RBCs can compensate for the low pO2."

It's a good answer. I'm sure you meant pO2 at first, instead of pCO2.
Also, near the end you say the higher number of red blood cells are compensating for low pO2, I think it's better to say the higher number is compensating for low volume of oxygen transported due to low saturation of haemoglobin. Hope that helps

 

[My Name]

Y

Your answer:
"The gases diffuse down the concentration gradient. In the pulmonary artery the pO2 i slower than in the alveolous in the alveolus it is 13.87 kPa. This oxygen diffuses into teh blood from the alveolus.When the artery that carries oxygen rich blood reaches near the respiring tissue there the pCO2 in capillary network is low at the arteriol end.Thus CO2 diffuses out of the tisues and into the blood."

The (very simple) errors (that don't even matter):

• In the beginning, it's better to say gases diffuse down their concentration gradient, instead of the.
• In the pulmonary artery the pO2 i slower - should be is lower
  
• You said in the alveolus twice.
• That sentence should simply say: "In the pulmonary artery, the partial pressure of oxygen is lower than in the alveolus, where it is 13.87 kPa."
• The not teh.

And some more later on but I don't feel good listing such obvious errors that were probably just caused by a rush in typing!

So to the marks:

first mark:

View attachment 55393
You got this one.

Next four marks:
View attachment 55394

You got two of these marks, by making comparison statements.

I was just saying you could get another one, for example by saying pCO2 in blood at lungs is higher than alveolar pCO2, thus causing CO2 to diffuse out of blood into lungs.

Thank you very much!
Ahehe typos
Alright thanks!

Oh and your question 3:
Your answer:
"At high altitude pCO2 would be lower than at seas level which means that Hb would be less saturated.If haematrocrists increase whihc is more number of RBCs
the RBCs can compensate for the low pO2."

It's a good answer. I'm sure you meant pO2 at first, instead of pCO2.
Also, near the end you say the higher number of red blood cells are compensating for low pO2, I think it's better to say the higher number is compensating for low volume of oxygen transported due to low saturation of haemoglobin. Hope that helps

Yes,yes I obviously meant pO2.
It did help Thank you for your time. May Allah reward you for this!

 

[qwertypoiu]

Thank you very much!
Ahehe typos
Alright thanks!

Yes,yes I obviously meant pO2.
It did help Thank you for your time. May Allah reward you for this!

You're welcome.
Please ask more I'll answer as soon as I can

 

[My Name]

You're welcome.
Please ask more I'll answer as soon as I can

Yes,In sha Allah I might post some tomorrow.
JazakAllah Khair

 

[nehaoscar]

Can someone please explain what i need to know about the Hardy–Weinberg principle?
I'm not sure what it is and what all i need to know for my A2 exam in summer 2016...

The syllabus says:
explain how selection, the founder effect and genetic drift may affect allele frequencies in populations
use the Hardy–Weinberg principle to calculate allele, genotype and phenotype frequencies in populations and explain situations when this principle does not apply

So if someone could please give me notes to cover up what the syllabus wants please?

 

[hekato]

This is one of the syllabus of 2016 which got pretty me confused. Can anybody explain this?

d) describe the breakage of glycosidic bonds in polysaccharides and disaccharides by hydrolysis, with reference to the non-reducing sugar test

What degree of explaination involved in that particular statement?

 

[My Name]

For 4 marks Id get 2 for this point,right?

The nitrate ions are very soluble in water.When flood hits,the flood water takes up all the nitrates and the soil is infertile.
Lack of nitrates will result in poor growth.

I dont get the first point from MS!

MS

 

[My Name]

I dont get the second point!

 

[qwertypoiu]

View attachment 55710
I dont get the second point!

I am guessing that the second point refers to scavengers. They eat dead animals left in the wild. An example of a scavenger would be an ostrich. They eat dead animals that have already been decomposed by the bacteria. So now how do you assign a trophic level to a scavenger? In this case, the energy source was freely available on the floor, already decomposed for them, and they directly took that energy.
Usually, energy from dead animals goes into plants as nutrients, THEN the energy goes into animals when they eat plants.
We usually say the first trophic level are the plants. In a food chain without plants being involved, like the scavenger case, first trophic level may be the scavenger itself.
Btw I'm guessing all this.

 

[My Name]

I am guessing that the second point refers to scavengers. They eat dead animals left in the wild. An example of a scavenger would be an ostrich. They eat dead animals that have already been decomposed by the bacteria. So now how do you assign a trophic level to a scavenger? In this case, the energy source was freely available on the floor, already decomposed for them, and they directly took that energy.
Usually, energy from dead animals goes into plants as nutrients, THEN the energy goes into animals when they eat plants.
We usually say the first trophic level are the plants. In a food chain without plants being involved, like the scavenger case, first trophic level may be the scavenger itself.
Btw I'm guessing all this.

Yes,thank you!
That makes sense.

 

[Eygption student 2]

how to get grade a star in a level bio
I got grade A in AS bio 9700

 

[My Name]

how to get grade a star in a level bio
I got grade A in AS bio 9700

Congratz for your A in AS! I also hope I can get an A!

Study well and practice past papers,I guess that's it.
Do you need notes for A2?

 

[Eygption student 2]

send notes if it is useful

 

[My Name]

send notes if it is useful

Ill give you the links to the notes thread.You can decide for yourself if you find them useful or not. Here:
https://www.xtremepapers.com/community/threads/biology-p4-section-b-solved-2002-2013.33080/
https://www.xtremepapers.com/community/threads/biology-9700-paper-4-past-paper-notes.41234/

 

[Eygption student 2]

ok thanks how many topics should I finish every month

 

[Eygption student 2]

for example in next month do u have online help like youtue

 

[My Name]

ok thanks how many topics should I finish every month

Welcome.It depends on how much time you take to absorb things.
The A2 topics < what I think> are lengthy.So if you finish 2 to 3 chapters thoroughly in a month,that would be an accomplishment! Thats just an opinion.

for example in next month do u have online help like youtue

Right now I can only think of one.You can check this :
Ms Cooper's Cambridge A level Biology > https://www.youtube.com/channel/UC2yOqKblASJzqMZfRL0DbYA/playlists
The letters after K are all A2 chapters.I think not all the topics are there yet.Something is better than nothing,I suppose.

Btw if you do find any good site for A2 Bio share the link here.Please and thank you!

 

[Eygption student 2]

can u mention which chapters should I finish in September