A level Biology: Post your doubts here!

[My Name]

When a cell is placed in a solution that has low water potential, the cell's water content is lost to the surroundings. So the cell shrinks. Should be A.
Perhaps you were confused by D. A cell would actually burst when placed in high water potential solution, since water would move into the cell and make it expand, till it bursts (if it doesn't have a cell wall Eg animal cell)

Haha yes I marked D. :/

 

[My Name]

20: nitrogenous bases are read as 3. Meaning 3 nitrogenous bases codes for one amino acid. Therefore 12/2 = 6, 6/3= 2. Ans is 2 x 10^3
23: Divide first time you get 100% hybrid DNA (as mentioned in the question). Divide twice you get 50% hybrid and 50% containing only 14N. Divide 3 times, you will get 25% of hybrid and 75% containing only 14N. What about 4th times? there will be about 12.5% of hybrid DNA and about 82.5% DNA containing of 14N. You can try to draw the nuclear division diagram like i attached to you earlier so you can have an image about it.
24: I think the volume does not change is because the contraction is very fast, so the volume of ventricle is somehow remain the same ... (sorry I am not sure with this )
30: 1 is caused by the tension of water, forming a negative pressure in the xylem vessel. 3 is somehow relates to the statement 1.
15: Not sure about this too...

Anybody please help out with question 15!! and question 24 as well

Hope you can understand my explanation and correct me if i have made any mistake.

Thanks for your help.
I made the diagram like you said and YAY I got it right! Thank you so much!

 

[My Name]

http://zafarsulehrinotes.wikifoundry.com/page/MCQs+PREPARATION
^ This might help some people.Check it.
In sha Allah I might use it for testing myself.

 

[My Name]

Dude I have been trying to download them from yesterday! And everytime after waiting for almost 30 min they say that its failing!!

Alhamdulillah I was able to download it.
I will try to attach the file...let me know if you can download it.

You can also check these links,but be sure to read teh whole post because I also mentioned the mistakes..
https://www.xtremepapers.com/commun...st-your-doubts-here.9858/page-260#post-913723
https://www.xtremepapers.com/commun...st-your-doubts-here.9858/page-260#post-913737
https://www.xtremepapers.com/commun...st-your-doubts-here.9858/page-260#post-913752
https://www.xtremepapers.com/commun...st-your-doubts-here.9858/page-260#post-913784

^ AS paper 1 Notes by My Name read full posts and note down the mistakes!

 

[My Name]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_12.pdf
question

24
15 so They are all random.What do they mean by random here?

Please and Thank you!

 

[SadiaMaryam]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w11_qp_12.pdf
question

24
15 so They are all random.What do they mean by random here?

Please and Thank you!

I think random here means the 'obvious' movement of particles as described by the kinetic theory, molecules moving from high to low conc. to minimize the collisions etc.
....tricky question
Let me look at the other one.

 

[My Name]

I think random here means the 'obvious' movement of particles as described by the kinetic theory, molecules moving from high to low conc. to minimize the collisions etc.
....tricky question
Let me look at the other one.

I actually marked teh one in which all are NOT random :/
Okay

 

[SadiaMaryam]

I actually marked teh one in which all are NOT random :/
Okay

If u have the book by Mary Jones, Richard Frosbery...there is a very good explanation of question like this on page 120 (SAQ 9.1)
tell me if u dont have that book or if u still can't understand

 

[My Name]

If u have the book by Mary Jones, Richard Frosbery...there is a very good explanation of question like this on page 120 (SAQ 9.1)
tell me if u dont have that book or if u still can't understand

Let me read it.

 

[My Name]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_w12_qp_12.pdf
question 15
30 I just cant seem to remember this graph and when valves and stuff!
33 What about 2?
34

 

[My Name]

Give me your email, if you want them, I think this is the only way to send tem!

Did you try what I told you to?
Btw are they notes for P1 or just general notes?

 

[My Name]

http://papers.xtremepapers.com/CIE/...nd AS Level/Biology (9700)/9700_s15_qp_11.pdf
when I open this file the pictures seem to be missing!
Can anyone take a screenshot of the diagrams of question 3 and 6.

 

[Iris Dylan Lane]

 

[Iris Dylan Lane]

 

[My Name]

Yess I did, and this happens everytime!
They are general notes that my teacher bought online, it helps you in solving all the three papers 1,2and 3!
View attachment 57553

Oh hmm that never happened to me though.

 

[My Name]

View attachment 57551

View attachment 57552

Thanks alot.
Just imagine I get blank space instead of these. o.o

 

[qwertypoiu]

Thanks alot.
Just imagine I get blank space instead of these. o.o

I saw you asked that diffusion question somewhere I forgot where but anyhow here's the answer:

Diffusion occurs as A RESULT OF random movements. Molecules move randomly, colliding with each other, which eventually leads to general NET movement down the concentration gradient.
Osmosis is the same as diffusion, but just with H2O molecules. It happens AS A RESULT OF random movements.
Facilitated diffusion is just the same as diffusion, it occurs passively due to concentration gradient, as a RESULT of random movements. The only difference with diffusion is that it is regulated by channel proteins and carrier proteins

 

[My Name]

I saw you asked that diffusion question somewhere I forgot where but anyhow here's the answer:

Diffusion occurs as A RESULT OF random movements. Molecules move randomly, colliding with each other, which eventually leads to general NET movement down the concentration gradient.
Osmosis is the same as diffusion, but just with H2O molecules. It happens AS A RESULT OF random movements.
Facilitated diffusion is just the same as diffusion, it occurs passively due to concentration gradient, as a RESULT of random movements. The only difference with diffusion is that it is regulated by channel proteins and carrier proteins

Okay thank you.
Did you read this in the coursebook?

 

[bakhita]

I've got this book for A'Level Biology...Is it enough to cover my 2016 syllabus?
http://www.goodreads.com/book/show/3168879-as-level-and-a-level-biology

 

[My Name]

I've got this book for A'Level Biology...Is it enough to cover my 2016 syllabus?
http://www.goodreads.com/book/show/3168879-as-level-and-a-level-biology

This is the old edition so the answer is No.This is because that there have been changes in syllabus,some topics have been removed for example Ecology and some have been added fro example a bit more about telomeres and stuff.

The latest edition is this one:http://assets.cambridge.org/97811076/36828/cover/9781107636828.jpg
But my teacher said she is not completely satisfied with it either.
I am currently using the 3rd edition and I was thinking of taking pictures of the pages that are not in my book from a friends book. Ive seen the 4th edition it is quite similar to the 3rd but obviously changes are there.