A level Biology: Post your doubts here!

[Sadi66]

q23 q24 may 2012 p12

 

[Sadi66]

P12 may 2012 q32 pls explain

 

[Sadi66]

P12 may 2012 q1 explain

 

[hizirofaki]

https://www.xtremepapers.com/community/threads/biology-mcq-questions-here.41118/

 

[Heba A.Moety]

When enzymes are inactive do their Hydrogen bonds break distorting the shape of it?Can someone explain the complete effect of temperature on enzyme activity i.e what bonds break if the enzyme's inactive(though I think bonds are not broken during inactivity) and when the temperature is increased above normal, the vibration of the enzyme 1st breaks H bonds and in the end the disulfide bonds right?

well inactivity is due to the low kinetic energy at low temp. so both the substrate and the enzyme move about very slowly and so almost no collisions occur and the rate of reaction drop but no bonds are broken and the shape of the enzyme is not distorted it and it can regain its activity once u increase the temp. again... and yes, at high temp h bonds break first due to strong vibration then the disulfide bonds this makes the enzyme lose its specific tertiary st. and its active site's shape no longer becomes complementary to the substrate and this effect is irreversible

 

[My Name]

Hey everyone!
I thought I should share some notes I made while solving paper 1.
I know you might know most of this but I hope it helps you for last minute revision.
( If incase you find any mistake let me know as soon as possible. Btw these notes are according to some questions I solved so there might be more answers for something and i might not have mentioned.)

Enjoy

 

[Studydayandnight]

Guys, how we do solve this??

I NEED to do well enough to get atleast a 30 in paper 1 :'( which seems almost impossible! -_-

How do we solve the 4th one?

 

[My Name]

TRANSPORT IN MAMMALS
EDIT:There is a mistake in the notes
"What does tissue fluid contain?
Platelets and protein concentration low as compared to plasma But NO phagocytes"

The tissue fluid is almost identical to the composition of plasma.However, it contains less proteins molecules than plasma as they are too large to escape through the tiny gaps.
Although RBCs are not present some WBCs may squeeze through.

 

[My Name]

IMMUNITY

There were two mistakes in these

-The correct answer would be like this
Active natural- reaction in the body to infection

Active artificial- reaction following vaccination

Passive natural- by antibodies passing through placenta

Passive artificial- following injection of antibodies in serum

-the action of a phagocyte when a pathogen is encountered is supposed to be like this:
endocytosis → phagocytic vacuole formation → digestion by lysosome enzymes → exocytosis

 

[qwertypoiu]

Hey everyone!
I thought I should share some notes I made while solving paper 1.
I know you might know most of this but I hope it helps you for last minute revision.
( If incase you find any mistake let me know as soon as possible. Btw these notes are according to some questions I solved so there might be more answers for something and i might not have mentioned.)

Enjoy

Thank you

 

[My Name]

INFECTIOUS DISEASES
Which disease is not likely to be passed directly from parent to child?
The answer to this is Malaria!

 

[qwertypoiu]

There is no need to start a separate thread this one is perfect ask your questions here. Start a separate one for discussion don't discuss papers here.
And please take screenshot of questions you'll get more responses that way..
I personally can't be bothered to open a specific paper just to help others, but I'm willing to try help if the picture is already uploaded...
I'm sure others feel the same way.

 

[My Name]

Thank you

Welcome
Check my latest post it has Infectious

 

[qwertypoiu]

TRANSPORT IN MAMMALS

In your notes it says:

"What does tissue fluid contain?

Platelets and protein concentration low as compared to plasma But NO phagocytes"

Are you sure? Why would there be no phagocytes. I think maybe you meant no red blood cells.

BTW I see you put a lot of effort into it (typing it all out) thanks again!

 

[My Name]

In your notes it says:

"What does tissue fluid contain?

Platelets and protein concentration low as compared to plasma But NO phagocytes"

Are you sure? Why would there be no phagocytes. I think maybe you meant no red blood cells.

BTW I see you put a lot of effort into it (typing it all out) thanks again!

Oopsee I completely forgot to change that.
There won't be any RBC but some WBC can squeeze through.I myself had a doubt about whether phagocytes will be there or not.
Thank you btw for reminding me! I'll edit that post ASAP.
Thank you it took a lot of time,but I didn't EXACTLY type it all I copied the question from past paper ( but obviously added some things).
Best of Luck!

 

[hizirofaki]

INFECTIOUS DISEASES

u r awesome appreciate he effort u r putting thx u r helping a lot

 

[hizirofaki]

the*

 

[My Name]

u r awesome appreciate he effort u r putting thx u r helping a lot

Thank you Welcome
Check above posts as well they have notes for other topics.
Best of Luck!

 

[hizirofaki]

u r awesome appreciate he effort u r putting thx u r helping a lot

btw from which year to which ?

 

[My Name]

btw from which year to which ?

Sorry I myself am not sure about that because I made them while solving topic wise papers( that's the reason why the notes aren't THAT much).