AQA BIOL1 Biology Unit 1 Exam - 16th May 2011

If a pathogen enters the body describe the events that take place with the T and B cells....

Reply 562

Original post by Rickesh

If a pathogen enters the body describe the events that take place with the T and B cells....

Cell Mediated immunity goes something like this.
1) A pathogen invades a host and is taken in by a phagocyte.
2) The phagocyte then presents antigens from the pathogen on it's surface.
3) It is then specifically recognised by a Receptor protein on a T Cell
4) This results in induced mitosis and differentiation of the T cell into :
a) T Killer cells=kill the infected cells
b) T helper cell which help in Humorla immunity
c) Memory Cells to prevent recurring infection of the SAME pathogen
d) Stimulates phagocytosis

Humoral Immunity is like this
1)A pathogen invades a host.
2) The antigens of the invading pathogen are then taken up by B cells.
3) They are then presented on their surface
4) T helper cells then help process the antigen and result in induced mitosis
5) PLasma cells are created which secrete antibodies to destroy the pathogen (This is the primary response)
6) Memory cells are made which prevent recurring infection.

Reply 563

Original post by Rickesh

If a pathogen enters the body describe the events that take place with the T and B cells....

This is specific response. After pathogens present the antigens on its surface, T cell with the complementary antigen will bind to these antigens and are activated once it binds. It divides in to killers cells and also releases substances that activate B cells. B cell has antibodies, once antibodies binds to complementary antigen and is activated. divides into memory cells and plasma cells. Plasma cells mass produce the specific antibodies to overcome the pathogen

Reply 564

Original post by reaperguy

Cell Mediated immunity goes something like this.
1) A pathogen invades a host and is taken in by a phagocyte.
2) The phagocyte then presents antigens from the pathogen on it's surface.
3) It is then specifically recognised by a Receptor protein on a T Cell
4) This results in induced mitosis and differentiation of the T cell into :
a) T Killer cells=kill the infected cells
b) T helper cell which help in Humorla immunity
c) Memory Cells to prevent recurring infection of the SAME pathogen
d) Stimulates phagocytosis

Humoral Immunity is like this
1)A pathogen invades a host.
2) The antigens of the invading pathogen are then taken up by B cells.
3) They are then presented on their surface
4) T helper cells then help process the antigen and result in induced mitosis
5) PLasma cells are created which secrete antibodies to destroy the pathogen (This is the primary response)
6) Memory cells are made which prevent recurring infection.

Yepp thats right ! Your turn to ask me :smile:

Reply 565

Original post by BeejTheone

This is specific response. After pathogens present the antigens on its surface, T cell with the complementary antigen will bind to these antigens and are activated once it binds. It divides in to killers cells and also releases substances that activate B cells. B cell has antibodies, once antibodies binds to complementary antigen and is activated. divides into memory cells and plasma cells. Plasma cells mass produce the specific antibodies to overcome the pathogen

good stuff :smile:

Reply 566

liviaaa

Original post by swiftylol

Wtf is endorsement? That book has a few mistakes including where it says Internal intercostal muscles are used for inhaling :colonhash:

I use steve potter books, chief examiner and that :cool:

That's the book I use, it's good for some stuff, like it mentioned the tubercles in the 5 marker in Jan 11 where people seem to be saying the other didn't. However, it misses out courtship behaviour for unit 2 completely!

Reply 567

Original post by Rickesh

If a pathogen enters the body describe the events that take place with the T and B cells....

^ Also a great answer xD

Reply 568

crazycake93

13

Original post by emmaaa65

i think you just do

4.17 - 0.17 = 4

then 4/4.17 X 100 = 95.92% ???
or you do 4/0.17 X100 but that would give you 2352.94 % which seems too big.. i dunno
im rubbish at maths

(4.17-0.17/0.17) x 100 = 2352%

Reply 569

Original post by Rickesh

Yepp thats right ! Your turn to ask me :smile:

Describe the role of enzymes in the digestion of carbohydrates

Reply 570

Original post by BeejTheone

^ Also a great answer xD

huh? lol Want to do Q/A?
during cell centrifugation, why is the sample homogenised?

Reply 571

Original post by Rickesh

huh? lol Want to do Q/A?
during cell centrifugation, why is the sample homogenised?

to break open the cells

Reply 572

Why do we use an isotonic solution?

Reply 573

Tericon

8

Can anyone help me with this, from Jan 2010

Calculate the ratio of the mass at the start to the mass at the end for the disc
placed in the 0.60 moldm–3 sodium chloride solution.

Start: 23.7 end: 21.9

I know what the answer is, but how'd you get to it? And also, i really don't get ratios full stop, is this always how you'd tackle a ratio question?

The answer is 1.08 and just be taking 21.9 from 23.7, you get 1.8....is that just a coincidence? Or is that what you do with ratio question, take smaller from larger?

Thanks :smile:

Reply 574

Original post by reaperguy

Describe the role of enzymes in the digestion of carbohydrates

Would they ask this sort of question? I thought they would only ask it for starch? What's your model answer for it?

Reply 575

Original post by reaperguy

Describe the role of enzymes in the digestion of carbohydrates

Food is physically broken down by the teeth. The salivary glands produce amylase that breaks down the starch (for example) into maltose. In the stomach the HCL denatures the amylase enzyme, so it can no longer function. The pancreas produces pancreatic juice which contains amylase, which further breaks down the starch into maltose. In the small intestines, an enzyme called maltase breaks down the maltase to glucose which is absorbed by the blood, through the whole co-transporter business with sodium etc??

What is the test for proteins?

Reply 576

Original post by Tericon

Can anyone help me with this, from Jan 2010

Calculate the ratio of the mass at the start to the mass at the end for the disc
placed in the 0.60 moldm–3 sodium chloride solution.

Start: 23.7 end: 21.9

I know what the answer is, but how'd you get to it? And also, i really don't get ratios full stop, is this always how you'd tackle a ratio question?

The answer is 1.08 and just be taking 21.9 from 23.7, you get 1.8....is that just a coincidence? Or is that what you do with ratio question, take smaller from larger?

Thanks :smile:

You divide. to get ratio

Reply 577

Original post by reaperguy

Why do we use an isotonic solution?

To prevent osmotic processes occurring, so cells do not become flaccid or turgid

How do you test for lipids?

Reply 578

301lw

does hydrolysis require atp? i know condensation does?

Reply 579