AQA BIOL1 Biology Unit 1 Exam - 16th May 2011

Nice answer

1 Many alveoli / alveoli walls folded provide a large
surface area;
2 Many capillaries provide a large surface area;
3 (So) fast diffusion;
________________________________________________
4 Alveoli or capillary walls / epithelium / lining are thin /
short distance between alveoli and blood;
5 Flattened / squamous epithelium;
6 (So) short diffusion distance / pathway;
7 (So) fast diffusion;
________________________________________________
8 Ventilation / circulation;
9 Maintains a diffusion / concentration gradient;
10 (So) fast diffusion;

Cant find the second answers MS. But looks right to me

Lungs have many alveoli which produce a large surface area for gas exchange. The alveoli is also thin to reduce the diffusion pathway. (cant think of anything else so do correct me lol)

Cell mediated immunity -
Pathogen is taken up by a phacocyte
the phagocyte will then display the antigens from the pathogen on it's surface
a certain t-helper cell will have a complimentary receptor to fit the antigen on the surface of the pathogen.
This will activate other T helper cells to divide into clones by mitosis.
These clones will -
Stimulate phagocytosis
Stimulate B Cells to divide
Develop into memory cells which will prevent any future contact with the same pathogen
And kill the pathogen...


Cell mediated - (i hatethis one)
A Certain B cell will display the antigen of the pathogen on it's surface
A T- cell will then have receptors complimentary to this antigen.
When it binds to the antigen it activates the B cells to divide into clones by mitosis
it will develop into two types -
plasma cells which have a short life span but they make a large number of antibodies to kill the pathogen.
And into memory cells which will circulate the blood ready to make plasma cells if it comes into contact with the same pathogen again...


is that right? just wrote down what i remember.

I'm on it!
Mainly cos I've done that question a long time ago but need to remember it D:

for III it's because if you don't wash it out you can still have sone left so if the antigens are not present you still get a positive result as they are stil there. Enzymes are related to the antibodies/gens because it's monoclonal. To see if they are infected, the enzyme is used. If it binds to the antigen it is infected.

OKay thankss How does emphysema cause shortness in breath ?

OKay thankss How does emphysema cause shortness in breath ?

Okay so here's a question.


Explain how the Cholera bacteria causes diarrhea in the patients
- mention water potential etc.

Ok, still confused (I'm a special brand of stupidity :P)

I get steps 1 and 2 detailed in the question. They make perfect sense, what i don't get is:

1. Why carry on? They've established the sample contains the antigen and so person is infected right?
2. why use another antibody?
3. The plate is washed at step 4, so what remains on the plate? antibodies are stuck to plate right? but haven't all the antigens gone?
4. How on earth can an enzyme be complementary to an antigen?!

Thanks

Reduced elasticity; Lungs cant fully inflate, so less oxygen diffues through to the blood.

Thicker walls, less gas exchange surface..

Alveolar damages reduced Sa...

Coz of all of these, Less respiration as less oxygen reaches respiring tissue so you're tired

Somewhere along the lines of that?

yepp thats right !

Okay so here's a question.


Explain how the Cholera bacteria causes diarrhea in the patients
- mention water potential etc.

How much wood would chuck norris chuck if chuck norris could chuck wood?

How much wood would chuck norris chuck if chuck norris could chuck wood?