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AQA BIOL1 Biology Unit 1 Exam - 16th May 2011

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Reply 640
Avatar for liviaaa
liviaaa
Original post by DoaaK
lungs are lobe like structures, the trachea is supported by ring cartilages to prevent the airways collapsing during inspiration and the muscles are lined with ciliated epithelium and goblet cells, which produce mucus to trap the microorganisms and dirt to prevent it entering the blood system by diffusing through the alveoli, the trachea then divide into two divisions, one in each lung, it's structure is similar to the trachea but the ring cartilages are thinner. this then divides into the bronchioles which has muscle that contracts to control the volume of air entering the alveoli, the alveoli are the site of gas exchange and is made out of collagen and elastin that allows it to recoil so air can passively expirate via the springing and recoil of the alveoli.



what's the stucture of the epithelial cell?


Thanks :smile:

Just like any ekaryotic cell I guess, membrane, nucleus, cytoplasm..
We're going to need a big post-exam discussion thread tomorrow
Original post by Tericon
Can anyone help me with q5diii? Don't understand why there needs to be two antibodies? Same with pregnancy test.

Also the plate is washed, i don't understand what on earth the enzyme has to do with the antibodies and antigens, and have't all the antigens been washed away?!....Really confused by this...

Anyone help please? :biggrin:

http://store.aqa.org.uk/qual/gce/pdf/AQA-BIOL1-W-QP-JUN09.PDF


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.
(edited 12 years ago)
How are lungs adapted to gas exchange?

Explain Humoral and Cell mediated Response?

EACH 5 MARKS
Reply 644
Avatar for Rickesh
Rickesh
Test for non reducing sugar !!!
Reply 645
Avatar for Jubilee~
Jubilee~
4
can someone explain vaccines & monoclonal antibodies :/ so confusing
Is it just me that is finding Immunity hard and everything else really easy?
Reply 647
Avatar for Jubilee~
Jubilee~
4
Original post by Rickesh
Test for non reducing sugar !!!


add benedicts reagent, if the colouring stays blue you add hydrochloric acid (i think) to break the disaccharide into it's monosaccharides. Then you add sodium hydrogen carbonate (i think) which because it's an alkaline will neutralise the acid.
Then re-test with benedicts reagent and if a non reducing sugar is present, the colour will go from blue to orange/brown
Reply 648
Avatar for Jubilee~
Jubilee~
4
Original post by nasira372
Is it just me that is finding Immunity hard and everything else really easy?


thats me :confused: im just gonna memorise it now.
i have a feeling it'll come up and i don't want to go into the exam with any skeletons in my closet
Original post by ??????????????????

Original post by ??????????????????
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.


Antibody has specific shape which is complemetary to that antigen gets you the mark?
Original post by Rickesh
Test for non reducing sugar !!!

You would add benedicts solution and boil it for a while. If it was blueish then there are no reducing sugars present. This is so confirm that it is not a reducing sugar. Then you would have to hydrolyse it by adding dil HCl (with heat?) and then neutralise it with NaOh (why do you neutralise it anyway?) before adding benedicts again. If it goes brick red it is positive so shows that it was a non reducing sugar.
Original post by Jubilee~
can someone explain vaccines & monoclonal antibodies :/ so confusing


Done a briefish one above.
Reply 651
Avatar for Rickesh
Rickesh
Original post by BeejTheone
How are lungs adapted to gas exchange?

Explain Humoral and Cell mediated Response?

EACH 5 MARKS


Lungs have alveoli that increase the surface area to volume ratio allowing for effcient gas exchange. The alveoli have thin walls so have a short diffusion pathway, so oxygen can diffuse rapidly. The alveoli are moist, again for effiient gas exchange. The alveoli have a good supply of blood to maintain the concentration gradient to allow oxygen to diffuse down its concentration gradient efficiently.

Humoural is basically the B-cells that produce memory cells, and plasma cells that produce memory cells. So if the foreign antigen was to re-enter the body again, the memory cells would remember the antigen so there wouldnt be a primary response i.e. the person would not feel ill, there would be a quicker response so th person doesnt feel ill. Cell-mediated is basically how the T-cells work, i.e. they attach themselves to the antigens creating a antibody antigen complex?!?!? and then they stimulate the b-cells. Also the T killer cells kill the cell by various ways e.g. poking holes in the cell making it burst?

Mark what you think I would have got out of 5 for each and where I could improve please !! :smile: thanks
Original post by BeejTheone
How are lungs adapted to gas exchange?

Explain Humoral and Cell mediated Response?

EACH 5 MARKS


Lungs are adapted for gas exchange because they have many alveoli walls which provide a large surface area so faster diffusion. Also the walls of the alveoli are really thin so the diffusion pathway is really short so even faster diffusion. The concentration gradient is maintained by ventillation of air and circulation of blood which believe it or not, makes the diffusion gradient even faster....
Reply 653
Avatar for Rickesh
Rickesh
Original post by Jubilee~
add benedicts reagent, if the colouring stays blue you add hydrochloric acid (i think) to break the disaccharide into it's monosaccharides. Then you add sodium hydrogen carbonate (i think) which because it's an alkaline will neutralise the acid.
Then re-test with benedicts reagent and if a non reducing sugar is present, the colour will go from blue to orange/brown


Spot on !! Nice one
Original post by BeejTheone
Antibody has specific shape which is complemetary to that antigen gets you the mark?


The enzyme bit was a different question.

Basically the enzyme is used to find the pathogen.
Ie tumour markers. They might use a drug. The enzyme is complimentry in shape no the antibody and the antibody is complimentry in shape to the antigen. If the antibody binds to the antigen and the enzyme binds fo the antibody you can locate the tumour.
Reply 655
Avatar for Jubilee~
Jubilee~
4
Original post by BeejTheone
How are lungs adapted to gas exchange?

Explain Humoral and Cell mediated Response?

EACH 5 MARKS


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) :s-smilie:
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.
Original post by BeejTheone
How are lungs adapted to gas exchange?

Explain Humoral and Cell mediated Response?

EACH 5 MARKS


are these questions u made up
or are these questions from the exam
Original post by Rickesh

Original post by Rickesh
Lungs have alveoli that increase the surface area to volume ratio allowing for effcient gas exchange. The alveoli have thin walls so have a short diffusion pathway, so oxygen can diffuse rapidly. The alveoli are moist, again for effiient gas exchange. The alveoli have a good supply of blood to maintain the concentration gradient to allow oxygen to diffuse down its concentration gradient efficiently.

Humoural is basically the B-cells that produce memory cells, and plasma cells that produce memory cells. So if the foreign antigen was to re-enter the body again, the memory cells would remember the antigen so there wouldnt be a primary response i.e. the person would not feel ill, there would be a quicker response so th person doesnt feel ill. Cell-mediated is basically how the T-cells work, i.e. they attach themselves to the antigens creating a antibody antigen complex?!?!? and then they stimulate the b-cells. Also the T killer cells kill the cell by various ways e.g. poking holes in the cell making it burst?

Mark what you think I would have got out of 5 for each and where I could improve please !! :smile: thanks


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;
Original post by BeejTheone
How are lungs adapted to gas exchange?

Explain Humoral and Cell mediated Response?

EACH 5 MARKS


The lungs contain numerous alveoli. This increases the surface area over which diffusion of oxygen into the blood can take place, thus increasing the rate of diffusion.
The alveoli also have thin walls which means that diffusion takes place over a short distance, and so fast diffusion takes place.
Uuum a concentration gradient is also maintained by the movement of an external medium i.e. blood
The lungs are also moist which means that oxygen can be dissolved and diffuse into red blood cells in capillary.
Lungs are ventilated which maintains a concetration gradient
Original post by hahaff

These are previous questions from past papers

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