AQA BIOL1 Biology Unit 1 Exam - 16th May 2011

Could someone explain to me how to work out the serial dilutions question from the Jan 11 paper?

The student made up all the sodium chloride solutions using a 1.0 mol dm-3 sodium
chloride solution and distilled water.
Complete the table to show how he made 20 cm3 of a 0.2 mol dm-3 sodium chloride
solution.


Volume of 1.0 moldm-3 sodium chloride solution:
Volume of distilled water:

I don't know how to do it???

someone ask another question?

Discuss the ethical issues with the use of vaccinations. (Straight off the spec.)

Gonna have to guess at this one, dont have a clue:

Some may argue that when a ahigh enough proportion of the population is immune from vaccines, herd immunity means the rest do not need vaccines.
Animal testing is required to make the sure the vaccine is safe, and animals are sometimes required to produce vaccines.
Some parts of the world do not have access to vaccines, and drugs companies only produce the vaccines for wealthiy countires.

Please provide the proper answer...

What happens during the primary response? and then during secorndary response to foreign pathogen?

Use of animals? Ethically acceptable?
Side effects?
Health risks - are the public going to take a risk in trying out a new vaccine
Religious opt outs?!?

:|

Describe how the immune system responds when a pathogen invades a body cell.

When it first enters the body a non-specific response will occur. This includes inflammation, so the capilaries become more permeable and more white blood cells can escape. A fever will also occus, raising the body temperature which causes damage to the pathogens. Phagocytosis will also occur - chemicals called medicators are released which attract phagocycotic cells, they engulf bacteria closing them in phagosomes. Lysosomes then migrate towards it and secrete hydrolytic enzymes and digest the microorganism.

If not destroyed then the specficic response..

Hey everyone, can anyone help me with this question, don't need to know the answer, just how to work it out. Conversion into micrometres is the troubling bit:


This diagram shows the cell magnified 1000 times. Calculate the actual length of the
cell between points P and Q. Give your answer in micrometres. Show your working.

Observed size is 89mm

Thanks

Hey everyone, can anyone help me with this question, don't need to know the answer, just how to work it out. Conversion into micrometres is the troubling bit:


This diagram shows the cell magnified 1000 times. Calculate the actual length of the
cell between points P and Q. Give your answer in micrometres. Show your working.

Observed size is 89mm

Thanks

i hate those questions!! :/ xxx

Which paper is this?

We know that the equation for magnification is as follows:

Magnification = size of image / size of object

We need to find the actual length of P and Q. The actual length is represented by the object. So re - arranging the equation you get:

Size of object = size of image / magnification

Always remember that the image and the object should be in the same units, in this case, micrometres.

So size of object = 89 000 um / 1000 = 89 um

As everyone seems to agree on the fact that immunity will come up, would anyone care to summarise the topic. General or great detail, up to you but I think it will be good revision and it would help me a lot as its my weakest topic. Topic 1,2 and 3 are really easy. 4 and 5 average. 6 is the hardest in my opinion and am really worried after reading this thread

This is what I know so far (not much I know):

physical barriers: skin is very thick.
Chemical barriers: oils on skin, hydrochloric acid in stomach, tears, urine, mucus in lungs.

2nd line of defence is called the inflammatory response. It is controlled by white blood cells called phagocytes. It is non specific. The process is called phagocytosis. These are the steps of phagocytosis:

1) phagocyte engulfs the pathogen
2) pathogen is enclosed into a vesicle/phagosome
3) Lysosomes in the phagocyte contain digestive enzymes which hydrolize the pathogen

If the inflammatory response does not kill the pathogen, then it is left to the specific immune response called humoral and cellular

The cellular is to do with T cells and the humoral response is to do with B cells. B cells secrete antibodies whereas T cells do not.

Hi all,

I just want to ask. I have been doing some of the old 'legacy' spec past papers and I am unsure about how much we should know about digestion. DO we need to know about endo/exo peptidases? Is it only Starch digestions that we need to know for the new spec?
Because I am not 100% sure

As everyone seems to agree on the fact that immunity will come up, would anyone care to summarise the topic. General or great detail, up to you but I think it will be good revision and it would help me a lot as its my weakest topic. Topic 1,2 and 3 are really easy. 4 and 5 average. 6 is the hardest in my opinion and am really worried after reading this thread

This is what I know so far (not much I know):

physical barriers: skin is very thick.
Chemical barriers: oils on skin, hydrochloric acid in stomach, tears, urine, mucus in lungs.

2nd line of defence is called the inflammatory response. It is controlled by white blood cells called phagocytes. It is non specific. The process is called phagocytosis. These are the steps of phagocytosis:

1) phagocyte engulfs the pathogen
2) pathogen is enclosed into a vesicle/phagosome
3) Lysosomes in the phagocyte contain digestive enzymes which hydrolize the pathogen

If the inflammatory response does not kill the pathogen, then it is left to the specific immune response called humoral and cellular

The cellular is to do with T cells and the humoral response is to do with B cells. B cells secrete antibodies whereas T cells do not.

Ive revised solely from the CGP along with Markscheme revision. Do you think this will be enough in order to get an A. I pretty much understand everything in a simplistic manner but I'm not sure if the CGP lacks vital pieces of information having read some over complicated answers in this thread??
p.s everything answer in the markscheme for the previous 4 papers on AQA website is in the CGP!