AQA BIOL1 ~ 14 May 2012 ~ AS Biology

Add benedicts reagent to the substance and gently heat. If there is a change in colour to brick red reducing sugar is present.

I nee help on this question. Can you please try and answer it.
Why is a vaccine given more than once?

I dont know if this is right, but I would say.
A vaccine is a dead or weakened form of a pathogen that stimulates the production of antibodies and memory cells, so if you have a vaccine more than once, if you come into contact with the antigen, the more vaccines you have, the more b memory cells so the faster the response of b memory cells producing b plasma cells, and more antibodies are produced.

Something along those lines I think. :/ x

I's give 5/5 for the first one. Practically identical to mine :P
2/2 for the next and 4/4 for the last one (but i'd make sure i'd write exactly what atheroma was, a fatty plaque build up, just so they know that you do know your stuff) well done.

1. (is this unit 2) Scary question, erm..... I'd say something like. Cellulose is made to long straight unchained beta-glucose molecules joined together with hydrogen bond forming cross-bridges. It forms microfibrils and therefore provides strong rigidity and stops plant cell walls from bursting but exerting inwards pressure?? :/ 2/2 well done

2. Active transport is against a concentration gradient, facilitated diffusion is down a concentration gradient. Active transport is an active motion (requires energy in the form of ATP) whereas facilitated diffusion is passive (requires no energy)..? 2/2 on a roll

3. You have your co-transport of glucose and sodium through protein channel. Then your Na+/K+ pump (which lowers the sodium concentration in cell, allowing the co-transport to take place). Your lipid soluble molecules will pass through the phospholipid bilayer and your water soluble substances will pass through your intrinsic proteins. Water moves via osmosis from a high to low water potential. You have simple diffusion from a high to a low concentration and finally active transport of substances against a concentration from a low to a high concentration, using carrier proteins and energy in the form of ATP. I'm not even going to bother highlighting this, you got like 10 out of 5! Great answer

I dont know if this is right, but I would say.
A vaccine is a dead or weakened form of a pathogen that stimulates the production of antibodies and memory cells, so if you have a vaccine more than once, if you come into contact with the antigen, the more vaccines you have, the more b memory cells so the faster the response of b memory cells producing b plasma cells, and more antibodies are produced.

Something along those lines I think. :/ x

Yay thanks. I'll highlight in bold where you get the marks in your answers. And sorry about the first question, didn't realise it was unit 2, but as you're doing unit 2, good practice anyway

You can tell I did the cell surface transport questions yesterday. haha
&& congrats on your 10A*s at GCSE you geek! (only joking.. i'm only jealous, haha :P) x

Not even really started unit 2 revision yet. Probably will do on Thursday or friday after i've got my worst ones out of the way x

Lol, thanks I don't even know what happened when I was doing my GCSEs! Bio2 revision, that seems like a good plan, might do the same. Just imagine, it will all be over in a few weeks ... until next year

Hi, please could someone help me on the immunity section of unit 1? I really dont understand the difference between cellular and humoral response???
thanks

Dont remind me!!
2 weeks today and i've done all mine. Cannot wait.. but dreading these next 2 weeks!!

Still, i'm going to do a plan for the rest of today:
- get all mark schemes re-written and refreshed
- do most booklets by tonight..
- re-read notes and text book.
- leave all past papers for tomorrow.. thats when i will really need them (even though i've done them millions of times)
- start r.s revision again...

^^ might actually try and stick to this for once

Hi, please could someone help me on the immunity section of unit 1? I really dont understand the difference between cellular and humoral response???
thanks

Yeah sure.
Cellular (or cell mediated) response is coordinated by the T lymphocytes. This involves the whole cell attacking the infected cell. They also produce chemicals which aid B lymphocyte cloning, encouraging the phagocytes to engulf the clumped pathogen. Cytotoxic T cells are also produced by mitosis which kill infected cells by punching holes in the membrane, so the cell is freely permeable. Memory cells are also produced by the first exposure to the antigen.

Humoral response is when the phagocytes present the antigen on their surface. There are B lymphocytes in the body which recognise and bind onto the antigen. This type of specific cell clones itself by mitosis. The clones turn into two types of cells: plasma cells which secrete antibodies rapidly and memory cells which remember the shape of the antigen so a faster immune response can be initiated on second exposure.

Sorry for the wordy answer, but it covers the main aspects of what you need to know

Thanks that really helped, all the revision books I own either dont have enough detail or too much!

To be honest i was revising this with a friend over Xbox live (yea weird) according to my friend he said that:

T Cells are involved with cellular response, this takes part in the cells (also remember T cells come from the thymus) and mainly involve processes with antigens.

B cells are associated with Humoral response where "humor" is a medium of fluid eg the blood. it is mainly with antibodies.

Not sure if that was what you were asking but this is what i found out

EDIT: the person's explanation above mine about it is much better

I know what you mean! The best thing to do in that case would be to find a question on it in a past paper and learn the mark scheme answer, as that probably covers everything you could be asked on it.

If we were given a question on Asthma... what do you think the mark points would be ?
All I have written is
- Asthma attack narrows airways
- Air in alveoli not replaced as efficiently
- Difference in concentration lower so rate of diffusion is lower.

What about the histamine..? etc.
Anyone think of more important mark points.. :/ x

If we were given a question on Asthma... what do you think the mark points would be ?
All I have written is
- Asthma attack narrows airways
- Air in alveoli not replaced as efficiently
- Difference in concentration lower so rate of diffusion is lower.

What about the histamine..? etc.
Anyone think of more important mark points.. :/ x

as far as i know you've said all marking points, i think the mast cells/histamines and mucus bits are just extra information although i'm not entirely sure.

Nope those three are the marking points available, I don't think you need anything other than that. And you don't need to know about histamine, I checked the specification and apparently you learn about it in unit 5!