AQA GCSE - Unit 3 (P3,B3,C3) New specification papers.

About the ventilation, is a positive pressure ventilator one that pumps air in, waits for air to go back out, then pumps in again?

AND is a negative pressure ventilator the "Iron Lung"??

Can somebody help me think of more points for the biogas generator evaluation below? I've only got one point for disadvantages of continous generators...

Evaluation continuous and batch biogas generators:

Advantages of continuous over batch
- more convenient (you don't have to keep emptying it, cleaning it, and refilling it)
- steadier rate of biogas production (it is continuously being produced, therefore it is more time-efficient)
- safer (less risk of accidents as it isn't emptied/cleaned/filled regularly)
- less labour costs (nobody needs to keep emptying/cleaning/filling it)

Disadvantages of continuous over batch
- generator is more expensive

In the specification, it asks specifically for an evaluation of the designs and production of gas. Not continual production or batches.

E.g.
disadvantages
- Co2 is released in the process
-The left over slurry is often toxic and hazardous to humans
advantage
- Good use of waste material
- Free (excluding biogas generator)
- More environmentally friendly
- Can be used in remote locations (eg. india)

E.g.
disadvantages of buried (beneath ground) generators
- Cooler beneath ground - won't get as hot which lessens the risk of enzymes denaturing
- Ground provides insulation to keep it warm in cold conditions

etc....

Would it be useful if i made a thread, exclusively for bio next week? this one is getting cluttered/overcrowded.

I think that would be a good idea. I think eventually it would be best if there be 3 separate threads for the 3 sciences as the exams approach us, in order to give us separate places for post-exam discussion/unofficial mark schemes etc.

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Positive pressure ventilators are usually hand held pumps, however they can be automated ones used in operation theatres when patients are in a critical state and their breathing needs to be regulated. The positive pressure device forces air into the lungs through the trachea and creates positive pressure inside the lungs (higher that outside) This higher pressure forces the air out until it is equal to outside (note: the inside of the lung never ensures negative pressure with this method as it never pulls more air out causing the inside of the lung to have a lower pressure than outside). More air is then forced in

Yes, the negative breathing aid is the Iron lung

Can someone please help explain some of B3 to me please, the particular topic being the structure of leaves and the stomata

Would it be useful if i made a thread, exclusively for bio next week? this one is getting cluttered/overcrowded.

Are there any for the other two as of yet?

Here are the official ones:

Biology

http://www.thestudentroom.co.uk/showthread.php?t=2291132

Chemistry

http://www.thestudentroom.co.uk/showthread.php?t=2291120

Physics

http://www.thestudentroom.co.uk/showthread.php?t=2342749&p=42502799#post42502799

too late bro, too late

I did this for unit2 as well, trust me I know what im doing, ive added 6 marker poll + links to past papers + revision and warn people about post exam discission. I also add an unofficial ms after the exam which i need to be OP to do. You have done none of this- New to TSR are you? Dw, leave it to me.

WOW, you're amazing! Me and my dinosaur ways and inexperience will just marvel at the amazement of your threads. Maybe improve your organisation as most people would have found that useful months before the exam, not one week away.

Feel free to differentiate between a long term REVISION thread and a pre/post exam discussion thread. All I'm saying is that I have experience doing this and have talked to section mods regarding post exam discussion etc.

That's wonderful. However, it is rude to create supposedly official exam discussion threads after a selection of others already have been created and then post on those threads the urls to your own unofficial exam discussions. I have no problem with other people creating discussions, just don't post them onto the original official threads because you weren't organised/bothered to create them earlier.