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AQA BIOL2 Biology Unit 2 Exam - 26th May 2011

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Reply 800

ScienceGeek3

Original post by LifeIsGood

Page 185

Haha my bad, clearly haven't read the book thoroughly enough :tongue:

Reply 801

jessplease

Original post by ScienceGeek3

I was speaking to liviaaa about this earlier, she mentioned you need to know of the vessels leaving and entering the liver and kidneys too! I believe for the liver is the hepatic vein/artery and hepatic portal vein and for the kidneys it's the renal artery/vein.. I don't even think this is mentioned in the NT book!

yeahhhh you need to know entering and leaving heart, liver and kidneys. But before that it says names of the coronary arterys? and i haven't read about that anywhereee

Reply 802

xkate1019x

Can anyone explain antibiotic resistance to me please? so confused :/

hate chapter 13.

Original post by jessplease

yeahhhh you need to know entering and leaving heart, liver and kidneys. But before that it says names of the coronary arterys? and i haven't read about that anywhereee

what are the coronary arteries? D:

Reply 805

HaimishaParekh

6 marker on insects/fish? YES PLEASE.

Reply 806

ScienceGeek3

Original post by xkate1019x

Can anyone explain antibiotic resistance to me please? so confused :/

What don't you understand? Bacteria can be resistant to certain antibiotics due to random mutations or due the plasmid containing the resistant gene being passed on to them via conjugation from one species to another species - horizontal gene transmission or from one generation down to another generation vertical gene transmission. If the bacteria possess the resistance gene then it is no longer affected by that particular antibiotic, i.e. the antibiotic will not kill the bacteria. Therefore a "cocktail" of antibiotics are usually given in treatment in the hope that atleast one type of antibiotic will be effective. The bacteria can usually produce an enzyme e.g penicillinase (excuse the spelling) which can break down penicillin before the antibiotic can cause the bacteria any harm.

That's just from memory, some parts may be slightly off but I think those are the main points!

Reply 807

Master.K

Original post by DoaaK

hate chapter 13.

Everyone does! :rolleyes:

Original post by HaimishaParekh

6 marker on insects/fish? YES PLEASE.

What could they ask about insects? :confused:

Reply 808

jessplease

Original post by xkate1019x

Can anyone explain antibiotic resistance to me please? so confused :/

resistance occurs by chance due to mutation, and if you give antibiotics to someone who has a resistant bacterium, due to natural selection these bacteria will survive and then pass on this resistant gene by either horizontal or vertical gene transmission and therefore increase the frequency of resistant allele in population :smile:

Reply 809

parallal

Can someone please explain ventilation in insects please?

Reply 810

jessplease

Original post by DoaaK

what are the coronary arteries? D:

no idea!

Reply 811

Kandy_Kain_94

I think I'll be tackling the 6 mark question first

Reply 812

ScienceGeek3

Original post by parallal

Can someone please explain ventilation in insects please?

Movements in the muscles of the insects cause mass movements of air into/out of the trachea. Gas enters and leaves trachea through pores called spiracles. When spiracles open water can evaporate from the insect. For efficient diffusion, the diffusion pathway must be kept short, therefore limiting the size of insects.

Reply 813

Mathematix

Original post by Kandy_Kain_94

I think I'll be tackling the 6 mark question first

Same... unless its tissue fluid LOL

Reply 814

ChessMister

It's sickening to hear all these model answers

Reply 815

Nugard123

Original post by parallal

Can someone please explain ventilation in insects please?

Ventilation helps to cause mass movements of air in and out of the trachea. This is achieved by the contraction of muscles.

Reply 816

maymaymo

Original post by ksimmi25

Thank you

I think I kind of get it, better than I did before :biggrin:

but what would be the third replication? I know there would be 8 possibilities? - How do you work them out?

sorry it's not really clear.
So originally it's ii,
then this become Ii iI (during sc replication, the strands separate and become I, i, i and I which are joined by free nucleotides all 15N)
becoming : II, Ii, iI, II
this then becomes
II, II, II, Ii, iI, II, II II
8 results!

Sorry late reply, was revising som philosophy and ethics too :frown:

Reply 817

Kandy_Kain_94

Original post by Jorgeyy

Same... unless its tissue fluid LOL

I hope its tissue fluid lol...It's not about gas exchange in fish/insects :s-smilie:

Reply 818

Nugard123

Is this all we need to know about fish?

- The pharynx is lowered, and pressure decreases inside the fish's mouth, so water is drawn in.
- The pharynx then closes and pressure is high in the mouth, so water is forced out past the gills over the operculum.
- Gills have many filaments and lamallae to increase surface area for efficient gas exchange.
- The counter current system improves gas exchanges because blood travels in the opposite direction of water. This means that blood always has a lower oxygen concentration than the water, so the oxygen will diffuse into the blood.

Can anyone add to that or is that all we need to know?
Thanks :smile:

Reply 819

Mathematix