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AQA BIOL2 Biology Unit 2 Exam - 26th May 2011

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You need 1 of each type in the 2 daughter cells.

Label them like this

Type 1 version 1
Type 2 version 2

etc etc

You can get:

111
112
121
122
211
212
221
222

8 possibilities :smile:

You could write them all out but what if they game you a larger number like 50.

The correct answer is 2^(Number of chromosomes in haploid)

So for humans it will be 2^23

Reply 901

lolo-x

Original post by edebsi10

june 2010 can anyone tell me how they got 8 gametes for 'different types of gametes could be produced from this cell as a result of
different combinations of maternal and paternal chromosomes' cell has 6 chromosomes?????? :/

if you had A a B b C c, then there are 8 different ways they can be arranged, just by logic.
you can have:
ABC
ABc
AbC
Abc
aBC
aBc
abc
abC

Reply 902

mangerah

Do we need to remember the test for some things, like reducing sugars etc.?

Thanks

Reply 903

Twigleheight

Original post by Jorgeyy

I agree that 2 to the power of the number of chromosomes is easier btw I was just helping explain why ^^^^

Your explanation is good :biggrin:

I hope a question like that comes up, I'll be like yesss! haha

Reply 904

nasira372

Original post by kingsmod1

most of time its around 30 marks and u will get low A
its harder than it sounds because u lose marks for lots of various things lol

So basically Im screwed. I got 30/60 for my ISA

Reply 905

Mathematix

Original post by nasira372

You could write them all out but what if they game you a larger number like 50.

The correct answer is 2^(Number of chromosomes in haploid)

So for humans it will be 2^23

Yea I posted after that I understood that method but I was trying to explain WHY to the guy that it occurs like that :tongue:

Thanks though, would be very useful if I didn't know ^^

Reply 906

EffKayy

Urgh.. Good luck guys. Really cba sitting doing an exam for 1hrs 45!

Reply 907

Mathematix

Original post by nasira372

So basically Im screwed. I got 30/60 for my ISA

Try doing an EMPA which you don't find out results for until summer !!

Also, we only got 1 try because it's externally marked...

Reply 908

Twigleheight

Original post by edebsi10

thanks you made that soo simple basically 2 chromosomes in the previous question in each of the 3 cells two to tha power of three

Make sure you do 2^(however many chromosomes in the gamete) and you'll get the answer :smile:

You're welcome

Reply 909

EffKayy

Original post by Jorgeyy

Yea I posted after that I understood that method but I was trying to explain WHY to the guy that it occurs like that :tongue:

Thanks though, would be very useful if I didn't know ^^

Is it always 2^ no chromosomes? I haven't been taught that lol

Reply 910

Kaylaleigh

Original post by nasira372

Plant adaptations for water loss are stomata in pits to trap air. This reduces the water potential

This is what is says in my notes. Water potential of what though???

It decreases the concentration gradient for osmotic movement of water, the diference in water potential between the air trapped around the stomata and the in the stomata itself will be reduced

Reply 911

LauraMxx

Original post by Kandy_Kain_94

So basically you can afford to lose 20 marks and still get an A?

on one paper the mark out of 85 for an a was 54!

Reply 912

nasira372

Original post by Jorgeyy

Yea I posted after that I understood that method but I was trying to explain WHY to the guy that it occurs like that :tongue:

Thanks though, would be very useful if I didn't know ^^

Oh!!...Apologies

I just wanted to answer as its one of the very few things I know :colondollar:

Reply 913

cherri3

Original post by Unbiased Opinion

I know, and when people say the answers to things and you didn't get that. Sucks bad. :p:

Ouch.

I've got Ethics in the morning, I haven't revised it much at all, need to do some before I go to bed. Ah well it'll be done in 24 hours. :smile:

Yeahh but i'd want to know so i'd know what to expect at results... Thats even worse all essay writing good luck to you :smile:

I don't finish till friday i have chemistry but i am soo fed up of revision right now. :argh:

Reply 914

kingsmod1

if any1 needs help on bio 2, just pm on me and we can actually chat on skype
i wanna help all u noob biologists in unit 2 lol

just pm me if u want to leet me kno

Reply 915

iguess

For a question asking about gas exchange in insects...

•

Respirartory gases enter and exit through pores called spiracles

•

These are closed most of the time to prevent water loss

•

Spiracles lead to tracheae which are tubes where the gases travel along, and into even smaller ones called tracheoles

•

Numerous thacheoles mean bigger surface area

•

Short diffusion pathway for the gases to cells

•

Increases diffusion

•

Diffusion gradient occurs because respiring gases produce carbon dioxide and concentration of oxygen decreases as it becomes used up.

•

So oxygen diffuses along conc. gradient from atmosphere to tracheae, tracheoles and into cells. (and the opposite for carbon dioxide)

•

Ventilation occurs by mass movement of air when the insect's muscles contract, this makes the rate of diffusion faster.

Anything wrong or missing?
Please could anyone give the points for a question about tissue fluid? :smile:

Reply 916

Mathematix

Original post by EffKayy

Is it always 2^ no chromosomes? I haven't been taught that lol

2^ of pairs of chromosomes

As previously stated, humans is 2^23 not 2^46

The most that will come up will require 2^3 or something probs so you can systematically work it out since this isn't a maths exam..

The worst math you'll find is standard deviation or index of diversity

remember d = N(N-1) / sum of (sigma) n(n-1)

Reply 917

nasira372

Original post by Kaylaleigh

It decreases the concentration gradient for osmotic movement of water, the diference in water potential between the air trapped around the stomata and the in the stomata itself will be reduced

So the water cant move out because there is no gradient so transpiration is reduced. Think I understand now

Reply 918

Twigleheight

"The students plotted the distance moved by the air bubble against time on a graph. Describe how they could use the graph to calculate the mean rate of water uptake."

I have no idea o_O
Anybody know the answer? I don't know what paper the question came from so can't look up the answer scheme myself. We literally did nothing on potometers and they seem to come up on the majority of papers D:

Reply 919

Unbiased Opinion

Original post by cherri3

Yeahh but i'd want to know so i'd know what to expect at results... Thats even worse all essay writing good luck to you :smile:

I don't finish till friday i have chemistry but i am soo fed up of revision right now. :argh:

I know what you mean... I would hate to ever think I'd done well then not. That's never happened to me but that would be awful!

Haha, thanks. :smile: