Today's AQA Biology A Unit 5

Yes. How did people find it today?

I thought mine went well. My revision over the last couple of days has been invaluable. Getting into school at seven to do some last-minute revision (quite literally) helped as well.

Today's paper seems to be the easiest one set so far. Anyone agree?

J.

Reply 1

SAM*

Yeah it was OK, like you i've mastered the art of last min prep! the paper was no where near as challenging as i thought it would be, their was nothing on photosynthesis or the really complicated parts of genetics! but the rhizobium question got me really worked up?

Reply 2

madmazda86

Last night, a month after we did genetics, the whole homologous chromosome pair thing finally clicked! :wink:

So dratted typical though - I spent ages last night revising Hardy-Weinberg and Chi-squared, and what do I get? The flippin' biodiversity index for seaweed - gah.

That question on the cow's energy uptake was plain weird - more maths maths than biology maths if that makes sense. There was hardly anything on photosynthesis either - but it was a nice paper, and I think I did okay in it :smile:

And we start coursework tomorrow - whoopee, not!

Reply 3

hornblower

madmazda86

Last night, a month after we did genetics, the whole homologous chromosome pair thing finally clicked! :wink:

It finally clicked for me last night as well - I never understood it properly at GCSE! I finally understood the nitrogen cycle yesterday as well!

madmazda86

So dratted typical though - I spent ages last night revising Hardy-Weinberg and Chi-squared, and what do I get? The flippin' biodiversity index for seaweed - gah.

Happen's to all of us - Sod's Law!

madmazda86

That question on the cow's energy uptake was plain weird - more maths maths than biology maths if that makes sense. There was hardly anything on photosynthesis either - but it was a nice paper, and I think I did okay in it :smile:

And we start coursework tomorrow - whoopee, not!

The cow question has come up before. It had me stumped for a while. Everyone managed to get different answers for that one!

I start a second piece of A2 coursework next week for some reason.

J.

Reply 4

madmazda86

Yeuch - we started ours today. I thought our teacher was taking the mick at first, but no alas :frown:

More stats - yay!

Reply 5

Electric Magic

I pretty much did my revision two days before, and I went in hoping I wouldn't make an idiot of myself (ie nothing less than a C) but I think I had a good chance of getting an A. I still blew it though - the fire alarm went off during the exam and it messed up my concentration. I can't be bothered to explain the full story here but I missed out on about 5 really easy marks because I ran out of time.

Anyway, I revised Hardy-Weinberg too, and memorised all 5 equations. :frown:

Reply 6

hornblower

Electric Magic

Oh well!

Go on, tell us about the fire alarm!

J.

Reply 7

happydadtoo

madmazda86

Yeuch - we started ours today. I thought our teacher was taking the mick at first, but no alas :frown:

More stats - yay!

As you are only allowed to submit COMPLETE investigations for A2, it seems your teacher is prepared to double his/her marking load in order to give you some hope of raising your A2 coursework marks. They would only inflict this on themselves if a) they were masochists or b) you had not done well....
Be grateful and ensure you do it well. The stats bit is easy enough - there are enough stats sites on the web that all you have to do is submit data as an Excel spreadsheet and collect the answer...
Just make sure you collect enough data (usually 30 numbers, from at least 5 categories and 3 replicates - work as a team and pool class data) and in a form that allows easy stats - chi-squared is the easiest, so get categorical data and ensure you have a clearly thought out null hypothesis.
Prelim expt is easy too - just don't do enough to be meaningful, then use full expt (whole class) to correct this 'error'. You do the stats (line by line) on prelim expt, then use class calculation for final expt (your techer can even do the stats for that bit and give them to you as they are the same for the whole class) :wink:

Reply 8

madmazda86

happydadtoo

Oh, I'm fine with the stats! I did standard deviation etc at GCSE and this is exactly the same :biggrin:

I love stats because you just have to learn the methods, there's no facts required :wink:

I'm doing the rate of respiration in yeast experiment but my head was so stuffed up with cold when I did the plan that I doubt I'll get high marks for that section. I'm hoping to make up for it in my analysis and evaluation sections as I'm usually better at those.

Why is it more beneficial to use the pooled data than my prelim data? I know it's a bigger sample and everything, but I calculated the standard deviation of my prelim results and compared it with the standard deviation of the class results. My prelim results had a lower s.d so I decided to use them - as they are a smaller sample, in order to ascertain how close my mean results are to the mean of the true population of yeast cells I calculated the standard error of each result. My glucose and sucrose measurements were within the +/-1.96 SE confidence limit but lactose wasn't, thus I'll have to put in my evaluation that the lactose measurements were not a true representation of the respiration rate for a whole yeast population for that substrate. Because I calculated standard error etc, would that mean it's okay to use prelim data rather than class data?

I decided to use a paired t-test rather than Mann-Whitney because my prelim data only has three categories and M-W requires more. I know that neither test is really that suitable but those were the ones we had to choose from and it gets me the marks so I won't object :wink:

I think they decided to give us the coursework now so we won't be fretting over it in the latter half of the term - except alas my Chemistry teachers had the same idea so now I'm lumbered with two lots of analysis/evaluation to finish this week :frown:

Reply 9

pinkfairy

why do people assume the OCR board is easy for biology?