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BIOL4 Biology Unit 4 Exam - 13th June 2011

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Reply 1620
Original post by maths3
For the equation I wrote;

ADP + Pi --> ATP + H20

Will I lose a mark for the H20?


I see what you mean but i really don't think thats part of the equation so i think you may drop the mark. only because if you look at it in a chemistry frame of mind - the equation simply does not work as there are no hydrogens or oxygens on the reactants side. plus for the formation of ATP in general, from ADP + Pi, H2O is not a product.
Reply 1621
Original post by SK-mar
I see what you mean but i really don't think thats part of the equation so i think you may drop the mark. only because if you look at it in a chemistry frame of mind - the equation simply does not work as there are no hydrogens or oxygens on the reactants side. plus for the formation of ATP in general, from ADP + Pi, H2O is not a product.


Yes it is. I know my equation is correct but AQA is so specific that I'm unsure if it would make a difference.
Reply 1622
Original post by maths3
Yes it is. I know my equation is correct but AQA is so specific that I'm unsure if it would make a difference.


it is if you include oxygen as a terminal electron acceptor, and hydrogen ions in the equation. but all it wanted was the formation of ATP from ADP + Pi....
Reply 1623
Original post by SK-mar
it is if you include oxygen as a terminal electron acceptor, and hydrogen ions in the equation. but all it wanted was the formation of ATP from ADP + Pi....


You're talking about respiration, I'm talking about just ATP which can be hydrolysed (split up by water) to form ADP + Pi. It's a reversible reaction and the reverse of hydrolysis is condensation (the elimination of a water molecule from two molecules to form one larger molecule).

Here is a link

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/ATP.html
hey does anyone know if ecotherms use homeostasis in body temperature im confused cus homeostais is the maintenance of a constant internal environment, isnt it just that ectotherms achiev this in a different way, they can still achive homeostasis? jus they achiev it by theri environment? hence bothe ectotherms and endotherms maintain body temperature by homeostasis? im reallyt confussed??!!
Has anyone posted the paper yet??
Reply 1626
Original post by coffee345
thats exactly what i wrote!
except from the fact that i added methane can be burnt and used to heat houses to rear domestic livestock? o.o


ooh so you think I could get a mark for the fuel one or is it a bit too brief? ermm...the next question, do you think i've just got 1 mark out of the 2 since I didn't mention enzymes but came across the point that the anaerobic bacteria would stop functioning with the increased heat?
I think in total i've dropped around 13 marks, would that be enough for an A* cos I think i've done some draft mistakes :frown:
Reply 1627
Original post by samzurai
if you get 70% in these papers your more or less guaranteed an A


What do you think an A* could be? :wink:
Reply 1628
Original post by SK-mar
but it said that it was significant in the question?


I said for the second mark something like we are 95% confident that the data is significant. Didn't mention anything on null hypothesis tho:/ also mentioned that there is a less than 5% probability that chance has influenced the data.
Reply 1629
Original post by somaliya
I said for the second mark something like we are 95% confident that the data is significant. Didn't mention anything on null hypothesis tho:/ also mentioned that there is a less than 5% probability that chance has influenced the data.


yeh your second point is right. i also said that but in a different way: There is a probability of 5% or less that the results are due to chance. but then i also mentioned about the null hypothesis as i couldnt think of what else to put? .... althoughhhhh.....

normally in the mark schemes they give 1 mark for getting the right idea about how the 5% should be used and 1 mark for using the words probability and chance in the right way. so simply saying: there is a probability of 5% or less that the results are due to chance... should be enough for both marks.

as is what you said but did you use the word probability in yours????



edit: if you look at question 7e from jan 2010 paper: the markscheme awards marks for:
- using the words probability and chance in the right way according to the data
- mentioning whether the null hypothesis is accepted or rejected
- determining whether the results are significant or not...

so we both should be ok :smile:
(edited 12 years ago)
Original post by MessyRoom
To all people worried about this exam after looking on TSR;

The users of TSR are not representative of the country's students sitting this exam. By being active members of a student website and posting in threads such as this proves you have a higher than average interest in your schooling, education and exams.

Most people in TSR are going to be C grade candidates or above - count yourself as one of them and relax :smile:


Thanks mate!
Original post by SK-mar
I said yes if you breed with parents of genotypes 'bb' and 'bb' or parents of genotypes 'bb' and 'bbi' .... if this is the case then there is 100% chance of offspring being chocolate fur. and because 'b' is dominant to 'bi' .... so for any heterozygous 'bbi' formed it is still chocolate.


You're right for the first one, but the question asked if it was possible to breed an entire population of chocolate coloured cats. So if the parents were bb and bbi they could produce offspring that were bbi and they would carry the cinnamon genotype. If they bred with another bbi then you would have a 25% chance of cinnamon cats - therefore they must be 'bb' and 'bb' for the population to be chocolate. :smile:
Reply 1632
Original post by gorillaz121
You're right for the first one, but the question asked if it was possible to breed an entire population of chocolate coloured cats. So if the parents were bb and bbi they could produce offspring that were bbi and they would carry the cinnamon genotype. If they bred with another bbi then you would have a 25% chance of cinnamon cats - therefore they must be 'bb' and 'bb' for the population to be chocolate. :smile:


yeh but a population can be just one generation of cats, the question did not specify over how many generations the population needs to be formed.

population = all the organisms of one species in a habitat .... so it would be viable.

and it never used the word 'entire' in the question, that is over-exagerating the population thing there. lol.
Reply 1633
Original post by coffee345
1.Calculation
- 4% this is what i got as well
2.What does hardy about the frequency over 10 generations
- that the frequency of the alleles in the population won't change i wrote that the proportion of recessive alles will remain the same from generation to generation provided that there were no mutations, selection, they're isolated etc.
3. Use probability and chance
- there is a probability of 5% or less that the change in allele frequency is due to chance. therefore we reject our null hypothesis that the frequency of alleles wont change. (not sure about this, can someone back me up if they put something similar,cheers) there was no difference at 0.05 probabilty and the results was due to chance
4. What type of selection is this
- Stabilising selection
- The recessive allele has decreased in frequency. it was at the extreme of the range of alleles as the hardy calculation proved it was only present in 4% of the population. with a further decrease it means that alleles closer to the middle of the range are being selected for, hence its stabilising.
i wrote directional as i explained before...:smile:


Mites Question (cant remember many of these question so i'll try my best.)

1.Why was the data selected at random
- to remove bias from the experiment. It allows us to form a valid correlation between numbers of mites and successful breeding chicks. (not sure about 2nd point) i wrote to eliminate bias and to allows a stats test to be calculated and performed
2.Describe the data and does it agree with the statement that more mites decrease successful breeds???? (think that was the question)
- with small increases in mites the amount of successful breeds fluctuated at around 80.
- with a large increase in mites (170), the number of successful breeds decreases to 42 from 86 at 15 mites.
- However, without further data we cannont conclude that an increase in mites does cause a decrease in successful chicks.
i wrote basically the same and i included about that results might be due to another factor
3. State a null hypothesis
- there is no significant statistical difference between the numbers of mites present and the amount of successful chicks. exactly what i wrote
4. Spearmans showed a negative correlation between mites and successful chicks what does this mean?
- That an increase in mites does not effect the number of succesful chicks. (is this right?) ... i wrote a negative correlation "/
5. Describe the data in the graph
- For tits with large oil glands, many of the points are close or touching the line of best fit. However, for tits with small oil glands, few points are close to the line or touching it. However, overall there is a slight positive correlation. i cant rememver this one >.<
6. Does measuring oil gland size increase reliability?
- yes because different tits have different sizes of oil glands and therefore we are removing this variable from the experiment. (dunno if this is right) .... i wrte about surface area as i explained before
7. Mites eat pathogenic bacteria and fungus, how could this effect tits and their breeding?
- tits are less likely to contract pathogenic disease or fungus infection so less energy is used to fight them off and more energy can be used for reproduction and breeding behaviour. therefore the numbers of successful breeds are likely to increase.
i outlined reproductive success and about survival...not sure though >.<


I am a bit confused. The data given in the table more or less told us that increased mites decrease sucessful breeds, but in the question to what effect did the mites have on breeding, you said mites increase successful breeds?
Original post by fairytonia
as i rember it thhe questions asked you to tick or leve blank


I highly doubt i will lose marks for putting a cross instead of leaving it blank. If the answer is correct, it's correct
Original post by Rainbow249
Thanks mate!


Thanks for the vote of confidence but I want an A not a C! :P
Ahhh, right. Well i wasn't too sure so I said no, but then said though it was possible due to reproduction and selection of gametes being random and that, but that it was a very low chance of occurence :s-smilie: I hope I get an A! D:
Original post by joyciejones23
Thanks for the vote of confidence but I want an A not a C! :P


I REALLY REALLY want an A but really not sure! Fingers crossed for low grade boundaries!
Grade boundary prediction guys?
Oh fiddlesticks, it would seem that I assumed far too much with regard to the question asking about net productivity differences in March and August.

Specifically, I rejected respiration differences alone because I, for some reason, decided to think that I should deduct all ‘waste’ from the Gross. As a result, I suggested that more desirable biomass would be produced in August whereas March would focus on growth of the plant as a whole rather than the crop. This makes no sense as you wouldn’t use crop production as a metric in March, months before any crop arises. >_<

Meh, I waffled excessively on quite a few questions so barely had enough time to go back and check most of my answers (or even do most of the Tit question >_<). I shall simply cross my fingers and hope. Good luck all, though I’m sure you won’t need it. I expect your self-deprecation and anxiety is blinding you to your true abilities and performance. :smile:

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