BIOL4 Biology Unit 4 Exam - 13th June 2011

Original post by SK-mar

i dont know which paper it is? if you type the q's out i will try my best to answer them for you...

Q6 Jun 8 BYA5

Here

Reply 82

Original post by arvin_infinity

Q6 Jun 8 BYA5

Here

well nitrogen fixation is where nitrogen gas is converted into ammonia for plants. im guessing they're assuming that ammonia = ammonium compounds which in theory it does. so it is viable.

also, for the other one - more movemement from organisms in 3rd trophic level as they have to chase they're prey/food. organisms in the 2nd trophic level eat plants which are non-moving organisms. so more movement = greater need to respire and to maintain muscle activity etc...

Reply 83

Original post by SK-mar

well nitrogen fixation is where nitrogen gas is converted into ammonia for plants. im guessing they're assuming that ammonia = ammonium compounds which in theory it does. so it is viable.

also, for the other one - more movemement from organisms in 3rd trophic level as they have to chase they're prey/food. organisms in the 2nd trophic level eat plants which are non-moving organisms. so more movement = greater need to respire and to maintain muscle activity etc...

Ammonium= NH4+
Ammonia= NH3 !!!!

Not sure how they are the same.

------
2nd one= Thankssss..got it :rolleyes:

Ive forgotten to ask 5 part (b) . I couldnt do it and not sure if its in the syllabus. I mean there must be a link between sickle cell and maleria.

Am sure uve got better things to which are more exciting than helping me out ..thanks again

(edited 12 years ago)

Reply 84

Original post by arvin_infinity

Ammonium= NH4+
Ammonia= NH3 !!!!

Not sure how they are the same.

------
2nd one= Thankssss..got it :rolleyes:

Ive forgotten to ask 5 part (b) . I couldnt do it and not sure if its in the syllabus. I mean there must be a link between sickle cell and maleria.

Am sure uve got better things to which are more exciting than helping me out ..thanks again

yeh i get what you mean about the ammonia and ammonium differences but maybe the mark scheme was just being generous?? to be honest i think the other answers are less fair as they are from other units and this isnt a synoptic paper. although they are a part of the old A level i guess...

any other questions u had, this is good revision for me also! :smile:

Reply 85

Original post by arvin_infinity

Ammonium= NH4+
Ammonia= NH3 !!!!

Not sure how they are the same.

------
2nd one= Thankssss..got it :rolleyes:

Ive forgotten to ask 5 part (b) . I couldnt do it and not sure if its in the syllabus. I mean there must be a link between sickle cell and maleria.

Am sure uve got better things to which are more exciting than helping me out ..thanks again

yeh i dont think its in the syllabus. but i would just say that R and U has the two highest frequencies of the allele for faulty haemoglobin. i dont actually know but im assuming that faulty haemoglobin cells may make you less susceptible to malaria, so people then survive and pass on this gene. so you say that there is a positive correlation between this and the data in the table.

(edited 12 years ago)

Reply 86

Original post by SK-mar

yeh i dont think its in the syllabus. but i would just say that R and U has the two highest frequencies of the allele for faulty haemoglobin. i dont actually know but im assuming that faulty haemoglobin cells may make you less susceptible to malaria, so people then survive and pass on this gene. so you say that there is a positive correlation between this and the data in the table.

Sounds right..

Didnt understand why they said heterozygote

There are other points can get away with but just out of interest.

Here is another one------ Jan 8 :

Answer to first question part a is so general ! didnt understand.

& Q2 (b) According to CGP energy from movement of H+ used to combine adp and pi

However mark scheme says something totally different which is based on movement of

excited electron. I thought energy of movement of exc. (e) along ETC is used to move

H+ then ..

Shed some light :rolleyes:

Reply 87

pieceofheaven

7

Original post by arvin_infinity

Ammonium= NH4+
Ammonia= NH3 !!!!

Not sure how they are the same.

------
2nd one= Thankssss..got it :rolleyes:

Ive forgotten to ask 5 part (b) . I couldnt do it and not sure if its in the syllabus. I mean there must be a link between sickle cell and maleria.

Am sure uve got better things to which are more exciting than helping me out ..thanks again

Sorry to butt in, but I think if you're heterozygous for the sickle cell allele, you get this 'sickle cell trait' phenotype, which gives you some resistance to malaria. http://en.wikipedia.org/wiki/Sickle_cell_trait
:smile:

I'm not sure why? Maybe it's harder for the parasite to survive in the slightly sickle-shaped red blood cells.

also: i think they just talked about the heterozygous genotype because they were assuming people who are homozygous and have sickle cell anaemia would have died too early to benefit from the malarial resistance :smile:

hope that helps! X

(edited 12 years ago)

Reply 88

Original post by arvin_infinity

Sounds right..

Didnt understand why they said heterozygote

There are other points can get away with but just out of interest.

Here is another one------ Jan 8 :

Answer to first question part a is so general ! didnt understand.

& Q2 (b) According to CGP energy from movement of H+ used to combine adp and pi

However mark scheme says something totally different which is based on movement of

excited electron. I thought energy of movement of exc. (e) along ETC is used to move

H+ then ..

Shed some light :rolleyes:

I agree 1a has a bit of a rubbish answer, but i think its just trying to get you to recognise that energy is lost between trophic levels and then to say that carnivores are usually at intermediate trophic level so level 3 an onwards kinda thing .... then they want you to explain how this energy is lost.

dont worry bout your photosynthesis answer because what you said is right. however what i've been told by my teacher is that we dont need to go into so much detail and the answer they give in the mark scheme is very basic but what we need to put down.

when electrons are carried through the transporter chain they are transported via carrier molecules, each one at a lower energy level than the previous one. energy is lost at these stages and this energy is used to combine adp and phosphate.

notice the point where i said 'energy is lost at this stage and this energy is used to combine adp and phosphate' ... it is here where all that H+ stuff happens but we dont need to write all that down for this question.....so they simplify it by saying what i wrote...

hope this helps...

Reply 89

Original post by pieceofheaven

Sorry to butt in, but I think if you're heterozygous for the sickle cell allele, you get this 'sickle cell trait' phenotype, which gives you some resistance to malaria. http://en.wikipedia.org/wiki/Sickle_cell_trait
:smile:

I'm not sure why? Maybe it's harder for the parasite to survive in the slightly sickle-shaped red blood cells.

also: i think they just talked about the heterozygous genotype because they were assuming people who are homozygous and have sickle cell anaemia would have died too early to benefit from the malarial resistance :smile:

hope that helps! X

ahh thanks, i guessed that it had that effect but surely we dont need to know this. however for this question it seems we do?? although as i said i reckon its cos its the old A-level spec so maybe its changed now...

Reply 90

INeedToRevise

8

January 2011 paper anyone?? Please??

Reply 91

pieceofheaven

7

Original post by SK-mar

ahh thanks, i guessed that it had that effect but surely we dont need to know this. however for this question it seems we do?? although as i said i reckon its cos its the old A-level spec so maybe its changed now...

I just checked, and it is in the medical diagnosis part of the unit 5 spec...kind of.

'Many human diseases result from mutated genes or from genes that are useful in one context but not in another, e.g. sickle cell anaemia.'

Which is so obscure it's ridiculous! :')

Reply 92

Original post by SK-mar

I agree 1a has a bit of a rubbish answer, but i think its just trying to get you to recognise that energy is lost between trophic levels and then to say that carnivores are usually at intermediate trophic level so level 3 an onwards kinda thing .... then they want you to explain how this energy is lost.

dont worry bout your photosynthesis answer because what you said is right. however what i've been told by my teacher is that we dont need to go into so much detail and the answer they give in the mark scheme is very basic but what we need to put down.

when electrons are carried through the transporter chain they are transported via carrier molecules, each one at a lower energy level than the previous one. energy is lost at these stages and this energy is used to combine adp and phosphate.

notice the point where i said 'energy is lost at this stage and this energy is used to combine adp and phosphate' ... it is here where all that H+ stuff happens but we dont need to write all that down for this question.....so they simplify it by saying what i wrote...

hope this helps...

SOmetimes they want very specific answer , but sometimes they want basic answer
which can be a pain

I would have never thought of explaining that..well now I know :wink:

---

For first one , carnivore can be secondary consumer and onwards ( I might be wrong :!)

----

Another question: Jan 08
7b last part ! Need someone to explain this to me :rolleyes:

Reply 93

Original post by arvin_infinity

SOmetimes they want very specific answer , but sometimes they want basic answer
which can be a pain

I would have never thought of explaining that..well now I know :wink:

---

For first one , carnivore can be secondary consumer and onwards ( I might be wrong :!)

----

Another question: Jan 08
7b last part ! Need someone to explain this to me :rolleyes:

yep sorry thats wat i meant. plants level 1, primary level 2, carnivores level 3 and onwards sorry should have made this more clear.

and ill take a look at that question for you...

Reply 94

Original post by arvin_infinity

SOmetimes they want very specific answer , but sometimes they want basic answer
which can be a pain

I would have never thought of explaining that..well now I know :wink:

---

For first one , carnivore can be secondary consumer and onwards ( I might be wrong :!)

----

Another question: Jan 08
7b last part ! Need someone to explain this to me :rolleyes:

dont worry bout the last part its to do with chi-squared and that wont come up in the exam as its only needed for the EMPA.

I ready through the first part though and it looked quite hard actually. i actually don't know the difference between the gamete genotype and the offspring genotype? ... maybe im being silly i dont know could someone explain.

again, we might no longer need to know this as its old spec but hey!

Reply 95

Abby :)

8

Woooo 2 weeks to go! Fun. Not. =[

Reply 96

Original post by SK-mar

dont worry bout the last part its to do with chi-squared and that wont come up in the exam as its only needed for the EMPA.

I ready through the first part though and it looked quite hard actually. i actually don't know the difference between the gamete genotype and the offspring genotype? ... maybe im being silly i dont know could someone explain.

again, we might no longer need to know this as its old spec but hey!

I remember my teacher said that can come up in the exam. Check with someone else

yes they are different nd you do need to know this:

So once you found gamete genotype you cross those and find the offspring
Basically gametes are cell produced by meiosis whereas offspring developed zygote(sperm+egg)

In this question : Agouti White
These are gametes (B+b)(A+a) (b+b)(a+a) Another way of writing it : BA-Ba-bA-ba ba-ba-ba-ba ( well you dont want to repeat it 4 times)

hope it helps..

Reply 97