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Biology B3 Mark Scheme 21/05/12

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For the salt one

It said, water is a substance in the blood.

Name Two other substances found in the urine

1) Urine
2) Salt

Salt is a substance and it's found in the urine surely those two are right?

don't you mean urea?

Reply 121

Welbeck

Original post by Fordey

I put urea and water as two substances in urine

They already mentioned water so you will get 1 mark

Reply 122

michelfish

Original post by Aarongreatbanks

But it said substances? Mineral ions isn't a substance, it's a group of them

Salt is a substance found in the urine is it not?

How did you think i did

belive me. if it did say substance they would accept mineral ions more than salt as this was a biology paper (they aren't quite chemists :smile:

lol) but if i was going to be picky i would not accept salt as it would be in a solution (urine) so the ions would dissacociate as salt is soluble in water which is also present in urine. :smile:

Reply 123

Aarongreatbanks

Original post by PoorLoser

don't you mean urea?

Yeah :L

but salt would be right?

And for the why doesn't the farmer use fish fat, i put because it's too expensive, is that right?

Reply 124

Aarongreatbanks

Original post by michelfish

belive me. if it did say substance they would accept mineral ions more than salt as this was a biology paper (they aren't quite chemists :smile:

lol) but if i was going to be picky i would not accept salt as it would be in a solution (urine) so the ions would dissacociate as salt is soluble in water which is also present in urine. :smile:

i was going to put mineral ions but it thought that its self isn't a substance

Reply 125

MikeyP96

what do you think the grade boundaries will be?

my predictions are:
33+ A*
26 A
23 B
18 C

I think it was a little harder than the past papers and i cant imagine them booting the grade boundaries to 38+ for A*. I think I lost between 6-8 marks at the most 10.

Reply 126

mimosa123

I think I did ok hope i got a* however I think(judging from past papers) that this will be around 33 or maybe 32 for an A*. A past paper was WAYY easier than this and you needed like a 32 for an A*. I really like this mark scheme. thanx

i think I got around 36. Remember if your answer is not in this mark scheme in the official one it has 'Accept' answers so it is not only one answer to a question except for maths questions.

Who is doing Chemistry Unit 3 on thursday.

I heard B2 was hard even though i didnt do it.

Reply 127

flyhigh99

Original post by g.k.galloway

I need 97 ums in bio 3
60 in chem 3
and 70 ish in phys.

I guess physics and chemistry is easier for all of us,

You know when we get the results, are we going to get the results for this test (b3)
or are they going to give just the overall of our biology exam, (and not tell us what we got in this unit?)

Reply 128

kashagupta

Original post by MikeyP96

My predictions are exactly the same and yeah I think I've lost about 8-10 marks too! What do you need for your target grade?

Reply 129

kashagupta

I'm doing c3 on Thursday too :smile:

feeling prepared?

Reply 130

mimosa123

For the urine i put
Urea
excess mineral ions eg Salt

I am very specific because in the past i have lost marks for not being specific.

OMG i noticed after i finished my exam that the invigilator stopped us 3 minutes earlier. And they wouldnt stop gossiping. They were like mice. Do you think that fair??

Reply 131

michelfish

Original post by Aarongreatbanks

i was going to put mineral ions but it thought that its self isn't a substance

don't worry i completely get what you are saying

i'm just trying to say the biology mark schemes a bad at the best of times (you are right but you could but 100 things that are right (uric acid etc.) but you won't get marks because it wont be on the mark scheme. :smile:

Reply 132

Dominic101

People always say that the exams were harder that the past papers but considering on this thread most people got like 38/45 the boundaries will deffo be high. Everyone who came out of the exam in my school said it was easy

Reply 133

Aarongreatbanks

Right here is what i put please be as critical as possible so i get a fair view of what i get. What do you think? i will put the marks available in brackets

1a) i) The heart rate rises rapidly six times (to a high value) in the thirty minute period meaning they run six times (1)
ii) 2.5 minutes (1)
b) The increaed heart rate increases the blood flow which means that there is more oxygen and glucose delivered to the muscles which is used for respiration. This increaes the rate of respiration so more energy is released and avaialble to the muscles and they use it to contract. The blood flow allow removes co2 and lactic acid, and limits anaerobic respiation (4)
2 a) The nitrogen is used by the microogranisms for growth, the lid prevents microogransism contaminating the culture and oxygen is removed because fermentation needed anaerobic conidtions(2)
ii) Carbon dioxide (1)
b) 0.62 (2)
ii) Adding fish fat, increases the proportion of methane in the biogas. Also adding the fish fat increases the yield of biogas and methane. Increasing the amount of fish fat increases the yield of biogas and methane (3)
c) It would be too expensive(1)
3 a) Aerobic respiration(2)
ii) So that the Fusarium has better access to the nutrients in the solution and to keep them in suspesion (1)
b) The fusarium would get caught and stuck on the paddles(1)
c) Chicken has more protein(1)
ii) Less fat and less cholesterol(2)
4a)The is a higher concentration of these mineral ions in the roots than in the soil so the mineral ions would need to be moved against a concentration gradient and diffusion is along a concentration gradient from a area of high concentration to a area of low conentration (3)
ii) Active transport(1)
b) i) The root hair cells increase the surface area of the roots(1)
ii) Mitochondria is where repsiration takes place and where energy is released. By having more mitochondria, it means that more respiration takes place and more energy is released that can be used for active transport (2)
iii) The Starch is a carbohyrate store that can be broken down to glucose and to use for repsiration to release energy for active transport (1)
5 a) Urea, salt (2)
b) The glucose is filtered out of the blood in the kidneys. The glucose then goes into the kidney tubule and all of it is reabsorbed by active transport so that none is left in the kindey tubule (3)
c) There is too much glucose to be reabsorbed so not all of it is reabsorbed and the isn't enough energy avialable for all of the active tranpsort required (2)

6a) The DAS reduces the amount of fermentation because increasing the DAS concentration, decreases the percentage of alcohol produces. Also, increasing the DAS reduces the percentage of maltose used. When there is no DAS all of the maltose, glucose and fructose is used. When there is DAS, the percentage of maltose used declines but the amount of glucose and fructose isn't affected (3)
b) The Maltose molecure is too large so can't fit through the cell membrane (1)
c) The enzyme digests maltose into two molecules of glucose which can be absorbed by the yeast as it is small enough, but when DAS is present, no enzyme is released so the maltose isn't broken down and the maltose molecule is too large and can't be absorbed by the yeast. (2)
d) 1.DAS reduces the percentage of alcohol produced (1)
2. DAS means that most of the malt extract is not used, so materials are wasted or more has to be (1) used

I think i dropped 11 marks= 34/45 :'( no A* for me

I think i dropped marks here:

1a) i) The heart rate rises rapidly six times (to a high value) in the thirty minute period meaning they run six times (1)- Lose 1 mark
2 a) The nitrogen is used by the microogranisms for growth, the lid prevents microogransism contaminating the culture and oxygen is removed because fermentation needed anaerobic conidtions(2)- Lose 2 marks
5 c) There is too much glucose to be reabsorbed so not all of it is reabsorbed and the isn't enough energy avialable for all of the active tranpsort required (2)- Lose 2 marks
6a) The DAS reduces the amount of fermentation because increasing the DAS concentration, decreases the percentage of alcohol produces. Also, increasing the DAS reduces the percentage of maltose used. When there is no DAS all of the maltose, glucose and fructose is used. When there is DAS, the percentage of maltose used declines but the amount of glucose and fructose isn't affected (3)- Lose 3 marks
6 c) The enzyme digests maltose into two molecules of glucose which can be absorbed by the yeast as it is small enough, but when DAS is present, no enzyme is released so the maltose isn't broken down and the maltose molecule is too large and can't be absorbed by the yeast. (2)-Lose 1
5 a) Urea, salt (2)-Lose 1
2c) It would be too expensive(1)-Lose 1

(edited 11 years ago)

Reply 134

Zigggyy.

Original post by mimosa123

Hey sorry!

Just a wee bit paranoid so wondered if you thought these were okay:

Saying 'ion' instead of 'mineral ions'
Saying starch/glucose is stored in the root cells as food for the plant?

:') thanks!

Reply 135

Tazz56

Original post by metaltron

I'd say 41. 1 mark lost on 2a) and 5b). No marks 5 c).

for 6 b) / c) can you mention that yeast can only break down simple sugars ? and the enzyme is used to break down the maltose into simple sugars so that they can be used by the yeast for etc.... ?