Mark Scheme for Biology unit 3 21/05/2012 all questions answered

Showing 1 to 7 of 7

1a) i) There are six ‘peaks’ between 7.5 and 18 minutes. (1)
ii) 2.5 minutes (1)
b) Supply oxygen (1), glucose (1), remove carbon dioxide (1) , lactic acid (1), to limit anaerobic respiration (1), to create energy for exercise (1). (Max 4)
2 a) To keep out oxygen (1) which would result in aerobic respiration, whereas biogas is produced best in anaerobic conditions (1).
ii) Carbon dioxide (1)
b) 0.62 (2)
ii) Adding fish fat, increases yield of biogas/methane (1). Better quality biogas, as higher proportion of methane (1).
c) It would be too expensive to buy the fish fat as he can’t fish himself 100km from the coast. Therefore, better quality biogas not an economic advantage (1).
3 a) Aerobic (1) respiration (1)
ii) So that all Fusarium has equal access to the minerals, resulting in even growth (1). Even control of temperature around the fermentor (1). (Max 1)
b) Would get tangled around paddles (1).
c) Chicken has more protein for making new muscle cells (1).
ii) Less fat/cholesterol, so less risk of circulatory problems (1). More dietary fibre, reduces risk of colon cancer (1).
4a) Higher concentration in plant roots than in soil, so absorption against the concentration gradient (1). Diffusion is along the concentration gradient (1).
ii) Active transport (1).
b) i) Larger surface area (1)
ii) Mitochondria site of respiration in a cell (1), so more mitochondria results in more respiration, increasing rate of active transport (1).
iii) Starch broken down to glucose when needed for respiration (1).
5 a) Urea, mineral ions (2)
b) All reabsorbed (1), first by diffusion (1), and the by active transport (1)
c) Kidney wants to reduce glucose levels so that they are healthy (1), so selective reabsorption means than not all glucose is reabsorbed (1).

6a) Increasing DAS concentration, decreases yield of alcohol (1), numerical evidence (1). DAS only results in less maltose being used (1), glucose and sucrose not affected (1).
b) Maltose too large, so insoluble (1)
c) Enzyme is a carbohydrase (1) which digests maltose into two molecules of glucose which can be used for respiration (1). DAS stops production of enzyme so maltose cannot be digested and used for respiration (1).
d) DAS reduces yield of alcohol, reducing profit (1). DAS means that most of the malt extract is not used, so killing DAS means manufacturer has to spend less on malt extract (1).

Modified once, last modified by Sarah Richard on Mon 21st May, 2012 @ 17:21

Posted: 21-05-12 17:20 by Sarah Richard

wooooo! :D that looks... pretty positive! :D

Posted: 21-05-12 17:24 by Neon

Yep. From the student room. It's really good. I got all the maths questions correct, 2.5 and 0.62 I got correct and the 2 waste products. By the way Cedonia what did you write for the urine concentration question on hot and cold days

????

Posted: 21-05-12 17:34 by Sarah Richard

has anyone got any clue what the grade boundaries would be???

Posted: 21-05-12 18:09 by Muzz :P

isn't that cheating , unless all people have done it 

Posted: 21-05-12 18:11 by Connah Greenhalgh - Team GR

Hence why I only put it on here and everyone should have done it

Posted: 21-05-12 18:40 by Sarah Richard

ok

Posted: 21-05-12 18:43 by Connah Greenhalgh - Team GR