Biology B3 Mark Scheme 21/05/12

I know you've done it once. But, i've changed it and this is what i think ill get

Could you quickly mark it and see what you think i got please. 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 13 marks= 32/45

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
1b) 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)-Lose 1
2ii) So that the Fusarium has better access to the nutrients in the solution and to keep them in suspesion (1) -Lose 1