Biology · Oct / Nov 2022 · Paper 42 · Question 4

C6H12O6 ;

2C2H5OH + 2CO2 ;

any three from:

1

uses wastes (from farming / forestry) ;

2

idea that reduces use of, fossil fuels / oil / petrol / non- renewable fuel ;

3

less (pollution / damage to environment by) mining / drilling ; 4

to conserve, fossil fuels / non-renewables, for the future ; 5

idea that plants grown for biomass is an example of a sustainable resource ;

6

carbon neutral / no or small carbon footprint ;

7

does not contribute to, (enhanced) greenhouse effect / global warming ;

8

less (net) air pollution / no acid rain ;

9

AVP ;

disadvantages - any two from:

1

land could be used for food production ;

2

loss of habitats ;

3

loss of, species diversity / biodiversity / AW ;

4

loss of genetic diversity ;

5

uses land that could be used for, nature reserves / conservation ;

6

plants (grown in monocultures) are susceptible to, pests / disease ;

7

loss of soil nutrients / soil degradation / soil erosion / soil exhaustion / AW ;

8

need (high inputs of), herbicides / pesticides / water / fertiliser ;

any three from:

1

concentrations of xylose and ethanoic acid decrease, concentration of ethanol increases ;

2

steep / AW, decrease of, xylose and ethanoic acid until 62 hours ;

3

steepest change is between 6 to 12 hours ;

4

increase in ethanol concentration to 44 g dm–3 ;

5

small change in concentration(s), after / from, 62 hours ; 6

xylose reaches, 1 g dm–3 / almost zero, at 90 hours / at the end

or

ethanoic acid reaches 0.25 g dm–3, at 90 hours / at the end ;

one from:

(s)lower rate of increase of ethanol / less ethanol (in same time) ; take longer to reach same concentration of ethanol ;

line(s) / gradient(s) (on graph), less steep ;