Q1.
This question is about carbon.
The graph shows the mass of carbon added to and removed from the atmosphere each year.
 
(a)     Name process X.
___________________________________________________________________
(1)
(b)     (i)      Calculate the mass of carbon added to the atmosphere by respiration per year.
Answer = ____________________ billion tonnes
(1)
(ii)     Some scientists are concerned that the mass of carbon in the atmosphere is changing.
How does the data in the graph support this idea?
______________________________________________________________
______________________________________________________________
(1)
(Total 3 marks)
Q2.
Human activity affects ecosystems.
(a)     Draw one line from each human activity to the effect on ecosystems.
 
(2)
(b)     (i)      Deforestation also affects the atmosphere.
Give two reasons why deforestation takes place.
1. ____________________________________________________________
______________________________________________________________
2. ____________________________________________________________
______________________________________________________________
(2)
(ii)     Changes in the gases in our atmosphere can cause global warming.
Give two possible effects of a rise in the Earth’s temperature.
1. ____________________________________________________________
______________________________________________________________
2. ____________________________________________________________
______________________________________________________________
(2)
(Total 6 marks)
Q3.
Students investigated decomposition.
The students:
•        put some decaying grass cuttings into a vacuum flask
•        put a carbon dioxide sensor and a temperature sensor in the flask
•        attached the sensors to a data logger
•        closed the flask with cotton wool.
A vacuum flask was used to reduce the loss of thermal energy.
Figure 1 shows the investigation.
Figure 1
 
(a)     Give one advantage of using a temperature sensor attached to a data logger instead of a thermometer.
___________________________________________________________________
___________________________________________________________________
(1)
(b)     Figure 2 shows the results from the data logger for carbon dioxide concentration in the flask for the next 25 days.
Figure 2
 
(i)     Why did the concentration of carbon dioxide in the flask increase?
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(3)
(ii)     Suggest what has happened in the flask to cause the carbon dioxide concentration to level off after 20 days.
______________________________________________________________
______________________________________________________________
(1)
(Total 5 marks)
Q4.
Chickens are kept as farm animals to produce food. Free-range chickens are allowed to feed in a large space outside. The diagram shows how energy supplied in food to a free-range chicken is transferred.
 
(a)     Calculate the amount of energy “lost” in faeces.
___________________________________________________________________
___________________________________________________________________
Energy “lost” = ______________ kJ
(1)
(b)     Some farmers use the battery method. They keep large numbers of chickens in a small indoor space. The food yield from these chickens is higher than that from free-range chickens. Explain why, as fully as you can.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(4)
(Total 5 marks)
Q5.
The figures below show the levels of carbon dioxide in air from 150 000 years ago.
 
TIME	CARBON DIOXIDE CONCENTRATION	
1500 years ago	270 parts per million	
1800 AD	290 parts per million	
1957	315 parts per million	
1983	340 parts per million	
(a)     Explain why carbon dioxide levels in the atmosphere are changing.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(3)
(b)     It is suggested that the increased level of carbon dioxide in the air is causing the atmosphere to warm up (the “Greenhouse Effect”).
          Describe, as fully as you can, two major effects of global warming and how these may affect the human population.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(6)
(Total 9 marks)
Q6.
Compare the efficiency of these two food chains.
         Food chain A            grain → humans
         Food chain B            grain → bullocks → humans
          In your answer, make full use of the following data.
Food	Consumer	Percentage of available energy
transferred as useful energy	
Grain	Human	9%	
Grain	Bullock	12%	
Bullock	Human	10%	
          One kilogram of grain has 80 000 kJ of available energy.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
(Total 4 marks)
Q7.
 
          The graph shows the variations in the North Sea herring population between 1952 and 1974. These fish were formerly caught in large numbers by fleets of trawlers but fishing has been restricted since 1974 as a conservation measure. Herrings lay about 20 000 eggs per year but do not reproduce until they are about 3–5 years old, when they are about 25cm long. It takes 11 years for a herring to reach its mature adult length.
          The following  measures have been suggested to prevent overfishing:
•        limiting mesh size of nets,  
•        specifying maximum catch by each boat per year. 
•        prohibiting fishing in herring breeding grounds. 
•        prohibiting fishing at certain times of the year. 
          Evaluate their probable effects on both fish stocks and the fishermen, using the information given above.
(Total 9 marks)

Mark schemes
Q1.
(a)     photosynthesis
1
(b)     (i)      140
1
(ii)     (10 billion tonnes) more added (to atmosphere) than removed
allow ecf from part (b)(i)
1
[3]
Q2.
(a)      
extra lines from left cancels mark
2
(b)     (i)      any two from:
•        (to provide land) for farming / agriculture
•        (to provide land) for quarrying
•        (to provide land) for building
•        to provide wood for building materials
•        to provide fuel
•        to provide paper
2
(ii)     any two from:
•        changes in earth’s climate, ie droughts, flooding, hurricanes
ignore temperature rise
allow ice caps melt
•        rise in sea levels
•        reduce biodiversity
•        change in migration patterns
•        may change distribution of species
ignore acid rain and the ozone layer and forest fires
2
[6]
Q3.
(a)     any one from:
•        continuous readings
•        do not need to be there
allow automatic readings
•        (more likely to be) accurate
allow greater resolution
do not allow valid
•        reduces human error
allow easier to read
1
(b)     (i)      microorganisms
allow microbes / bacteria / fungi / decomposers for microorganisms, throughout
1
(microorganisms) respire
1
respiration / decay / microorganisms releases carbon dioxide
ignore carbon released
1
(ii)     all grass decomposed / decayed / rotted
allow idea that all microorganisms dead (due to accumulation of waste or lack of oxygen)
allow lack of / no oxygen (for respiration of microorganisms)
1
[5]
Q4.
(a)     115
1
(b)     any four from
less energy lost / used
as heat lost to the atmosphere
since warm indoors 
accept temperature controlled
(less energy lost) in movement
since movement restricted 
more growth / eggs
accept prevents loss of body mass or gets fatter / weight gain
4
[5]
Q5.
(a)     idea:
more (fossil) fuel burned (do not credit simply more people/cars/industry)
deforestation = less photosynthesis
deforestation = more respiration/burning
each for 1 mark
3
(b)     idea: 
climate change
for 1 mark
          warmer/colder/drier/wetter
food production affected/starvation
mayor ecosystems destroyed/damaged
any two for 1 mark each
6
          sea level rise
for 1 mark
          low land flooded
less food grown/starvation
homes/factories flooded
any two for 1 mark each
          Allow
polar ice caps melt
sea water expands
[9]
Q6.
(food chain) A gives 7200kJ
(of useful energy)
or 7.2MJ
or 7200000J
unit essential in each case
1
          (food chain) B gives 960kJ (of useful energy)
or 0.96MJ
or 960000J
unit essential in each case
credit 1 mark if both are numerically
correct but unit omitted
1
          same comparison made in each case
e.g. for each kilogram of grain
or refers to more stages in food chain
results in less efficiency
1
          (so) (food chain) A is 7.5 times more efficient than (food chain) B
or for every unit of useful energy given
to a person by B, A gives  units
or food chain B is only 13(.3)% as
efficient as food chain A
or makes a correct comparison
in percentage terms
1
[4]
Q7.
          ideas that:
large mesh
allows small fish to escape so they live long enough/grow big enough to breed
maintains stocks
          close season
maintains stocks
unless catch more in rest of time
especially important in breeding season
          closed areas
maintains stocks
especially important for breeding grounds
but can’t make fish stay inside area
          quotas
maintains stocks
plus difficulty of enforcement of any/all of above
any 7 for 1 mark each
          fisherman (effect of controls on)
reduced catches/less income  controls
harder to catch fish
but will ensure their future
any 3 for 1 mark each
to max. of 9
(credit other good but unanticipated reasons)
[9]