Nutrient Cycles Revision pack
Revision Pack
Nutrient Cycles
Past Paper Questions
Name:
Q1.
The mesquite tree grows in dry areas which have soils with low concentrations of ions.
Its roots grow down to 25 metres and contain nitrogen-fixing bacteria. It is considered a pest in
areas where farm animals graze because it out-competes grass. In some areas, young
mesquite trees are cut down and then ploughed into the ground. This is expensive but makes
the soil slightly more fertile for a few years.
(a) Using the information given, explain one way in which mesquite trees are adapted for
survival.
______________________________________________________________
______________________________________________________________
(1)
S (b) Name the type of competition occurring between mesquite and grass.
______________________________________________________________
(1)
,Nutrient Cycles Revision pack
S (c) Explain how ploughing the mesquite into the soil makes it more fertile.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(3)
(Total 5 marks)
Q2.
The diagram shows a river system in an area of farmland. The numbers show the nitrate
concentration in parts per million (ppm) in water samples taken at various locations along the
river. Concentrations above 250 ppm encourage eutrophication in the river.
(i) Explain how farming practices might be responsible for the change in nitrate concentration
in the water between point X and point Y.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(ii) Describe the effect the nitrate concentration may have in the river at point Y.
___________________________________________________________________
___________________________________________________________________
,Nutrient Cycles Revision pack
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(5)
(Total 7 marks)
Q3.
In autumn when there is no crop, farm land may be used to grow mustard. The mustard absorbs
nitrates which otherwise can leach out of the soil at this time of the year. The mustard is
ploughed back into the soil just before sowing of the main crop in the spring.
(a) Nitrogen compounds in the mustard plants are made available for the main crop after
ploughing in spring. Describe the role of microorganisms in this process.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(5)
(b) Explain why it is important for the farmer to reduce the leaching of nitrates.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
, Nutrient Cycles Revision pack
(2)
S (c) Plants absorb a number of other nutrients from the soil including phosphates.
Describe why phosphates are needed by a growing plant.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(4)
(Total 11 marks)
Q4.
(a) Farmers who grow wheat sometimes leave a field fallow for a year by not growing a crop
in it. The concentration of nitrate ions in the soil decreases when a field is left fallow.
(i) When grass is grown in the field, fewer nitrate ions are lost than when the field is left with
bare soil. Explain why.
______________________________________________________________
______________________________________________________________
(1)
(ii) A crop of leguminous plants such as clover may be grown in the field and then ploughed
in. Explain why less fertiliser would be needed for the wheat crop in the following year.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(b) The table gives information about the yield and profitability of a wheat crop grown using
different amounts of fertiliser.
Revision Pack
Nutrient Cycles
Past Paper Questions
Name:
Q1.
The mesquite tree grows in dry areas which have soils with low concentrations of ions.
Its roots grow down to 25 metres and contain nitrogen-fixing bacteria. It is considered a pest in
areas where farm animals graze because it out-competes grass. In some areas, young
mesquite trees are cut down and then ploughed into the ground. This is expensive but makes
the soil slightly more fertile for a few years.
(a) Using the information given, explain one way in which mesquite trees are adapted for
survival.
______________________________________________________________
______________________________________________________________
(1)
S (b) Name the type of competition occurring between mesquite and grass.
______________________________________________________________
(1)
,Nutrient Cycles Revision pack
S (c) Explain how ploughing the mesquite into the soil makes it more fertile.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(3)
(Total 5 marks)
Q2.
The diagram shows a river system in an area of farmland. The numbers show the nitrate
concentration in parts per million (ppm) in water samples taken at various locations along the
river. Concentrations above 250 ppm encourage eutrophication in the river.
(i) Explain how farming practices might be responsible for the change in nitrate concentration
in the water between point X and point Y.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(2)
(ii) Describe the effect the nitrate concentration may have in the river at point Y.
___________________________________________________________________
___________________________________________________________________
,Nutrient Cycles Revision pack
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(5)
(Total 7 marks)
Q3.
In autumn when there is no crop, farm land may be used to grow mustard. The mustard absorbs
nitrates which otherwise can leach out of the soil at this time of the year. The mustard is
ploughed back into the soil just before sowing of the main crop in the spring.
(a) Nitrogen compounds in the mustard plants are made available for the main crop after
ploughing in spring. Describe the role of microorganisms in this process.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(5)
(b) Explain why it is important for the farmer to reduce the leaching of nitrates.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
, Nutrient Cycles Revision pack
(2)
S (c) Plants absorb a number of other nutrients from the soil including phosphates.
Describe why phosphates are needed by a growing plant.
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
(4)
(Total 11 marks)
Q4.
(a) Farmers who grow wheat sometimes leave a field fallow for a year by not growing a crop
in it. The concentration of nitrate ions in the soil decreases when a field is left fallow.
(i) When grass is grown in the field, fewer nitrate ions are lost than when the field is left with
bare soil. Explain why.
______________________________________________________________
______________________________________________________________
(1)
(ii) A crop of leguminous plants such as clover may be grown in the field and then ploughed
in. Explain why less fertiliser would be needed for the wheat crop in the following year.
______________________________________________________________
______________________________________________________________
______________________________________________________________
______________________________________________________________
(2)
(b) The table gives information about the yield and profitability of a wheat crop grown using
different amounts of fertiliser.
