The nutrient cycle

Question 1

Why is Nitrogen important?

Answer 1

1) Used in the production of Amino Acids and Proteins

2) Used to make bases in DNA

Question 2

What are the forms of inorganic N?

Answer 2

N2, NO2, NH3

Question 3

What are the stages of the N cycle?

Answer 3

1) Nitrogen fixation
2) Nitrification
3) Assimilation
4) Ammonification
5) Denitrification

Question 4

What is nitrogen fixation?

Answer 4

N2 + 6H -> 2NH3 -> NH4+ this requires nitrogen fixing bacteria, Enzyme: nitrognase

Question 5

Where do nitrogen fixing bacteria live?

Answer 5

Bases of the roots of leguminous plants

Question 6

How else can Nitrogen be fixed?

Answer 6

The Haber Process (N2 + 3H2 -> 2NH3)

Spread as nitrogen fertiliser

Question 7

What is nitrification?

Answer 7

NH4+ -> NO3- by nitrifying bacteria

Exothermic process so bacteria make ATP

Question 8

What is assimilation?

Answer 8

The uptake of NO3- ions by plants to make amino acids and proteins
Active transport

Question 9

What is ammonification?

Answer 9

The use of microbial saprobionts to break down dead plants, animals and waste which releases NH4+ back into the soil

Question 10

What is denitrification?

Answer 10

The conversion of NO3- ions to N2

Question 11

What should happen when solar radiation reaches the earth?

Answer 11

Some is reflected back into space and some is absorbed in the atmosphere and some reaches the earth

Question 12

What is the greenhouse effect?

Answer 12

The heating affect caused by the greenhouse gases preventing radiation of heat from the earth to space

Question 13

What are the greenhouse gases?

Answer 13

Carbon dioxide, sulphur dioxide and methane

Question 14

What are the arguments against global warming?

Answer 14

The earth has always shown periodic fluctuation in temperature therefore we cannot say that humanity is to blame.

Question 15

What are the arguments for global warming?

Answer 15

Atmospheric levels have increased since the start of the industrial revolution which seem to be linked to the increasing temperature.

Question 16

What are the consequences of global warming?

Answer 16

1) Alteration in the distribution of species
2) Melting of polar ice caps thus increasing sea levels
3) Increase temp means a decrease in crop yield

Question 17

What are the benefits of global warming?

Answer 17

Increased temperature thus increased rain fall thus increase in possible harvest (3rd world countries)

Question 18

Where is phosphorous found?

Answer 18

In soil and rocks as phosphates (PO43-)

Question 19

What is eutrophication?

Answer 19

The build up of excess nutrients such as nitrogen a phosphate which negatively effects an ecosystem

Question 20

What are the steps in eutrophication?

Answer 20

1) Excess fertiliser to be added to soil
2) Excess fertiliser transported to other parts of the community
3) Algae and bacteria experience exponential growth
4) All available O2 is used by algae and bacteria
5) Other species in the eco system die as a result

Question 21

What are the uses of phosphorous?

Answer 21

1) DNA

2) ATP