nutrient cycles and fertilisers

Question 1

define detritivores

Answer 1

animals such as worms or woodlice that eat and digest detritus. they break tissues down to increase their surface area for action by saprobionts.

Question 2

define saprobionts

Answer 2

secrete enzymes for extracellular digestion. create small soluble molecules that diffuse into saprophyte requires specific conditions.

Question 3

what conditions do saprobionts require

Answer 3

aerobic, non acidic, warm

Question 4

what is mycorrhizae

Answer 4

associations between certain types of fungi and the roots of plants.

Question 5

function of mycorrhizae

Answer 5

fungi act like extensions of the plant. increase the surface area for absorption of water and minerals. hold water and nutrients near roots and help take up inorganic ions more readily.

Question 6

3 effects of nitrogen containing fertilisers

Answer 6

reduced species diversity
leaching
eutrophication

Question 7

how does N fertiliser reduce species diversity

Answer 7

favours growth of grasses, nettles, rapidly growing species which out compete other species.

Question 8

2 negatives of N fertiliser causing leaching

Answer 8

high nitrate ion levels in water sources may be harmful to humans
high nitrate ion concentration leads to eutrophication.

Question 9

cause of eutrophication

Answer 9

fertilisers leach off farm fields into surrounding water course and sewage. contains dissolved minerals, such as nitrates and phosphates.

Question 10

what is eutrophication

Answer 10

effects of increase nutrients concentration on aquatic ecosystems.

Question 11

two types of fertiliser

Answer 11

organic (farmyard manures)
inorganic (manufactured containing N and P)

Question 12

4 advantages of organic fertiliser

Answer 12

steady supply of nutrients to plants
adds structure to soil (hummus)
useful means of disposing farm waste
nutrients not readily leached

Question 13

3 disadvantages of organic fertiliser

Answer 13

offensive smells
may be difficult to spread
mineral release slow

Question 14

3 advantages of inorganic fertiliser

Answer 14

conc form of nutrients - cost effective
nutrients release rapidly into soil
clean chemicals that lack odour of organic manure

Question 15

4 disadvantages of inorganic fertiliser

Answer 15

readily leached from soil
can damage trophic levels in ponds/lakes
expensive to manufacture/buy
risk of fertiliser spreading to other areas

Question 16

effect of eutrophication

Answer 16

excessive algal bloom
can reduce oxygen levels due to decomposition of dead algae using up oxygen

Question 17

order of nitrogen cycle

Answer 17

atmospheric N2
nitrogen fixation
NH3
nitrification
NO2-
NO3-
assimilation (active transport)
plants
animals
ammonification
NH3

Question 18

what is the process called of NO3- becoming atmospheric N2 called

Answer 18

denitrification

Question 19

conditions of denitrification

Answer 19

anaerobic

Question 20

conditions of both nitrogen fixing bacteria and nitrifying bacteria

Answer 20

aerobic

Question 21

where are nitrogen fixing bacteria found

Answer 21

root nodules of legumes
soil

Question 22

where are nitrifying bacteria found

Answer 22

soil

Question 23

process of animal debris becoming ammonia

Answer 23

ammonification

Question 24

process of atmospheric N2 becoming NH3

Answer 24

nitrogen fixation

Question 25

process of NH3 becoming nitriles and nitrates

Answer 25

nitrification

Question 26

which 4 farming practices are used to help the nitrogen cycle

Answer 26

plough (increases O2)
crop rotation
NPK fertiliser
drainage