topic 5 (nutrient cycles)

Question 1

what is a natural ecosystem?

Answer 1

ecosystem that hasn’t been changed by human activity

Question 2

what is a saprobiont?

Answer 2

type of decomposer

Question 3

how do saprobionts digest organisms?

Answer 3

secrete enzymes and digest their food externally, and absorb the nutrients they need (extra cellular digestion)

Question 4

what is a symbiotic relationship?

Answer 4

close relationship between members of two different species

Question 5

what are fungi made of?

Answer 5

long thin strands called hyphae, which connect to the plant’s roots

Question 6

what are the benefits of hyphae?

Answer 6

increase the surface area of the plant’s root system, helping to absorb scarce ions
increase water uptake
hold water and minerals around the roots

Question 7

what do fungi obtain from a plant?

Answer 7

organic compounds like glucose

Question 8

what are mycorrhizae?

Answer 8

fungal associations between plant roots and beneficial fungi

Question 9

what is phosphorus used for in organisms?

Answer 9

DNA
RNA
ATP
Phospholipid Bilayer

Question 10

what form is phosphorus found in?

Answer 10

mineral form in sedimentary rocks

Question 11

what are the stages of the phosphorus cycle?

Answer 11

1) phosphate ions in the rocks are released into the soil by weathering
2) phosphate ions are taken into plants via the roots, where mycorrhizae increase the rate phosphorus can be assimilated
3) phosphate ions are transferred by the food chain
4) phosphate ions lost from animals in waste products
5) saprobionts release phosphate ions
6) weathering of rocks releases phosphate ions into seas/lakes/rivers
7) taken up by aquatic producers
8) waste produced by sea birds= guano
9) returns phosphate to the soil

Question 12

what percentage of the air is made of nitrogen?

Answer 12

78%

Question 13

how can plants/animals obtain nitrogen?

Answer 13

microorganisms convert nitrogen gas to nitrogen containing substances which can be absorbed

Question 14

what biological molecules is nitrogen found in?

Answer 14

proteins, ATP, nucleic acids

Question 15

what are the 4 stages of the nitrogen cycle?

Answer 15

nitrogen fixation

ammonification

nitrification

dentrification

Question 16

what happens in nitrogen fixation?

Answer 16

nitrogen gas in the atmosphere is converted into nitrogen containing compounds

turn nitrogen into ammonium

Question 17

what happens in ammonification?

Answer 17

nitrogen compounds from dead organisms/animal waste are turned into ammonia by saprobionts, goes onto form ammonium ions

Question 18

what happens in nitrification?

Answer 18

ammonium ions in the soil are changed into nitrogen compounds which can be used by plants

ammonium ions into nitrites into nitrates

Question 19

what is dentrification?

Answer 19

nitrates in the soil are converted into nitrogen gas by dentrifying bacteria

use nitrates in the soil to carry out respiration and produce nitrogen gas

happens in anaerobic conditions

Question 20

how do microorganisms produce nitrates?

Answer 20

nitrogen containing compounds converted into ammonia by saprobionts
ammonia converted into nitrite 
nitrite converted into nitrate 
by nitrifying bacteria 
nitrogen converted to ammonia 
by nitrogen fixing bacteria

Question 21

when are nutrients lost?

Answer 21

when crops are harvested or animals are removed from the land

Question 22

what are the two types of fertilisers?

Answer 22

artificial and natural

Question 23

what are artificial fertilisers?

Answer 23

inorganic- contain pure chemicals

Question 24

what are natural fertilisers?

Answer 24

organic, eg manure, composted vegetables

Question 25

what is leaching?

Answer 25

when water soluble compounds in soil are washed away

Question 26

when does applying fertilisers lead to leaching?

Answer 26

when more fertiliser is applied than a plant can need/use

especially before heavy rainfall

Question 27

when is leaching more likely?

Answer 27

when using chemical fertilisers

contain inorganic ions that are fairly soluble, so excess minerals not immediately used are more likely to leach

Question 28

when is leaching less likely?

Answer 28

when using natural fertilisers
nitrogen/phosphorus contained in organic molecules that need to be decomposed before they can be absorbed
release into soil more controlled so leaching less likely

Question 29

are phosphates or nitrates more likely to leach?

Answer 29

nitrates, as phosphates are less soluble in water

Question 30

what happens in the process of eurotrophication?

Answer 30

mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds/rivers

large amounts of algae block light from reaching the plants below

eventually plants die as they cannot photosynthesise enough

bacteria feed on dead plant matter- more bacteria reduce the oxygen concentration by carrying out aerobic respiration

fish and other aquatic organisms die due to a lack of dissolved oxygen