U1T4 - Keywords (3)

Question 1

Excretion

Answer 1

Removal of waste matter from an organism. (Urine)

Question 2

Egestion

Answer 2

Removal of undigested food from an organism. (Faeces)

Question 3

Nitrogen Fixation

Answer 3

Converts nitrogen gas into nitrogen containing compounds. Has 3 main methods (nitrogen fixing bacteria, haber process + lightning)

Question 4

The Haber Process

Answer 4

Used to make fertilisers added to soil. Nitrogen reduced to create ammonia. Industrial method.

Question 5

Nitrogen-Fixing Bacteria

Answer 5

Free living bacteria reduce nitrogen gas from air (air pockets in soil) into ammonia, used to synthesise amino acids for formation of proteins. Catalyse reaction with nitrogenase so it can take place at 20c unlike high temps required in Haber process. Enriches soil (farmers grow legumes + let them decay to add N2)

Question 6

Ammonification

Answer 6

Saprobiotic bacteria/fungi feed on dead organisms/organic waste, releasing ammonia (NH4+) in water. Aided by earthworms as feed on dead organisms, breaking into small pieces (Large SA) + distributes dead material through soil.

Question 7

Nitrification

Answer 7

Requires O2 so only occurs rapidly in well aerated soils/well oxygenated waters. 2 stages by diff nitrifying bacteria (both chemoautotrophs)

Question 8

Chemoautotrophs

Answer 8

Derive energy for synthesis of organic molecules from oxidation reactions in nitrification.

Question 9

Active Transport

Answer 9

Energy requiring process so proceeds best in aerobic conditions.

Question 10

Leaching

Answer 10

When nitrates are washed out of soils due to heavy rains.

Question 11

Denitrification

Answer 11

Denitrifying bacteria (Pseudomonas) are anaerobes + reduce nitrate (NO3-) to atmospheric nitrogen (N2) + O2 which can be used by bacteria in aerobic resp whilst N2 escapes into atmosphere. Leads to loss of nitrates from soil + can reduce soil fertility. Occurs in soils with high nitrate content but also anaerobic conditions usually caused by waterlogging.

Question 12

Fossilisation

Answer 12

Dead organisms preserved in environments hostile to decay. (Anaerobic Conditions) Fossil fuels (coal, peat) contain locked in carbon not released as decay + decomp couldn’t occur. Carbon released by combustion.

Question 13

Mineralisation

Answer 13

Decay + decomp by saprobiotic organisms recycling N2 in dead organisms, excreta + faeces to usable inorganic form (nitrate) 2 stages (ammonification + nitrification)

Question 14

Nitrogenase

Answer 14

Enzyme of nitrogen-fixing bacteria that catalyses reduction of nitrogen to ammonia.

Question 15

Putrifying (Decay) Bacteria

Answer 15

Bacteria involved in putrefaction of living matter. Recycles nitrogen from dead organisms.

Question 16

Organic Pollution

Answer 16

Chemical pollution caused by carbon pollutants (manure/sewage)

Question 17

Indicator Species

Answer 17

Living organisms which can show pollution by being present or absent.

Question 18

Extensive Farming

Answer 18

Using more land with lower yield to produce same amount of food.

Question 19

Intensive Farming

Answer 19

Using less land, with lots of fertiliser + machinery.

Question 20

Sustainable Farming

Answer 20

Farming in ways based on understanding ecosystems.

Question 21

Biodegradable

Answer 21

Capable of being decomposed by bacteria/other living organisms + so avoiding pollution.

Question 22

Anaerobic

Answer 22

Not using much O2 to respire.