ecosystems and material cycles

Question 1

what is an ecosystem

Answer 1

a community of organisms with all abiotic conditions in an area

Question 2

what is a community

Answer 2

all the organisms of different species living in a habitat

Question 3

population

Answer 3

all the organisms of one species in a habitat

Question 4

how is a belt transect used?

Answer 4

it shows the distribution of organisms along a gradient

Question 5

what is eutrophication

Answer 5

this is when fertilizers leach into water. this causes an excess of nutrients in the water which can lead to the death of many of the species present in the water. the excess nutrients cause algae to grow, blocking light

Question 6

how can fish farms reduce biodiversity

Answer 6

-food is added to the nets to feed the fish, which produce huge amounts of waste. this can leak into open water and cause eutrophication
-they also contain lots of parasites. if they get out, it will kill wild animals

Question 7

what are some conservation schemes to protect at risk species

Answer 7

-protecting a species natural habitat
-protecting the species in safe areas outside their habitat. eg zoos

Question 8

what benefits does maintaining biodiversity have

Answer 8

providing future medicines
-ecotourism
-can provide new jobs

Question 9

what is food security

Answer 9

this is the ability for humans to access sufficient food

Question 10

what are some factors that can affect food security

Answer 10

-increasing consumption of meat and fish
-sustainability-future generations may not have enough food because of how much we are eating today

Question 11

what is desalination

Answer 11

this removes salts from salt water.

Question 12

what is thermal desalination

Answer 12

salt water is heated until the water evaporates. this water is then collected.

Question 13

what is nitrogen fixation

Answer 13

this is the process of turning N2 from the air into nitrogen containing ions

Question 14

what are nitrogen fixing bacteria

Answer 14

they turn nitrogen into ammonia that plants use

Question 15

where are nitrogen fixing bacteria found

Answer 15

root nodules

Question 16

what are decomposers

Answer 16

they decompose proteins and urea into ammonia

Question 17

what are nitrifying bacteria

Answer 17

they turn ammonia in decaying matter into nitrites

Question 18

denitrifying bacteria

Answer 18

turns nitrates into N2 gas

Question 19

how does the method of crop rotation increase the crop growth in soil

Answer 19

-there will be more nitrates in the soil which act as fertilisers for the plant

Question 20

what is crop rotation

Answer 20

this is when crops are moved to different soils once they are grown. in this cycle, a legume plant will be involved
-after the legume plant is moved, the soil that the legume plant was in has lots of nitrates which the new plant can use as fertilisers

Question 21

why is excess fertilisers bad in rivers

Answer 21

it can increase amount of algae and which use up oxygen

Question 22

why are stonefly larvae and freshwater shirimps good indicators of water pollution

Answer 22

as they are very sensitive to the concentration of dissolved oxygen. if there are any of these in a river, it means it is clean

Question 23

is the water dirty or clean if you see blood worms and sludge worms in the water

Answer 23

dirty as these animals are adapted to live in polluted conditions

Question 24

what does it mean if there is lots of lichen growing

Answer 24

this means that the air is really clean. this is because they are sensitive to sulfur dioxide in the atmosphere, so they dont grow where there is lots of sulfur dioxide

Question 25

what will the presence of blackspot fungus indicate

Answer 25

it means air is clean as it wont grow in high levels of sulfur dioxide

Question 26

what three things does the rate of decay depend on?

Answer 26

-temperature
-water content
-oxygen availability