topic 9 ecosystems

Question 1

levels of organisation

Answer 1

individual - single organism
population - all the organisms of one species in a habitat
community - all organisms of a different species living in a havitsf
ecosystem - a community of organisms along with the non living (abiotic) conditions

Question 2

interdependence definition

Answer 2

organisms depend on each other

Question 3

what is mutualism

Answer 3

a relationship between two organisms from which both organisms benefit

Question 4

what is a parasite

Answer 4

live very closely with a host
takes what it needs to survive but the host doesn’t benefit
e.g fleas feed on the host blood but doesn’t offer anything in return

Question 5

abiotic factors

Answer 5

temperature
water availability
light intensity
levels of pollutants

Question 6

biotic factors

Answer 6

competition
predation
disease

Question 7

core practical - distribution

Answer 7

place a 1m^2 quadrant on the ground at a random point
count al organisms you’re interested in within the quadrant
repeat lots of times steps 1 and 2
find mean by divide total number of organisms by number of quadrants
repeat whole process again
compare the two means

Question 8

belt transect core practical

Answer 8

mark a line in the area u wanna study
collect data along the line using quadrants placed next to each other
repeat steps 1 and 2 then find mean number for each quadrant

Question 9

what is eutrophication

Answer 9

fertilisers enter water adding excess nitrates
excess nitrates cause algae to grow fast and block out the light
plants can’t photosynthesise due to lack of light and begin to die and decompose
decomposers feed on the plants and use up the oxygen
organisms like fish that need oxygen for aerobic respiration die

Question 10

fish farming advantages

Answer 10

preserves the wild population
selectively breed to ensure high quality fish
control water quality

Question 11

fish farming disadvantages

Answer 11

disease spreads easier
fish excrete waste a lot and that goes into the ecosystem spreading bacteria

Question 12

introducing non native species advantage

Answer 12

pest control

Question 13

introducing non native species disadvantage

Answer 13

no natural predators so population booms as they can outcompete

Question 14

biological levels affecting food security

Answer 14

increase in consumption of meat and fish which increases animal farming (overfishing, people get rich and want more meat and fish, takes longer than growing crops)

environmental changes caused by human activity (burning fossil fuels, climate change, soil pollution)

sustainability

new pests and pathogens

Question 15

carbon cycle

Answer 15

green plants use carbon from co2 to make fats and proteins

eating passes the carbon compounds in plants to animals in a food chain

both animal and plants respiration
release co2 back out into air
they eventually die and decompose

microorganisms break down the material and release co2

useful plant and animal products are burned and releases co2 in the air

Question 16

water cycle

Answer 16

energy from the sun makes water evaporate and it turns into water vapour
water also evaporates from plants (transpiration)

warm water vapour carried upwards
cooks and condenses to form clouds

water falls from clouds as precipitation

drains into sea

Question 17

nitrogen cycle

Answer 17

nitrogen in the air turns into nitrates
plants absorb the mineral ions from the soil and use the nitrogen in them to make proteins
nitrogen is passed along the food chain

decomposers break down proteins in rotting plants and animals which returns nitrogen to the soil

Question 18

nitrifying bacteria definition

Answer 18

turn ammonia in decaying matter into nitrites and then nitrates

Question 19

nitrogen fixing bacteria

Answer 19

turns nitrogen gas into ammonia which forms ammonium ions

Question 20

denitrifying bacteria

Answer 20

turns nitrates back into nitrogen gas
often found in waterlogged soils

Question 21

nitrogen fixing bacteria on nodules

Answer 21

some live in nodules on the roots of legume plants

when the plants decompose, nitrogen stored in their nodules is returned to the soil

they can also leak out of nodules during plant growth

it is a mutualistic relationship with the bacteria as they get food from the plant and the plant gets nitrates to make into proteins

Question 22

crop rotation

Answer 22

different crops are grown each year on a cycle
usually includes a nitrogen fixing crop (peas or beans) to put nitrates back into the soil for another crop to use a following year

Question 23

fertilisers

Answer 23

animal manure or compost return nutrients left in a plant through decomposition

artificial fertilisers containing nitrates can also be used

Question 24

indicator species (water)

Answer 24

clean - stonefly larvae
polluted - bloodworms and sludge worms

Question 25

indicator species (air)

Answer 25

clean air - black spot fungus
polluted air - lichen further away from city

Question 26

disadvantages of indicator species method

Answer 26

factors other than pollution can affect it
no numerical accurate figures of how pollution is present

chemical tests and dissolved oxygen meters work better
so do electronic meters to show concentration of sulfur dioxide