topic 9 - ecosystems and material cycles

Question 1

how does increasing human population affect food security levels?

Answer 1

increases food security

Question 2

how does increased animal farming and meat and fish consumption affect food security levels?

Answer 2

increased consumption, less energy and less biomass every time you move up the food chain, there’s also a risk of over-fishing and there not being enough in future

Question 3

how does the impact of new pests and pathogens affect food security levels?

Answer 3

causes damage to crops, decreases food security, wipes out large numbers of crops and reduced yield

Question 4

how do environmental changes caused by human activity affect food security levels?

Answer 4

burning fossil fuels increases global warming and affects growth of crops which could reduce yields

Question 5

how do sustainability levels affect food security levels?

Answer 5

increase in crops and growth to grow biofuels, take up land that could be used for crops, high input costs of farming makes crops expensive to grow

Question 6

how are nitrates made available for plant uptake?

Answer 6

ammonia is converted to nitrates by nitrifying bacteria in the soil

Question 7

what is the role of bacteria in the nitrogen cycle?

Answer 7

they convert atmospheric nitrogen into nitrates

Question 8

what is the importance of the nitrogen cycle?

Answer 8

essential for the formation of amino acids, which form proteins

Question 9

what is the importance of the carbon cycle?

Answer 9

it can affect the amount of heat contained in the atmosphere
moves carbon from the air between the ocean and the atmosphere

Question 10

how is the carbon cycle involves in the role of micro organisms as decomposers?

Answer 10

decomposers break down the dead minerals from plants and other organisms, and release carbon dioxide into the atmosphere

Question 11

what is the importance of the water cycle?

Answer 11

enables availability of water for all living organisms

regulated weather patterns on our planet

Question 12

how is the water cycle involves in the production of potable water?

Answer 12

removes salt and minerals from seawater (water desalination)

Question 13

how does temperature, water content and oxygen affect the rate of decomposition in food preservation?

Answer 13

temperature - lower temperatures decrease the rate of decomposition
water content - drying foods removes the water that micro organisms need to survive, as does adding salt or sugar - causes micro organisms to lose water by osmosis
oxygen availability - airtight storage stops micro organisms getting in, they are sealed and sterilised

Question 14

which indicator species indicate:
polluted water
clean water
air quality

Answer 14

polluted water - bloodworm, sludgeworm
clean water - stonefly, freshwater shrimps
air quality - lichen, blackspot fungus on roses

Question 15

how does the effect of water content, temperature and oxygen availability, affect the rate of decomposition in composting?

Answer 15

temperature - warmer temperatures speed up enzyme controlled reactions, decay happens faster, enzymes denature if temperatures are too high
water content - decays faster in moist environments as the organisms involved in decay need water
oxygen availability - rate increases when there is a large supply of oxygen, microorganisms need oxygen to respire

Question 16

what are some benefits of reforestation?

Answer 16

provides food and shelter for lots of different species
helps restore biodiversity
if there are lots of types of trees there is higher biodiversity compare to just one type of tree

Question 17

what are some benefits of the conservation of animal species?

Answer 17

protects natural habitats
protects species in face areas outside their natural habitats
the use of seed banks store and distribute seeds of rare and endangered plants

Question 18

what are some benefits of maintaining local and global biodiversity?

Answer 18

protecting human food supply - over fishing has greatly reduced fish stocks in oceans
ensuring minimal damage to food chains - conserving species to help other survive
provides new jobs
ecotourism - brings money to biodiverse areas

Question 19

what are some advantages and disadvantages of eutrophication?

Answer 19

ad - none
dis - nitrates are put into fields as fertilisers, if too much is added and then it rains, the nitrates find their way towards rivers and lakes
- causes algae to grow fast and block out the light
- plants cannot photosynthesise without light and so they die
- with more food available, organisms will increase and so will oxygen consumption
- organisms cannot then respire without oxygen and so they eventually also die

Question 20

what are some positives of the introduction of non-indigenous species?

Answer 20

faster growth and reproduction rates
higher ecological tolerance
contributes to ecosystems stability
increases biodiversity

Question 21

what are some negatives of the introduction of non-indigenous species?

Answer 21

causes competition for food and shelter
non-indigenous species could be stronger and so indigenous species may die out ‘
they may bring about new diseases into the habitat

Question 22

what are some positives of fish farming?

Answer 22

fish are protected from predators
competing species cannot enter the farm
indoor farmed fish are protected from weather changes

Question 23

what are some negatives of fish farming?

Answer 23

produce huge amounts of waste from food in nets given to the fish
food and waste can leak into open water causing eutrophication
predators get trapped and die
fish can escape into the wild causing problems to non indigenous species

Question 24

how do you calculate the efficiency of energy between trophic levels?

Answer 24

efficiency = (energy transferred to next level / energy available at previous level) x 100

Question 25

how do you calculate percentage of biomass between trophic levels?

Answer 25

efficiency = (biomass transferred to next level / biomass available at previous level) x 100

Question 26

what is the energy transferred to at each trophic level?

Answer 26

less useful forms

Question 27

what does the energy transferred at each trophic level affect?

Answer 27

number of organisms at each tropic level
limits length of food chain
determines the shape of the pyramid of biomass in an ecosystem

Question 28

what are the trophic levels?

Answer 28

1. producers
2. primary consumers
3. secondary consumers
4. tertiary comsumers