ecology

Question 1

Population

Answer 1

all the organisms of one species in a habitat

Question 2

habitat

Answer 2

place where an organism lives

Question 3

community

Answer 3

all different species in one habitat

Question 4

biodiversity

Answer 4

variation of species and organisms on earth

Question 5

why is only 10% of energy transferred through trophic levels

Answer 5

• not all bits of organism eaten/digested
• energy lost in movement
• energy lost in faeces

Question 6

carbon cycle stage 1

Answer 6

co2 absorbed by plants in photosynthesis

Question 7

carbon cycle stage 2

Answer 7

co2 used to make glucose and proteins

Question 8

carbon cycle stage 3

Answer 8

plants respire, releasing co2

Question 9

carbon cycle stage 4

Answer 9

plants eaten by animals, co2 in their system

Question 10

carbon cycle stage 5

Answer 10

animals respire, release co2

Question 11

carbon cycle stage 6

Answer 11

plants and animals die, decomposed by bacteria and microorganisms

Question 12

carbon cycle stage 7

Answer 12

microorganisms respire

Question 13

carbon cycle stage 8

Answer 13

combustion of fuels releases co2

Question 14

nitrogen cycle stage 1

Answer 14

nitrogen fixation: nitrogen in air is turned into ammonia then into nitrates by nitrogen fixing bacteria or lightning (found in soils and plant nodules)

Question 15

nitrogen cycle stage 2

Answer 15

the nitrates are used by the plant to build up proteins. animals feed on plants and therefore nitrogen is passed on in that way

Question 16

nitrogen cycle stage 3

Answer 16

if the animals or plants die, decomposers like bacteria or fungi return nitrogen to the soil in the form of ammonium ions

Question 17

nitrogen cycle stage 4

Answer 17

plants can’t absorb ammonium ions, so nitrification takes place

Question 18

nitrogen cycle stage 5

Answer 18

nitrification: nitrifying bacteria breaks down ammonium ions into nitrites then nitrates which can be taken up by plants again

Question 19

nitrogen cycle stage 6

Answer 19

denitrification: nitrates in the soil can be converted back into nitrogen gas by denitrifying bacteria

Question 20

nitrogen cycle stage 7

Answer 20

denitrification happens in waterlogged/ aerobic conditions, so farmers can prevent this by ploughing the soil to increase aeration

Question 21

eutrophication/ leaching

Answer 21

fertiliser rich in nitrates ends up in waters, allowing the algae to grow rapidly and form an algal bloom

Question 22

eutrophication/ leaching stage 2

Answer 22

algal bloom stops light entering water and all plants under algae die.

Question 23

eutrophication/ leaching stage 3

Answer 23

algae begins to run out of nutrients and dies, so bacteria decomposes the algae releasing trapped nitrates and starting the cycle again

Question 24

eutrophication/ leaching stage 4

Answer 24

the decomposers increase in number, using all the oxygen so no other organisms can survive

Question 25

effects of water sewage pollution

Answer 25

- increase in growth of aerobic bacteria - they reduce availability of dissolved oxygen in water - aquatic organisms sensitive to oxygen levels die, leaving only organisms that can survive at low concs of oxygen - decrease in biodiversity - can also increase pathogenic bacteria

Question 26

consequences of sulfur dioxide pollution

Answer 26

caused by combustion of fossil fuels in car engines, dissolves in water to create acid rain effects of acid rain: - leaches minerals and nutrients out the soil, killing plants - damages waxy cuticle, less absorption of mineral ions - acidifies rivers and lakes, resulting in deaths of aquatic organisms - corrodes metal and steel

Question 27

consequences of carbon monoxide pollution

Answer 27

incomplete combustion of fossil fuels produces carbon monoxide, which binds to haemoglobin and reduces capacity of RBCs to carry oxygen effects: - constant tiredness - emphysema due to insufficient oxygen - if pregnant, hinders growth of foetus