Ecology and Biological Resources

Question 1

Define habitat

Answer 1

Place where an organism lives e.g. Rocky shore or a field

Question 2

Define population

Answer 2

All the organisms of one species in a habitat

Question 3

Define community

Answer 3

All different species in a habitat

Question 4

Define ecosystem

Answer 4

All the organisms living in a particular area and all the non-living conditions e.g. Temp / climate

Question 5

What is a quadrat

Answer 5

Square frame that encloses a known area

Used to estimate population size

Question 6

Process of quadrat

Answer 6

Place quadrat (e.g. 1m) at random point
Count all organisms in quadrat
Multiply by total area (in m)

Question 7

Problems with quadrats

Answer 7

May not be representative as it is random

May not be accurate so use bigger quadrats at multiple places and find mean

Question 8

Explain how to use a quadrat to investigate distribution of organisms

Answer 8

Mark out line in area

Collect data along the line using quadrats placed next to each other (called transects)

Question 9

what is a producer?

Answer 9

begging of food chain

produces their own food

Question 10

what are decomposers ?

Answer 10

end of food chain

break down dead material and waste

Question 11

what is a trophic level ?

Answer 11

each stage of good chain (e.g. producer)

Question 12

trophics of a food chain

Answer 12

producer
primary/secondary/tertiary consumer
decomposer

Question 13

explain why not all energy is transferred in food chains

Answer 13

some parts aren’t eaten (roots/bones)
some parts are indigestible (e.g. fibre)
lots is used to power life processes
most is eventually lost as heat

Question 14

describe the water cycle

Answer 14

water evaporates (sun)
plants transpire water also
warm water cools and condenses to form clouds
water falls as precipitation

Question 15

describe the carbon cycle

Answer 15

plants use CO² to photosynthesise
animals eat plants and die (as well as plants) and are broken down by decomposers
decomposers/animals/plants all respire, giving out CO²
products like wood and fossil fuels are burned (combustion) releasing CO²

Question 16

describe decomposers (N² cycle)

Answer 16

break down proteins (dead matter) and urea and turn into ammonia

Question 17

describe nitrifying bacteria

Answer 17

turns ammonia into nitrates

Question 18

describe nitrogen-fixing bacteria

Answer 18

turns atmospheric nitrogen into nitrogen compounds

Question 19

describe denitrifying bacteria

Answer 19

turns nitrates into nitrogen gas (no benefit)

Question 20

where do the nitrogen bacteria live?

Answer 20

soil or nodules on plant roots

Question 21

how does lightning play a part in the nitrogen cycle?

Answer 21

has enough energy to make nitrogen gas react with oxygen to form nitrates

Question 22

how is carbon monoxide released?

Answer 22

usually car emissions (when hydrocarbons burn without enough oxygen)

Question 23

why is carbon monoxide poisonous ?

Answer 23

combines with red blood cells and prevents them from carrying oxygen

Question 24

how are cars made to reduce carbon monoxide emissions ?

Answer 24

fitted with catalytic converters that turn carbon monoxide int carbon dioxide

Question 25

what causes acid rain?

Answer 25

sulfur dioxide (come from sulfur impurities in fossil fuels) which reacts with rain clouds to form dilute sulfuric acid

Question 26

why is acid rain harmful?

Answer 26

causes lakes to become more acidic, killing organisms as they are sensitive to pH changes
kills trees by damaging leaves releasing toxic substances in soil, making it hard to take up nutrients

Question 27

how has human activity increased CO² levels ?

Answer 27

car exhausts and burning fossil fuels

deforestation

Question 28

how has human activity increased methane levels?

Answer 28

increase of rice growing and cattle rearing

Question 29

how has human activity increased nitrous oxide levels?

Answer 29

released from soils after fertilisers used

vehicle engines and industry

Question 30

what is CFCs?

how has human activity increased CFCs levels?

Answer 30

man made chemical previously used for aerosols and fridges

most countries agreed to stop however may still get released

Question 31

describe eutrophication

Answer 31

fertilisers enter lake, adding nutrients
algae grow fast and block light
plants can’t photosynthesise so die
with more food, microorganisms feed on dead plants and reproduce rapidly, eventually depleting oxygen
organisms in lake die

Question 32

explain another way of eutrophication

Answer 32

sewage goes into lake
sewage contains phosphates and nitrates
same process as fertilisers

Question 33

how does deforestation affect leaching ?

Answer 33

trees removed and nutrients get leeched away but don’t get replaced, leaving infertile soil

Question 34

how does deforestation affect soil erosion ?

Answer 34

tree roots hold soil together

when trees removed, soil can be washed away by rain and leave infertile ground

Question 35

how does deforestation affect water cycle ?

Answer 35

trees stop rainwater reaching rivers too quickly
when they’re cut, rainwater flows straight into rivers, can cause floods
also makes local climate drier as trees transpire

Question 36

how does deforestation affect carbon cycle ?

Answer 36

when trees cut and burned, it releases CO²

fewer trees means less photosynthesis so less CO² being used up