biology paper 2- ecology and environment Flashcards Preview

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Flashcards in biology paper 2- ecology and environment Deck (33):
1

define habitat

the place where an organism lives

2

define population

all the organisms of one species in a habitat

3

define community

all the different species in a habitat

4

define an ecosytem

all the organisms living in a particular area and all the non-living conditions

5

what are quadrats used for?

used to sample the distribution of organisms in their habitats
-used to estimate the population of an organism in different areas

6

how do you complete a quadrat?

- measure area of filed
- place a 1m^2 quadrat on the ground at a random point
-count all the organisms int he area
- place results in table
- multiply the number of organisms by the total area

7

how does the sample size affect the accuracy of the estimate?

the bigger the sample, the more accurate the estimate of the population
- better to use the quadrat at several points to get an average value for the number of organisms in 1m^2, then multiply by the total area

8

how can quadrats be used to investigate the distribution of organisms?

-laid out along a line called a transect
- make out the area you want to study
- collect data along the line using quadrats placed next to each other

9

producer?

makes its own food through photosynthesis

10

consumer?

eats producers- primary, secondary, tertiary

11

decomposer?

organisms that eat and breakdown dead and dying material and waste

12

what are pyramids of biomass?

shows the mass of living materials at that stage in the food chain

13

what are pyramids of numbers?

shows the number of organisms at that stage of the food chain

14

what are pyramids or energy transfer?

shows the amount of energy transferred to each trophic level in a food chain

15

how much energy is transferred to each trophic level?

10% because some parts of food are eaten and energy is taken in
some parts of food are indigestible so come out as waste
some is used for respiration
energy is lost as heat

16

what is the carbon cycle?

shows how carbon is recycled
-respiration use sugars that react with oxygen to produce CO2
- photosynthesis - produces carbohydrates, fats, proteins and O2 from CO2
- combustion- fuels that react with oxygen to release CO2, water and energy
- Decomposition- bacteria and fungi break down waste and dead remains. this releases energy, water and CO2

17

what are the effects of carbon monoxide?

1- when fossil fuels are burnt without enough oxygen they produce carbon monoxide
2- it's poisonous as it combines with red blood cells and prevents them from carrying oxygen
3- mostly released in car emissions. most modern cars are fitted with catalytic converters that turn CO into CO2

18

what are the effects of sulfur dioxide?

- caused by burning fossil fuels come from sulfur impurities in the fossil fuels
- SO2 mixes with rain clouds to form dilute sulfuric acid which falls as acid rain
- internal combustion engines in cars and power stations are the main causes of acid rain

19

what does acid rain do?

1- causes lakes to become acidic. Severe effect on the lake's ecosystem. Many organisms are sensitive to change sin pH and can't survive in more acidic conditions=plants and animals die
2- acid rain can kill trees. the acid damages leaves and releases toxic substances from the soil, making it hard for the trees to take up nutrients

20

what are the green house gases and how are they produced?

1- CO2= released by humans into atmosphere from industrial processes, car exhausts, fossil fuels, deforestation
2- METHANE- produced naturally-rotting plants in marshland, rice growing and cattle rearing
3- NITROUS OXIDE- released naturally by bacteria in soils and the ocean, more after fertiliser is used, vehicle engines
4- CFCs- man-made chemicals that were once used in aerosol sprays and fridges, they damage the ozone layer and prevent UV radiation reaching Earth

21

what's the greenhouse effect?

greenhouse gases make a layer around the Earth
the layer traps some of the energy and reflects it back to Earth
this causes an increases in temperature known as global warming
CONSEQUENCES- Global warming (type of climate change), drought, melting ice caps, water levels rise, plant and animal death

22

what is eutrophication?

the build-up of nutrients in a waterway including nitrates and phoshates

23

where do these nutrients come from?

sewage
insecticide spraying
excess fertiliser use

24

how does eutrophication do damage to rivers and lakes?

1- fertilisers enter the water adding extra nutrients
2- these cause algae to grow fast and block out the light
3- plant's can't photosynthesise due to lack of light and start to die
4- with more food available, microorganisms that feed on dead plants increase in number and deplete all the oxygen in the water
5- organisms that need oxygen, like fish, die

25

how does deforestation affect soil?

1- leaching- trees take up nutrients from the soil before they can be washed away by rain, but return them to the soil when leaves die
- so when trees are removed nutrients get leached away but don't get replaced, leaving infertile soil
2- soil erosion- tree roots hold the soil together
- when trees are removed, soil can be washed away by the rain leaving infertile ground

26

how does deforestation affect the water cycle?

-trees stop rainwater reaching rivers too quickly
-when they're removed, rainwater can run straight into rivers- lead to flooding
-transpiration from trees releases some of the rainwater back into the atmosphere so when cut down can make the local climate drier

27

how does deforestation affect the balance of carbon dioxide and oxygen?

- forest take up CO2 by photosynthesis, store it in wood, and slowly release it when they decompose
-when trees are cut down and burnt, the stored carbon is released at once as CO2 contributing to global warming
-fewer trees means less photosynthesis so less oxygen released. this causes oxygen level in the atmosphere to drop

28

describe the water cycle

water on earth is constantly recycled:

1- heat from the Sun makes water evaporate from the land and sea, turning it into water vapour. Water also evaporates from plants- transpiration

2- the warm water vapour is carried upwards (as warm air rises). When it gets higher up it cools and condenses to form clouds

3- water falls from the clouds as precipitation: rain, snow or hail, and is returned to the land and the sea

29

describe the nitrogen cycle

1- the atmosphere contains about 78% nitrogen gas, N2. This is very unreactive and so it can't be used directly by plants or animals

2- nitrogen is needed for making proteins for growth, so living organisms need to get it:

3- plants get their nitrogen from the soil, so nitrogen in the air has to be turned into nitrogen compounds (nitrates) before plants can use it. Animals can only get proteins by eating plants or each other

4-Nitrogen fixation is the process of turning nitrogen gas from the air into nitrogen compounds in the soil which plants can use:

-> LIGHTNING- there's so much energy in a bolt of lightning that it's enough to make nitrogen react with oxygen in the air to give nitrates
-> NITROGEN-FIXING BACTERIA in roots and soil

5- 4 different types of bacteria involved in the nitrogen cycle
a) DECOMPOSERS: break down proteins- in rotting plants and animals, and urea (in animal waste) and turn them into ammonia- nitrogen compound
b) NITRIFYING BACTERIA: turn ammonia in decaying matter into nitrates
c) NITROGEN-FIXING BACTERIA: Turn atmospheric N2 into nitrogen compounds that plants can use
d) DENITRIFYING BACTERIA: turn nitrates back into N2 gas- no benefit to living organims

some live in the soil and some live in NODULES on plant roots

30

what are the two ways of nitrogen fixation?

-> LIGHTNING- there's so much energy in a bolt of lightning that it's enough to make nitrogen react with oxygen in the air to give nitrates
-> NITROGEN-FIXING BACTERIA in roots and soil

31

what are the 4 different types of bacteria involved in the nitrogen cycle?

a) DECOMPOSERS: break down proteins- in rotting plants and animals, and urea (in animal waste) and turn them into ammonia- nitrogen compound
b) NITRIFYING BACTERIA: turn ammonia in decaying matter into nitrates
c) NITROGEN-FIXING BACTERIA: Turn atmospheric N2 into nitrogen compounds that plants can use
d) DENITRIFYING BACTERIA: turn nitrates back into N2 gas- no benefit to living organims

32

where do the bacteria live in the nitrogen cycle?

some of these bacteria live in the soil and some of them live in NODULES on plant

33

what are other causes of eutrophication?

1-pollution by sewage- it contains lots of phosphates from detergents, e.g. washing powder. It also contains nitrates from urine and faeces.
2- these extra nutrients cause eutrophication in the same way fertilisers do