Section 8- Ecology and the Environment, P1 Flashcards
Define Habitat:
The place where an organism lives
-e.g. a field
Define Population:
All the organisms of one species in a habitat
Define community:
All the different species in a habitat
Define ecosystem:
All the organisms living in a particular area and all the non-living(abiotic) conditions
-e.g. temperature, climate
What cause changes in the environment?
- abiotic(non-living) and biotic(living) factors
- the changes affect communities in the different ways (the changes include decrease or increase in population size or change in the distribution of populations)
What are examples of abiotic factors which effect communities?
ENVIRONMENTAL CONDITIONS-light intensity, moisture level, soil pH
TOXIC CHEMICALS-pesticides can build up in food chains through bioaccumulation, excess fertilisers can cause eutrophication in lakes and ponds leading to death of organisms
Define bioaccumulation:
bioaccumulation- at each level of the food chain the concentration of pesticides increases, so organisms at the top receive a fatal dose
What are examples of biotic factors which affect communities?
AVAILABILITY OF FOOD
NUMBER OF PREDATORS
COMPETITION-organisms compete with other species(and members of their own species) for resources (such as for plants: light, space, water, minerals;such as for animals: space, shelter, food, water, mates)
Describe a practical of how to use a Quadrat to study the population size of small organisms:
To compare the population size of an organism in two sample areas:
- place a quadrat on the ground at a random point within your first sample area, this will help to make sure the results you get are representative of the whole sample area
- count all the organisms you’re interested in within the quadrat
- repeat and work out the mean number of organisms per quadrat within the sample area
- repeat all the steps above for the second sample area
- finally compare the two means
What is a quadrat?
A quadrat is a square frame enclosing a known area (e.g. 1m)
How do you estimate population size by scaling up from a small sample area?
You need to work out the mean number of organisms per 1m^2
Then you just multiply the mean by the total area of the habitat
What do food chains show?
Food chains show what is eaten by what in an ecosystem.
What are the levels of a food chain?
Producer: make their own food using energy from the sun
Primary consumers: eat producers
Secondary consumers: eat primary consumers
Tertiary consumers: eat secondary consumers
Decomposes: all organisms eventually die and get decomposed by decomposers, decomposers break down dead material and waste
What is each level in a food chain called?
Tropic level
Describe a pyramid of numbers:
Each bar on the pyramid shows the number of organisms at each stage of the food chain
- the size of the bar is determined by the number of organisms on that trophic level
- the bottom layer of the pyramid is the producers then the next layer up is the primary consumers and so on
- it’s not always a uniform pyramid however
Describe a pyramid of biomass:
- each bar shows the mass of living material at that stage of the food chain
- biomass pyramids are practically always the right shape for a pyramid
What are pyramids of energy transfer?
Pyramids of energy transfer show the energy transferred to each trophic level in a food chain
-pyramids of energy are always the right shape, a regular pyramid
What is transferred along a food chain?
Energy is transferred along a food chain.
What are the stages along a food chain?
What are the stages called?
Producer Primary consumer Secondary consumer ... Decomposers
Stages called: trophic levels
Describe a general food chain:
- plants use energy from the sun to photosynthesise
- not all the energy the energy from one trophic level is passed onto the next (about 90% is lost)
- only around 10% of the total energy available becomes biomass(stored or used for growth)
- this is the energy that’s transferred from one trophic level to the next
Where does almost all energy for living things come from?
Energy from the sun is the source of nearly all life on earth
How is energy lost in a food chain?
- some parts of food (roots, bones) aren’t eaten by organisms so the energy isn’t taken in, some parts of food are indigestible(fibre) and come out as waste
- used for staying alive (respiration)
- energy is eventually transferred to the surrounding as heat
Define food web:
Food webs show how food chains are linked
-all species in a food web are interdependent, which means if one species changes it affects all the others
In an ecosystem what is constantly happening to the materials?
Materials are constantly being recycled in an ecosystem
-carbon and nitrogen are recycled through both abiotic and biotic components of an ecosystem
What does the carbon cycle show?
The carbon cycle shows how carbon is recycled.
- carbon is an element in the material that all living things are made from
- there’s only a fixed amount of carbon in the world, this means it’s constantly recycled
What is the only way carbon is removed from the air in the carbon cycle?
Photosynthesis
-green plants use carbon from carbon dioxide in the air to make carbohydrates, proteins and lipids
How does carbon get from plants to animals?
Eating
-animals eat the plants which passes on the carbon compounds
How is carbon dioxide released back into the atmosphere by living things?
Respiration
-plants and animals both respire and release carbon dioxide back into the air
How is carbon released from plant and animals when they die?
Plants and animals eventually die and decompose
-the are decomposed by decomposers (e.g. bacteria and fungi) into useful of carbon compounds
How do decomposers break down dead material?
Decomposers release enzymes, which catalyse the breakdown of dead material into smaller molecules. Decomposers release carbon dioxide back into the air by respiration as they break down the material.
How is the carbon in fossil fuels returned back into the atmosphere as carbon dioxide?
Combustion (burned)
Some useful plant and animal products (e.g. wood and fossil fuels), are burned which releases carbon dioxide back into the atmosphere
Why is decomposition critical for balance in an ecosystem?
Decomposition of materials means that habitats can be maintained for the organisms to live there (e.g. nutrients are returned to the soil and waste material doesn’t just pile up)
How is carbon monoxide produced?
When fossil fuels are burnt without enough air supply they produce carbon monoxide
What are some facts about carbon monoxide?
- it’s a poisonous gas
- if it combines with haemoglobin in red blood cells, which is an irreversible reaction so oxygen is unable to bind with the haemoglobin
What is the main production of carbon monoxide?
Carbon monoxide is mainly produced in car emissions
-most modern cars are fitted with catalytic converters that turn carbon monoxide into carbon dioxide
What are types of air pollution?
Carbon monoxide
Sulphur dioxide
How does sulphur dioxide produce acid rain?
- burning fossil fuels releases harmful gases like carbon dioxide and sulphur dioxide
- sulphur dioxide comes from sulphur impurities in the fossil fuels
- when sulphur dioxide mixes with rain clouds it forms dilute sulphuric acid
- this then falls as acid rain
What are the main causes of sulphur dioxide production?
Internal combustion engines in cars and power stations are the main causes of acid rain
In what way is acid rain harmful to the environment?
Acid rain kills fish and trees
- acid rain can cause a lake to become more acidic, this has a severe effect on the lake’s ecosystem, many organisms are sensitive to changes in pH and can’t survive in more acidic conditions
- acid rain kills trees because the acid damages the leaves and releases toxic substances from the soil, making it hard for trees to take up nutrients
What is the greenhouse effect?
-gases in the earths atmosphere absorb most of the heat that would normally be radiated back out into space and re-radiate it in all directions this is called the greenhouse effect
What is the temperature of the earth determined by?
The temperature of the earth is a balance between the energy it gets from the sun and the energy it radiates back out into space
What are examples of green house gases?
Water vapour Carbon dioxide Methane Nitrous oxide CFCs
How are humans causing the enhanced greenhouse effect?
- human beings are increasing the levels of greenhouse gases in the atmosphere, especially carbon dioxide
- because of this the earth is heating up, global warming is a type of climate change, this climate change can cause: extreme weather, rising sea levels, polar ice caps melting
- all these effects can cause habitat loss, which could effect food webs and crop growth
Why do we need the greenhouse effect?
If this process didn’t happen, then the earth would get very cold, very quickly at night
How do humans produce carbon dioxide?
- car exhausts, industrial processes, burning fossil fuels
- deforestation for timber and to clear land for farming
How do humans produce methane?
- naturally produced in - rotting plants in marshland
- man made sources of methane - rice farming and cattle rearing
How do humans produce nitrous oxide?
- naturally - bacteria in soils and in the ocean
- human activity- fertilisers, vehicle engines and industry
How do humans produce CFCs?
- CFCs are man-made chemicals that were once used in aerosol sprays and fridges
- most countries have agreed not to produce them anymore because of the effect on the ozone layer
- but some CFCs still remain and get released (e.g. Leaks from old fridges)
What problems can fertilisers cause?
Fertilisers can cause eutrophication
How can fertilisers cause eutrophication?
- fertilisers cause big problems when they end up in lakes and rivers
- nitrates and phosphates are put onto fields as mineral fertilisers
- if too much fertiliser is applied and it rains afterwards, it can be leached into rivers and lakes
- this cause eutrophication
What is eutrophication?
- the extra nutrients cause algae to grow fast and block out the light
- plants on the water bed can’t photosynthesise due to lack of light and die
- microorganisms that feed on the dead plants retire and deplete all the oxygen in the water
- organisms that need the oxygen such as fish die
What are the two ways eutrophication can be caused?
FERTILISERS
SEWAGE POLLUTION - sewage contains lots of phosphates from detergents, it also contains nitrates from urine and faeces
What are positives from deforestation?
- build their own houses or grow crops to feed their families.
- This is often by large companies who deforest to provide land for cattle, rice fields and growing crops for biofuels.
- It creates jobs
