8 - Ecology and the Environment Flashcards
What is a habitat?
The place where an organism lives
What is a population?
All the organisms of one species in a habitat
What is a community?
All of the different species in a habitat
What is an ecosystem?
All the organisms living in one particular area and all the non-living (abiotic) conditions
Describe how to estimate the population size using a quadrat
- Place a 1m2 quadrat on the ground at a random point within the area you’re investigating
- Count all the organisms in the quadrat
- Multiply by the total area of the habitat
- Repeat on another area to compare the population sizes
- The sample may not be a representation of the population
- The sample size affects the accuracy of the estimate (the bigger the sample the more accurate)
Describe how investigate the distribution of organisms using a quadrat
- Mark out a ling in the area you want to study
- Collect data along all points of the line using quadrats placed next to each other
What do food chains show?
-What has been eaten by what in the food chain
What is a producer?
The first organism in the food chain who makes their own food using energy from the sun
What are consumers?
Organisms that eat other organisms 1 - primary 2 - secondary 3 - tertiary Each stage is called a trophic level The arrow always points to what is eating it
Pyramids of numbers
- Each bar represents the number of organisms at that stage in the food chain
- Does not have to be a pyramid shape
Pyramids of biomass
- Each bar represents the mass of living material at that stage of the food chain (how much they weigh if all put together)
- Almost always a pyramid shape
- e.g. one fox weighs more than 100 flees
Pyramids of energy transfers
- Show the amount of energy transferred at each trophic level
- Always the right shape
How is energy transferred?
Along a food chain
- Energy from the sun is the source of energy for nearly all life on Earth
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How is energy transferred?
Along a food chain
- Energy from the sun is the source of energy for nearly all life on Earth
- Plants get energy from the sun from photosynthesis
- If a rabbit eats the plant not all of the energy will be transferred as it will be lost as heat
- The amount of original energy from the sun is transferred less and less as you travel up the trophic levels
What do food webs show?
How food chains are linked
The arrows point to the what eats the organism
Describe the water cycle
- Heat from the sun makes water evaporate from the land and sea turning it into water vapour (also evaporates from plants through transpiration)
- Warm water vapour is carried upwards and as it rises it cools and condenses to form clouds
- Water falls from the clouds as precipitation and is returned to the land and sea
- It is an endless cycle
Describe the carbon cycle
- The whole cycle is powered by photosynthesis
- Green pants use the carbon from CO2 to make carbohydrates, fats and proteins
- Eating passes the carbon compounds in the plant along to animals in a food chain or web
- Both plant and animal respiration releases CO2 back into the environment
- Dead plants and animals decompose
Describe the carbon cycle
- The whole cycle is powered by photosynthesis
- Green pants use the carbon from CO2 to make carbohydrates, fats and proteins
- Eating passes the carbon compounds in the plant along to animals in a food chain or web
- Both plant and animal respiration releases CO2 back into the environment
- Dead plants and animals are decomposed by bacteria and fungi which releases CO2 back into the environment by respiration
- Some useful plant and animal products (e.g. wood and fossil fuels) are burned (combustion) which releases CO2 back into the environment
- There is a fixed amount of carbon in the world meaning it is all recycled
How much nitrogen is in the atmosphere?
78% nitrogen gas which is very unreactive so cannot be used directly by plants and animals
Why is nitrogen needed?
For making proteins for growth
How to plants get nitrogen?
From the soil
What is nitrogen fixation?
Nitrogen fixation is the process of turning N2 from the air into nitrogen compounds in the soil which plants can use
Describe the process of nitrogen fixation
Lightning - the energy from the lightning bolt makes nitrogen react with oxygen in the air to give nitrates
Nitrogen-fixing bacteria - in roots (nodules )and soil
What bacteria is involved in nitrogen fixation?
Decomposers - break down proteins (in dead animals and plants) and urea (in animal waste) and turn them into ammonia
Nitrifying bacteria - turn ammonia in decaying matter into nitrates
Nitrogen-fixing bacteria - turn atmospheric N2 into nitrogen compounds that plants can use
Denitrifying bacteria - turn nitrates back into N2 gas. This is not beneficial to living organisms
How is carbon monoxide poisonous?
- When fossil fuels are burnt without enough air supply they produce carbon monoxide gas
- If CO combines with red blood cells it prevents them from carrying oxygen
- CO is mostly released in car emissions
- Most modern cars have a catalytic converter that turn CO into CO2 which is less dangerous
How is acid rain produced?
- By sulphur dioxide
- Burning fossil fuels released CO2 and SO2
- Sulfur dioxide
How is acid rain produced?
- By sulphur dioxide
- Burning fossil fuels released CO2 and SO2
- Sulphur dioxide comes from sulphur impurities in the fossil fuels
- When this gas mixes with rain clouds it forms dilute sulphuric acid
- This falls as acid rain
- Internal combustion engines in cars and power stations are the main causes of acid rain
How does acid rain kill fish and trees?
- Acid rain causes a lake to become more acidic which kills sensitive organisms and destroys ecosystems
- Acid rain can kill trains as it damages leaves and releases toxic substances from the soil making it hard for the trees to take up nutrients
What are greenhouse gases?
Gases that trap in heat energy from the sun and increase the overall temperature of Earth
These gases include water vapour, carbon dioxide and methane
What are greenhouse gases?
Gases that trap in heat energy from the sun and increase the overall temperature of Earth
These gases include water vapour, carbon dioxide and methane
What is adding to the greenhouse effect?
- Carbon dioxide
- Methane
- Nitrous oxide
- CFCs
How does carbon dioxide add to the greenhouse effect?
- Humans release CO2 in the atmosphere in car exhausts, industrial processes and burning fossil fuels
- Cutting down forests increases the amount of CO2 as there are less trees using it in photosynthesis
How does methane add to the greenhouse effect?
- Methane gas is produced naturally from rotting plants in marshland
- Manmade sources of methane include rice growing and cattle rearing
How does nitrous oxide add to the greenhouse effect?
- Nitrous oxide is released naturally by bacteria in soils and the ocean
- A lot more is released from soils after fertiliser is used
- Also released from vehicle engines and industry
How do CFCs add to the greenhouse effect?
- Manmade chemicals that were once used in aerosol sprays and fridges
- Not produced as much anymore as they damage the ozone layer
- Leaks from old fridges release CFCs
How do CFCs add to the greenhouse effect?
- Manmade chemicals that were once used in aerosol sprays and fridges
- Not produced as much anymore as they damage the ozone layer
- Leaks from old fridges release CFCs
Describe eutrophication
- Fertilisers enter the water after raining, adding extra nutrients (e.g. nitrates and phosphates)
- The extra nutrients cause algae to grow fast and block out light
- Plants can’t photosynthesise due to lack of light and start to die
- With more food available microorganisms that feed on dead plants increase in number and deplete (use up) all the oxygen in the water
- Organisms (e.g. fish) die
How can eutrophication be caused?
- Using too much fertiliser that enters lakes through rain
- Pollution by sewage as it contains lots of phosphates from detergents (e.g. washing powder) and also contains nitrates from urine and faeces
How does deforestation affect leaching?
- Trees take up nutrients from the soil before they can be washed away
- No trees mean nutrients get washed away and not replaced leaving infertile soil
How does deforestation affect soil erosion?
- Tree roots hold soil together
- When trees are removed soil can be washed away by the rain leaving infertile ground
How does deforestation affect the water cycle?
- Trees stop rainwater reaching rivers too quickly
- When they’re cut down rainwater can run straight into rivers which leads to flooding
- Transpiration from trees releases some of the rainwater back into the atmosphere
- When they’re cut down the overall climate can become drier
How does deforestation affect the levels of oxygen and carbon dioxide?
- Forests take up CO2 by photosynthesis and release it slowly when they decompose
- When trees are cut down and burnt the stored carbon is released
- Fewer trees means less photosynthesis which releases less oxygen and causes levels to drop
