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Habitat
The place where an organism lives
Population
All the organisms of one species in a habitat
Community
All the different species in a habitat
Ecosystem
All the organisms living in a particular area and all the non-living conditions
Abiotic factors
Environmental factors that are not living
Abiotic factor examples
Light intensity
Humidity
Temperature
Pollution
Air quality
Climate change
Biotic factors
Relating or as a result of living organisms
Biotic factor examples
Introduction of species
Parasites and diseases
Removal of predators
Competition between organisms
Availability of food
Quadrats
A square frame enclosing in a known area
How to use quadrats to compare population size of an organism in two sample areas
Place the quadrat on the ground at a random point in the first sample area, it can be done by dividing the sample area into girds and using a random number generator to pick the coordinate where the quadrat will go to, this makes results representative
Count all organisms that you are studying that are inside the quadrat
Repeat step 1 and 2 multiple times
Work out the mean number of organisms per quadrat within the first sample area
Repeat steps 1-4 in the second sample area
Compare the two means
Mean formula
Total number of organisms/Number of quadrats placed
Estimating population size from a small sample area
Find the mean number of organisms per metre squared
Multiply this number by the total area in metre squared of the habitat
Pyramids of numbers
They show the number of organisms at the stage of the food chain
The more organisms there are, the longer the bar
Normally as you go up trophic levels, the number of organisms goes down as it takes a lot of food from the level below to keep one animal alive
It will not always look like a pyramid
Pyramids of biomass
Each bar shows the mass of living material at that stage of the food chain
How much all the organisms at each level would weigh if you put them all together
It will always have the right shape
Pyramids of energy transfer
Shows the energy transferred to each trophic level in a food chain
Always the right shape, a regular pyramid
Where is energy sourced from?
The Sun, it provides energy for nearly all life on Earth
What plants use sunlight for
Plants use sunlight to make food during photosynthesis and the energy will continue to go around the food chain as animals eat plants and each other
Energy transfer between trophic levels
Not all energy is able to pass to the next trophic level, around 90% is lost in various ways
Most of this energy is eventually transferred to the surroundings by heat
Only around 10% of the total energy available becomes biomass for storage or growth
This is the energy that gets transferred from one trophic level to the next
Energy that does get taken in is for staying alive, like respiration
Indigestible parts
Some parts of food like roots or bones don’t get eaten so energy there isn’t taken in, some parts are indigestible so they come out as waste
Sulphur dioxide
Released from burning fossil fuels and when dissolved in rain water, it creates sulphuric acid that forms acid rain
Acid rain
Kills trees and damages leaves, releasing toxic substances from the soil that stops minerals from being absorbed
This also acidifies the water in lakes which kills many plants and animals sensitive to pH
Carbon Monoxide CO
Happens during incomplete combustion
CO binds with haemoglobin so it cannot transport oxygen which slowly kills your body
Comes from car emissions
Greenhouse gases
Water vapour
Carbon dioxide
Methane
Chlorofluorocarbons (CFC)
Nitrous oxide
Greenhouse gas
Traps energy from the Sun in the atmosphere, without them, we would get very cold without any heat
Human activity on global warming
Human activity on global warming
Increasing the amount of carbon dioxide, CFC’s and nitrous oxide
This causes rising sea levels, habitat loss and extreme weather
Autotrophs
Organisms that can produce their own food or can self-feed
Heterotrophs
Organisms that eat other things to obtain energy and protein