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