7.2 Organisation of ecosystems (Combined) Flashcards
Define population
A species that occupy the same habitat
Define habitat
The place in which an organism lives
Define community
Populations of different species interacting
Define ecosystem
The interactions between the biotic and abiotic factors in an area
What do food chains show?
Food chains show the feeding relationships of different organisms and the flow of energy between the organisms
Define biomass
The total mass of living material
What are trophic levels?
The stages in a food chain
What do arrows in a food chain represent?
The direction of biomass transfer
Describe a simple food chain
● Producer
● Primary consumer
● Secondary consumer
● Tertiary consumer
What is a producer?
An organism that makes its own food
What types of organisms are producers?
Photosynthetic organisms like green plants and algae that trap energy from the Sun
What is a primary consumer?
An organism that feeds on producers
What is a secondary consumer?
An organism that feeds on primary consumers
What is a tertiary consumer?
An organism that feeds on secondary consumers
What is a predator?
A consumer that kills and eats other animals
What is prey?
An animal that is killed and eaten by another animal
Describe the pattern of predators and prey in a stable community
The numbers of predators and prey rise and fall in cycles
Why are producers the first trophic level?
● Producers provide all biomass for the food chain (production of glucose via photosynthesis)
● The rest of the food chain involves the transfer of the biomass
What piece of apparatus is used to measure the abundance and distribution of organisms in an area?
A quadrat
What piece of apparatus is used to study the distribution of organisms across a gradient?
Belt transect
When considering the abundance of organisms, what is meant by the term ‘mean’?
The average number of organisms
How is the arithmetic mean calculated?
Sum of each number of each organism / Total number of each type of organism
When considering the abundance of different organisms, what is meant by the term ‘mode’?
The most populous organism
When considering the abundance of organisms, what is meant by the term ‘median’?
The organism that represents the middle value when the numbers of each organism are arranged from lowest to highest
Describe how materials cycle through the living and non-living components of an ecosystem
- Organisms take in elements from the surroundings soil
- Elements converted to complex molecules which become biomass
- Elements transferred along food chains
- Elements return to the environment during excretion and decomposition of dead organisms
Give three molecules which are cycled through ecosystems
● Oxygen
● Carbon dioxide
● Water
Describe the carbon cycle
- Plants turn carbon dioxide into organic molecules during photosynthesis
- Organic carbon containing molecules are passed onto organisms that eat the plants
- Carbon dioxide is released back into the atmosphere by respiration from animals and plants
Burning fossil fuels also releases carbon dioxide into the atmosphere
Why is the carbon cycle important?
Carbon containing molecules such as glucose are important for living organisms to grow and provide energy for vital functions within cells
Describe the water cycle
- Water from lakes and oceans evaporates
- The evaporated water condenses into clouds and returns to earth as precipitation
- The water from precipitation is useful for life on land
- The water then returns to rivers and oceans through surface runoff
Why is the water cycle important?
Living organisms require water and the water cycle provides organisms on land with a continuous supply of water
Why are microorganisms important for the cycling of materials through an ecosystem?
Microorganisms (bacteria and fungi) return carbon to the environment by releasing carbon dioxide through respiration while they decompose dead matter.
The decomposition of dead matter in soil returns mineral ions to the environment for other organisms to use e.g. plants use mineral ions for growth
How can different temperatures be bad for certain communities.
If the temperature is too low, growth will be slower as organisms will use more energy to stay warm.
If the temperature is too high, organisms can die in water overcome limited as evaporation increases.
How can changes in water levels affect ecosystems? (Higher)
Animals may have to migrate to find water
Melting ice caps may destroy the habitats of some animals (either animals living in icy regions or by sea level rise)
How can atmospheric gases affect ecosystems? (Higher)
● Some organisms cannot survive when certain gases are present
● Polluted water can cause illness to animals that drink it
What detrimental impacts can sulfur dioxide have on the environment?
Formed when fossil fuels containing impurities are burnt
Sulfur dioxide can dissolve in water to form acid rain which can erode buildings and pollute water sources
What detrimental impacts can carbon monoxide have in the environment?
● Carbon monoxide is formed from the incomplete combustion of fossil fuels
● Carbon monoxide binds irreversibly to haemoglobin which prevents it from carrying oxygen
● Too much exposure can cause unconsciousness and death
Name five greenhouse gases
● Water vapor
● Carbon dioxide
● Nitrous oxide
● Methane
● CFCs
Give three human activities that contribute to greenhouse gases
● Burning fossil fuels
● Deforestation
● Large scale livestock farming
How do greenhouse gases lead to global warming?
● Greenhouse gases allow heat from the Sun to enter the atmosphere
● The gases act as a ‘blanket’ and trap the heat in the atmosphere
State three negative consequences of global warming
● Sea levels rise caused by melting ice icebergs
● Disrupted farming and agriculture
● Increased spread of diseases and warmer climates
