Organisms and enviroment Flashcards
(42 cards)
What is the main source of energy in biological systems?
The sun
Decribe the flow of energy in biological systems.
- Light energy from the sun is trapped by photosynthetic organisms
- Energy is then stored as chemical energy.
- Energy is eventually lost to the enviroment
What is a food chain?
A way of showing the flow of energy between organisms starting with the producer.
How is energy transferred between organisms in the food chain?
By ingestion ( organisms eating other organisms ).
What is a trophic level?
The position that an organism hold in the food chain, food web, pyramid of number or pyramid of biomass.
Why are biomass transfers not 100% efficient?
Energy is lost through:
- Egestion (removal of faeces)
- Excretion (removal of waste products e.g urine)
- Respiration
- The production of inedible bones and shells
Why do food chains have fewer than 5 trophic levels?
Biomass transfers are not 100% efficient and so there is not enough energy to support 5 trophic levels.
Why is it most efficient to supply plants as food for humans?
- Using plants as food for livestock waste energy as the biomass transfers are not 100% efficient
- Eating plant transfers can maximise the amount of energy gained as there is only one transfer.
What is a food web?
Multiple interconnected food chains.
What is a producer?
An organism that makes its own food (usually through photosynthesis)
What is a consumer?
An organism that gets energy by eating other organisms.
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 are herbivores?
Animals that only eat plants.
What are carnivores?
Organisms that mainly eat animals.
What are decomposers?
Organisms that break down dead matter.
Explain the impact humans have on food chains and webs by overharvesting certain species?
Many organisms rely on other organisms for food, overharvesting can reduce the amount of food available for other animals.
Explain the impact humans have on food chains and webs by introducing other species into a habitat.
Introducing new organisms increases competition and can interfere with the food chain, causing organism who cannot compete to die.
Explain the impact humans have on food chains and webs by introducing other species into a habitat.
Introducing new organisms increases competition and can interfere with the food chain, causing organism who cannot compete to die.
What is the pyramid of numbers?
A pyramid of numbers shows the number of organisms at each trophic level.
What is a biomass pyramid?
A pyramid that shows a total dry mass of organisms at each trophic level
Why is the pyramid of biomass a better way of representing a food chain than a pyramid of numbers?
Pyramids of biomass take into account the size of the organisms and are less easily misinterpreted.
Describe the carbon cycle.
- Plants fix carbon dioxide into carbon molecules during photosynthesis
- The organic carbon-containing molecules are passed down onto organisms that eat plants
- Carbon dioxide is released back into the atmosphere by respiration from animals and plants
- Burning fossil fuels also release carbon dioxide into the atmosphere.
