Organisms and enviroment Flashcards
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.
State the effect of burning fossil fuels on carbon dioxide concentration inthe enviroment.
It releases more CO2 into the atmosphere and therefore increases the concentration of carbon dioxide.
State the effects of deforestation on carbon dioxide concentration in the enviroment.
- Trees take in CO2 during photosynthesis(decreasing the atmospheric carbon dioxide concentration)
- Cutting down trees will prevent this and so the atmospheric carbon dioxide concentration does not decrease.
Describe the water cycle
- Water from lakes and oceans evaporate
- 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 the rivers and oceans through surface runoff
Describe the water cycle
- Water from lakes and oceans evaporate
- 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 the rivers and oceans through surface runoff
Why is the water cycle important?
Living organisms needs water. The water cycle provides organisms on land a continous supply of water.
How is nitrogen cycled through the ecosystem? (brief)
- Nitrogen is fixed by lightning and bacteria
- Decomposers break down dead matter into ammonium ions
- Nitrifying bacteria ammonia turns into nitrites turns into nitrates
- Plants absorb nitrate ions
- Denitrifying bacteria releases nitrogen back into the atmosphere
What is deamination?
The removal of amine group in a amino acid.
What is deamination?
The removal of amine group in a amino acid.
State 4 roles of bacteria in the nitrogen cycle.
- Decomposition
- Nitrification
- Denitrification
- Nitrogen fixation
Define population?
A species that occupy the same habitat at the same time.
Define community.
All the different populations in the ecosystem.
Define ecosystem.
Both the community and their physical enviroment.
State 3 factors that affect population growth rates.
- Disease
- Predation
- Availability of food
Describe the lag phase in population growth.
The organisms are adjusting to the enviroment.
Key: Lag can also mean the lag on computer, the computer is adjusting to the internet
Describe the log phase in population growth.
The growth of the population is increasing at a fast exponential rate.
Describe the stationary phase of population growth.
The amount of births and deaths are equal.
Describe the death phase of population growth with limited resources.
Once the resources have been used up. The population begins to compete for resources and organisms will die as soon as resources become scarce.
State 4 implications of a rapidly increasing population size.
- More land needed for living
- Greater demands for health care
- Greater demands for education
- More resources needed which puts pressure on the enviroment
