Unit 19 : Organisms and their Environment Flashcards
Define Food Chain
a chart showing the flow of energy (food) from one organism to the next, beginning with a producer
Define Food Web
showing a network of interconnected food chains
Define Producer
Define Consumer
an organism that gets its energy by feeding on other organisms
Define Herbivore
an animal that gets its energy by eating plants
Define Carnivore
an animal that gets its energy by eating other animals
Define Decomposer
an organism that gets its energy from dead or waste organic matter
Define Trophic Level
the position of an organism in a food chain, food web or ecological pyramid
Define Primary Consumer
eat vegetables
Define Secondary Consumer
eat meat/drink milk
Define Tertiary Consumer
eat a predatory fish, salmon
Why do food chains have no more then 5 Trophic levels?
most food chains usually have fewer than five trophic levels this is because of the 10% energy law which states that only 10% of the energy is passed on so, the larger the food chains get the lesser energy is available for animals at higher trophic levels.
What is the Energy Law?
in a food chain at each trophic level only 10% energy is passed on to the next trophic level and the remaining energy is lost as heat energy or undigested food and metabolic processes.
Why is a Vegetarian Diet more Energy Efficient?
a vegetarian diet is more energy efficient because it provides energy directly from the producer resulting in only 10% energy loss as compared to a livestock - based diet where the livestock would have to be fed a lot of crops to provide a similar amount of energy.
What is a Pyramid of Numbers?
pyramids of numbers show how many consumers there are in a given ecosystem as well as the number of producers at each trophic level. this starts with the highest number of producers who are on bottom and then in order from down to up; primary, secondary, tertiary, and quarterly
What is a Pyramid of Biomass
pyramids of biomass show how much mass there is at each trophic level. this starts with the highest number of producers who are on bottom and take up the most mass and then each subsequent consumer has less mass as there isn’t enough to feed them. the biomass is counted by the average mass of a species multiplied by the number of the species.
What is the Pyramid of Energy
pyramids of energy show how much energy there is at each trophic level. the sunlight is the energy that producers change into forms of sugar. then consumers take energy from producers and each other.
Define Carbon Cycle
describes how carbon moves between the atmosphere, soils, living creatures, the ocean and human sources
Define Bioaccumulation
the gradual gathering of substances traveling from the environment into an organism
Define Photosynthesis
a process in which plants use carbon and water to make food using the energy from sunlight
Define Fossil Fuels
a natural fuel formed millions of years ago from decaying organic matter
Define Atmosphere
a blanket of gases surrounding the earth
Explain the steps of the carbon cycle
- carbon that is present in the atmosphere gets absorbed by plants for photosynthesis
- plants containing carbon are consumed by animals and the carbon is bioaccumulated in their bodies
- the animals and plants die and while decomposing the carbon is released into the atmosphere
- carbon that isn’t released into the atmosphere is turned into fossil fuels which are used for man made activities.
Define Nitrogen Cycle
the nitrogen cycle is the process in which nitrogen is cycled through the environment, moving from the atmosphere to the soil, to living things, and back to the atmosphere
Define Nitrogen Fixation
nitrogen fixation is where nitrogen gas from the atmosphere is converted into nitrates by either bacteria found in soil, specific root nodules of legumes, or even when lightning strikes the ground
Define Nitrogen Assimilation
nitrogen assimilation occurs when the nitrates have been absorbed by the soil and are being used to create amino acids that plants benefit from. animals then eat the plants, causing nitrogen to transfer into protein in the animal. this can pass onto other animals when feeding.
Define Nitrogen Ammonification
nitrogen ammonification happens when decomposers convert the excretion and carcasses of animals into nitrogen. once returned to the soil, the nitrogen gets converted into ammonia
Define Nitrification
nitrification is when the ammonium ions in the soil are converted into nitrates by nitrifying bacteria
Define Denitrification
denitrification takes place when denitrifying bacteria in the soil converts nitrates back into nitrogen gas, repeating the cycle
Define Population
a group of organisms of one species living in the same area at the same time
Define Community
all of the populations of different species in an ecosystem
Define Ecosystem
a unit containing the community of organisms and their environment interacting together
Name and Explain 3 Factors that Affect the Rate of Population Growth
- food supply - having a good food supply in both quality and quantity can enable organisms to produce more offsprings successfully. shortages in food supply can lead to starvation causing death or forced emigration, reducing the population.
- predation - if there is large amounts of predation in a population, the rate of breeding may not be fast enough to sufficiently replace the organisms that have been eaten, causing the population to reduce.
- disease - diseases can easily spread and may end up resulting in an epidemic. epidemics reduce population sizes rapidly and if spread globally, could become a pandemic.
Define and Explain 4 Stages of the Sigmoid Curve of Population Growth
- lag phase - there is a low amount of mature and reproducing organisms and they may be widely distributed.
- log (exponential) phase -
all conditions are optimum and the growth rate has reached its maximum. exponential growth occurs as the limiting factors do not affect the growth much. - stationary phase - limiting factors begin to slow the growth more as the population has reached something known as the “carrying capacity” (maximum population size) of the environment. when the death rate and the birth rate become equal, the curve levels and fluctuates around the carrying capacity
- death phase - this is when the death rate becomes larger then the birth rate due to the factors which affect population growth like competition, lack of food, etc.