Topic 9: Ecosystems Flashcards
What do organisms need to stay alive?
They need resources. Plants need space to get light, water, carbon-dioxide, oxygen, warmth and mineral ions.
Animals need oxygen, food and water. They also need somewhere to shelter from the weather or avoid predation from other animals. This means that organisms are continually interacting with each other and their environments.
What is an ecosystem?
An area in which all the living organisms and all the non-living physical factors from a stable relationship that needs no input from outside the area to remain stable.
What is a community?
All the organisms that live and interact in an ecosystem form a community.
What is a population?
A group of one species living in the same area.
What does interdependent mean in terms of species?
When species are dependant on each other for resources that are dependant on each other for resources.
What is a habitat?
Where populations live within an ecosystem. A habitat includes the other organisms that affect the populations and local environment.
Define the term abundance:
A measure of how common something is an area, such as its population size.
What is a quadrat?
A square frame of known area, such as 1m sq, that is placed on the ground to get a sample of the organisms living in a small area.
Why do we use quadrats?
Because it is impossible to measure population size by counting all the organisms in an area. Quadrats give an estimate.
How do we use quadrats?
They are placed randomly in an area, and the number of individuals in each quadrat is counted.
What is the equation to estimate population size?
Population size = number of organisms in all quadrats x total size of area where organism live/total area of quadrats
What is a food web?
This shows the feeding relationships between the organisms in a community.
Why do we use food webs?
We use them to help predict what will happen if there are changes in the ecosystem.
What are the different categories of a food web?
Predators/tertiary consumers: Eat secondary consumers and sometimes primary consumers. They eat thing below them in the food chains and are carnivores/omnivores.
Primary consumers: the first trophic level of consumers. Primary consumers are herbivores. Herbivores eat plants but not other animals.
Secondary consumers: carnivores that eat primary consumers/herbivores.
What is the difference between abiotic and biotic factors?
Abiotic: Non-living conditions that can influence where plants or animals e.g temperature, light intensity.
Biotic: living components (the organisms) in an ecosystem.
Where is sunlight energy transferred to and how does this affect abiotic and biotic factors?
A lot of the suns energy is transferred to substances in new plant biomass (the mass of tissue). The rest is transferred it the environment by heating, during processes such as respiration.
Other organisms cannot make use of this energy transferred to the environment from the sun by heating so these energy transfers are less useful.
Define the term biomass:
The total mass in living organisms, usually shown as the mass after drying.
What is biodiversity?
The variety of species in an area.
What is meant by trophic levels?
Feeding levels in a food chain, such as, produces, primary consumer, secondary consumer, predator.
What happens to the energy when a primary consumer (herbivore) eats a produces and when a secondary consumer eats a primary consumer?
The energy stores in the plants biomass is transferred to the herbivore when it eats it. The energy stored in the primary consumer is then transferred to the carnivore/secondary consumer that eats it.
During a food web why might not all the energy transferred from e.g the plant to the herbivore be transferred to the carnivore that’s eats the herbivore?
- when the herbivore eats the producer some of the energy is transferred from the herbivore to the surroundings by heating during metabolic processes, e.g respiration.
- some energy is stores in the herbivores waste/urine, which is not able to the predator to eat.
- the predator may not be able to eat all of the herbivore e.g eyes (etc)
What is a sankey diagram?
This shows energy transfers, where the width of each arrow is proportional to the amount of energy is represents.
What equation can you use to work out the efficiency of an energy transfer?
Energy transferred to biomass/total energy supplied to organism
To get it as a % multiply by 100.
Usually the numbers are between 0-1. 1 being 100% efficient.
What is a pyramid of biomass?
When all the biomass organisms is measured at each trophic level in an ecosystem, they can be displayed as a pyramid of biomass.
(Diagram showing the amount of biomass at different trophic levels in a food chain)
How can we interpret a pyramid of biomass?
The diagram usually has a pyramid shape because energy is transferred from the food chain to the environment at each Tropic level. With less energy available less biomass can be produced.
Why is the pyramid of biomass useful?
It helps explain why there is a limit in a food chain. Eventually the energy becomes too little to support animals higher up the food chain.
What is meant by the distribution of organisms?
Where organisms are found in an ecosystem.
How can the distribution of organisms be affected?
Physical and chemical factors, such as temperature, rainfall and substances in the soil.
How can the abiotic factors on the distribution of organisms in an ecosystem be measured?
Using a belt transect. Quadrats are places along a line in an habitat and the abundance of organisms are measured as well as the abiotic factors in each quadrat position. Changes in abundance can show which abiotic factors has the greatest affect on the organism.
Define the term adaptation:
The features of something that enable it to do a certain sanction or job.
How could droughts or flood cause species to die?
Few organisms can survive a drought for long. Most land plants cannot survive if their roots are under water for too long. Of the climate change results in more flooding or more drought, then many species in different communities may die out.
How can temperature affect the distribution of organisms?
All organism adaptations that make them suited to life at particular temperatures. A long-term rise or fall in temperature in an eco-system will change the distribution of some organisms and so affects the whole community.
Why do most algae live within 30m of the oceans surface?
They need light to photosynthesise in order to survive. Most algae can get enough light sighing 30m of the surface. However, on land light is limited in forests, which is why that only few plants grow on the forests floor due to the dense trees and forest above it.
What are pollutants?
Substances that cause harm in the environment.
What is the effect of pollution and what causes pollution?
Human activity causes pollution as they release pollutants. These can poison organisms or chase harm to organisms in other ways (such as plastics being eaten by fish and other organisms)
Why is energy lost in a food chain?
- Not all the organism is eaten.
- life processes of the organism that is being eaten requires energy (e.f for respiration). This energy is lost.
- energy used up by organism for processes like temperature regulation.
- the organism will have used energy through movement.
- some energy is lost through the excretion of waste materials.
Core practical: Quadrats and Transects
How can you study and measure the affects of abiotic factors(sunlight intensity) on an abundance of plants using a belt transect?
1) peg out a long tale measure (at least 20m) on the ground, starting were there is no shade and ending in heavy shade. This is the transects line.
2) make measurements along regular intervals along transect of how many daisies there are. (your intervals may depend on how long the transect line is and the time you have to record information.)
3) place the top left hand corner of the quadrant at a measurement point on the transect line.
4) measure the abiotic factors at that point and record them.
5) Record the abundance of your selected plants in the quadrat.
6) Repeat steps C-E at each measurement point along transect.
What are the dependant and independent variables for the Quadrat and Transect practical?
Independent- amount of sunlight.
Dependant- how many daisies in each quadrat.
What are 2 abiotic factors linked to climate?
- temperature
- rainfall
What does predation mean?
When one animal species kills and eats another animal species.
What is meant by completion between organisms?
When organisms need the same resources as each other to survive, they struggle against each other to get those resources. We say that they ‘compete’ for those things.
What is the predator-prey cycle?
The regular variation in numbers of predators and numbers of prey within a feeding relationship.
What is an indicator species?
Organisms that are sensitive to polluting chemicals e.g lichen. They can indicate how much pollution there is in an area by how many of these organisms can be found.
What are lichen?
Lichen grow on trees. Lichens have a mutualistic relationship between a fungus and an alga. They cannot grow well in places with high pollution (e.g near factories or cities) so are only found in places with low pollution.
