Define the term population.
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Define the term population.
A population is a group of organisms of the same species living in the same place at the same time.
Define the term community.
A community includes all of the populations living in the same area at the same time.
True or False?
A habitat is the place that an organism lives.
True.
The place where an organism lives is its habitat, e.g. a meadow or a woodland.
True or False?
Living organisms only interact with the living components of their environment.
False.
Living organisms interact with both the living components (each other) and the non-living components (e.g. the temperature and rainfall) of their environment.
Define the term ecosystem.
An ecosystem is all of the organisms that live in an area, and their interactions with the living (biotic) and non-living (abiotic) factors in their environment.
True or False?
Animals within a community often compete with each other for light, space, water and minerals.
False.
It is plants that compete for light, space, water and minerals.
Animals compete for food, mates and territory.
In the context of ecosystems, what is interdependence?
Interdependence refers to the fact that organisms living in the same habitat depend on each other. A change in one species will affect other species.
When is a community considered stable?
A community is considered stable when the living and non-living components of the ecosystem are balanced; this results in population sizes that remain constant.
Define the term abiotic factor.
Abiotic factors are the non-living factors that influence ecosystems, e.g. temperature, sunlight, pH, salinity, precipitation.
What are some examples of abiotic factors?
Examples of abiotic factors include:
Light intensity
Temperature
Water availability
Soil pH / moisture / mineral content
Wind speed
Carbon dioxide concentration
Water pH
Oxygen concentration
How might a decrease in water availability affect a population of living organisms?
A decrease in water availability might affect a population of living organisms as follows:
The population size might decrease
The population might change its distribution by leaving one area for another in search of more water
True or False?
An increase in temperature from 20 °C to 30 °C would result in an increased population size for a plant species.
True.
An increase in temperature from 20-30 °C will increase the rate of photosynthesis in plants, so it is likely that the plants will grow faster and the population size will increase.
True or False?
Competition is an abiotic factor.
False.
Competition is a biotic factor as it is a living factor that affect organisms in an ecosystem.
Define the term biotic factor.
Biotic factors are the living factors that affect organisms in an ecosystem, such as competition, predation and disease.
Give examples of biotic factors that could affect populations.
Biotic factors that could affect populations include:
Predators
Competition
Availability of food organisms
Pathogens /disease
True or False?
An increase in the size of a prey population is likely to cause a decrease in the size of a predator population.
False.
A decrease in the size of a prey population will most likely result in a decrease in the size of a predator population. This is because there will not be enough food so predators will die, or leave.
Competition is a biotic factor. Define the term competition in this context.
Competition occurs when organisms fight for the same resources, e.g. food or mates
True or False?
Populations that compete for the same resources are likely to be smaller than equivalent populations that are not experiencing competition.
True.
Competition is likely to reduce the size of a competing population. In extreme cases a less well-adapted population may die out.
Define the term adaptation.
An adaptation is a feature that improves an animal's ability to survive in its natural environment.
Give examples of structural adaptations in desert plants.
A desert plant may have the following structural adaptations:
spines instead of leaves to reduce surface area and therefore water loss
a succulent stem to store water
deep tap roots to obtain water from the water table deep underground
shallow surface roots to collect water from dew or rainfall
True or False?
Large ears in elephants is an example of a functional adaptation.
False.
Large ears is a structural adaptation.
Functional adaptations are physiological or biochemical and so would include features such as sweating or shivering in thermoregulation.
Give an example of a behavioural adaptation.
A behavioural adaptation is any behaviour which increases the chances of survival, e.g.
staying in a cool burrow during the heat of the day and hunting for food at night
digging burrows for nesting and to protect young
huddling together to share body heat in cold conditions
True or False?
Small ears on an arctic fox are a structural adaptation to minimise heat loss.
True.
Small ears in arctic foxes are a structural adaptation to minimise heat loss as they provide a smaller surface area to volume ratio compared to larger ears.
Define the term extremophile.
An extremophile is an organism which lives in an extreme environment, e.g.
very high or low temperatures
very high pressures
very high salt concentrations