Habitats and Ecosystems Flashcards
What does habitat mean?
A place where an organism lives.
What does population mean?
All the organisms of the same species living in a habitat.
What does community mean?
The populations of different species living in a habitat.
What does abiotic factors mean?
Factors that affect a habitat that aren’t living.
What does biotic factors mean?
Factors that affect a habitat that are living.
What does ecosystem mean?
The interaction between a community of living organisms and their environment.
Why do the organisms in an ecosystem interact with each other?
There is competition for food, light, mates, mineral ions, etc.
What is interdependence?
When an organism relies on another, e.g. pollination and seed dispersal.
What does it mean for an ecosystem if it is biodiverse?
It has many species and means the community and ecosystem is stable and populations don’t fluctuate.
What is the benefit of a stable ecosystem?
It is more resistant to human activity and environmental change.
How do we represent feeding relationships within a community?
Using a food chain, each part of the food chain is called a trophic level.
What is trophic level one?
A producer (usually green plants or algae) makes glucose via photosynthesis.
What is trophic level two?
Herbivores which eat plants and algae, primary consumer.
What is trophic level three?
Carnivores which eat herbivores, secondary consumers.
What is trophic level four?
Carnivores which eat other carnivores, tertiary consumers.
What is a predator?
Animals that eat other animals.
What is a prey?
Animals that get eaten by other animals.
What is an apex predator?
A predator that has no other predators.
What happens to the level of predators and prey in a healthy stable community?
It follows a cycle of negative feedback.
What is a ‘predator-prey cycle’?
The prey population increases due to more food and less predators. The predator population begins to increase as there is more food. There is a delay however as it takes time for the predators to catch prey and then begin reproducing.
Because the predator population has increased more prey are hunted causing the prey population to decrease.
After a time predator population decreases as there is fewer prey to hunt and therefore more competition.
The cycle repeats.
What is biomass?
Biomass is the mass of living material.
How do we represent biomass in a food chain?
Pyramids are used to represent relative amount of biomass in each level of the food chain, the producers are always at the bottom.
What is important to remember about biomass pyramids?
Label each trophic level and label the x axis with units.
What happens to biomass through a food chain?
Biomass is lost at each trophic level, approximately 10% of biomass is passed up into the next trophic level.
Why is biomass lost?
-Not all of the organism is edible or is eaten by other animals.
-Some absorbed material is egested as faeces.
-Some absorbed material is lost as waste e.g. carbon dioxide and water from respiration and urea.
-Used for respiration.
How do we equate biomass lost?
Biomass in previous trophic level - Biomass in current trophic level
How do we equate efficiency of transfer?
(Biomass in higher trophic level/Biomass in lower trophic level) * 100
What is a transect?
A method of sampling used to measure the distribution of a species over a distance / across or along a habitat.
Why do we do transects?
To evaluate whether an environmental factor may be affecting the distribution of a species along the transect.
What different environmental factors can be measured when taking a transect?
-Light Intensity using a light meter
-Soil pH using an indicator
-Temperature using a thermometer
-Width of leaves using a ruler
How do we carry out a transect?
1- Layout a tape measure across a desired area
2- Place a quadrat down continuously along the tape measure or at every other metre
3- Count and identify the species in the quadrat (use a key)
4- Use a meter to measure an abiotic factor at the same time if investigating how that factor affects species distribution (always measure at same height/direction)
5- Then repeat by completing another transect further along the habitat.
6- Repeat at different times of the day/season/year
