topic 13 - ecology and the environment Flashcards
what is a population
a group of organisms of the same species living in the same place at the same time
what is a community
A community includes all of the populations living in the same area at the same time
what is interdependence
when within a community, each species depends on others for food, shelter, etc. if one species is removed, it affects the whole community
what is a habitat
the place where an organism lives
what is an ecosystem
all the biotic factors and all the abiotic factors that interact within an area at one time
what are biotic factors
living components such as plants and animals
what are abiotic factors
non-living components such as light intensity, mineral ions, water availability
what are quadrats
square frames made of wood or wire. they are placed on the ground and the organisms within them are recorded
practical: investigating population size in two different areas using quadrats method
- use 2 tape measures to lay out a survey area e.g. 10m by 10m in your chosen habitat
- use a random number generator to create a set of coordinates to place your first quadrat to avoid bias
- count the number of chosen species that are found within the quadrat
- estimate the population of the species using the equation: (total surface area/area sampled) x total number of species counted
what is biodiversity
the range and variety of different species of organisms on Earth, or within an ecosystem
3 importances of biodiversity
- Different species depend on each other for:
- Food
- Shelter (eg. birds nesting in trees)
- Maintenance of the physical environment
- High biodiversity ensures the stability of ecosystems by reducing the dependence of one species on another for these three things
- Populations with high levels of diversity are also more likely to be resilient to sudden environmental impacts or disease
e.g.
If the mouse population was suddenly wiped out, the fox and the hawk populations might decrease but would not be wiped out as mice are not their only food source
This example ecosystem has sufficient biodiversity to support the fox and hawk populations
The fox population can still depend on the rabbit and frog populations for food
The hawk population can still depend on the frog and sparrow populations for food
practical: measuring biodiveristy measure
- use 2 tape measures to lay out first survey area
- use a random number generator to create a set of coordinates to avoid bias
- count the different numbers of species in the first quadrat
- repeat process until you have collected data for 10 quadrats
- repeat for the second survey area
- record data in a table for each survey area
- the survey area with the greatest number of different species has the greatest biodiversity
7 examples of abiotic factors
- light intensity
- temperature
- moisture levels
- soil pH and mineral content
- wind intensity and direction
- carbon dioxide levels
- oxygen levels
4 examples of biotic factors
- competition
- new pathogens
- new predators
- availability of food
what is the first trophic level and how do they transfer energy
- producers
- convert light energy into chemical energy - photosynthesis
what is the second trophic level and how do they transfer energy
- primary consumers
- eat producers, transferring energy in their tissues
what is the third trophic level and how do they transfer energy
- secondary consumers
- eat primary consumers, transferring energy in their tissues
what is the fourth trophic level and how do they transfer energy
- tertiary consumers
- eat secondary consumers, transferring energy in their tissues
what are food chains
diagrams that show the energy flow between organisms in an ecosystem
The arrows in a food chain represent the transfer of energy between trophic levels
what is pyramid of numbers
- Pyramids of numbers show how many organisms are present at each trophic level of a food chain
- The size of each bar indicates the number of organisms present
- pyramid of numbers will not be pyramid shaped
what is pyramid of biomass
- Pyramids of biomass show the mass of living organisms present at each level of a food chain
- pyramid of biomass are always pyramid-shaped
what is pyramid of energy
- Pyramids of energy illustrate the stored energy within the biomass at each trophic level
- As with pyramids of biomass, pyramids of energy are always pyramid-shaped
how much energy is transferred to each trophic level
10%
reasons why not all energy is transferred to each trophic level
- consumers are unable to digest and absorb all chemical energy
- organisms rarely consume every part of their prey
- not all ingested material is digested
- heat lost during respiration
- transfer into waste products
