On the Wild Side Flashcards
Define ecosystem
Community of living organisms and their environment in an area which is self-sustaining
Define habitat
place where an organism lives
Define population
All the organisms of one species in a habitat
Define population size
The number of individuals of one species in a particular area
Define community
the various populations sharing a habitat
Define abiotic factors
non-living factors of the environment
Define biotic factors
living factors of the environment
Define distribution
Where a species is within a particular area
Why does population size vary?
Because of the abiotic factors
E.g. the amount of light, water or space
Because of the biotic factors
E.g. Interspecific competition, intraspecific competition and predation
What happens if the abiotic conditions are ideal for a species?
Organisms grow fast and reproduce successfully
E.g. when temp of a mammal’s surrounding is ideal for metabolic reactions to take place, they don’t use up as much energy maintaining body temp. More energy for growth and reproduction so population will increase.
Define interspecific competition
Competition between different species
Define intraspecific competition
Competition within a species
Explain intraspecific competition (5)
1) The population of a species increases when resources are plentiful
2) As population increases, they’ll be more organisms competing for the same amount of food and space
3) Eventually resources become limiting and population begins to decline
4) A smaller population means there is less competition for resources which is good for growth and reproduction so population grows
5) Carrying capacity is reached
Define predation
Where an organism kills and eats another organism. The population sizes of predators and prey are interlinked.
Why does distribution vary?
Because of abiotic factors
- Organisms can only exist where abiotic factors they can survive in exist
E.g. Some plants only grow on south-facing slopes in northern hemisphere ad solar input (light intensity) is greatest.
Because of biotic factors
- Interspecific competition, if 2 species are competing and one is better adapted the other is likely to be out-competed
E.g. the native red squirrel has disappeared from large areas as the grey squirrel has a better chance of survival because it’s larger and can store more fat for winter.
Define niche
The role of a species within it’s habitat
- Its biotic interactions
E.g. the organisms it eats and those its eaten by - Its abiotic interactions
E.g. the oxygen it breathes in and the carbon dioxide it breathes out
How many species can occupy a niche?
1
Explain abundance in terms of the niche concept
Two species occupying similar niches will compete so fewer individuals of both species will be able to survive in the same area.
Explain distribution in terms of the niche concept
Organisms can only exist in habitats where all the conditions that make up their role exist.
E.g. the soprano pipistrelle bat feds on insects and lives in farmland, open woodland, hedge lands etc. It couldn’t exist in a desert because there would be different insects.
What do you look at to investigate populations of organisms?
Abundance
- Estimated by counting the number of individuals in samples taken or using percentage cover for plants
Distribution
How do you avoid bias in your results?
The sample should be random
When is it necessary to do a non-random sample?
When in habitats where there’s a lot of variety in the abiotic features and/or distribution of species in the habitat and you want to make sure all the different areas or species are sampled
What is systematic sampling?
A type of non-random sampling.
Samples are taken at fixed intervals, often along a line
E.g. quadrats placed along a transect in a habitat where the abiotic factors change gradually from one end of the sample to the other (environmental gradient)
What are the benefits of using a frame quadrat
Useful for quickly investigating areas with species that fit within a small quadrat
How to calculate the percentage cover using a frame quadrat?
Count how much of the quadrat is covered by the plant (you count a square if its more than half covered)
What are transects?
A line to help find out how plants are distributed across an area.
There are 3 types:
- Line transects
- Belt transects
- Interrupted transects
What is a line transect?
A tape measure is placed along the transect and the species that touch the tape measure are recorded
What is a belt transect?
Data is collected along the transect using frame quadrats placed next to each other
What is a interrupted transect?
Instead of investigating the whole transect of either a line or belt, you take measurements at intervals
What is topography?
The shape and features of the earth’s surface
What are edaphic factors?
Soil conditions
How can you measure dissolved oxygen levels in aquatic habitat?
Using a oxygen sensor
How can you measure humidity?
Using an electronic hydrometer
How can you measure rainfall?
Using a rain gauge
What is succession?
The process by which an ecosystem changes over time. The biotic conditions change as the abiotic conditions change
What is primary succession?
This happens on land that’s been newly formed or exposed. There is no soil or organic material to start with, e.g. bare rock.
What is secondary succession?
This happens on land that’s been cleared of all the plants but where the soil remains, e.g. after a forest fire or deforestation
What are the stages of succession?
1) Primary succession starts when a species colonise a new land surface (pioneer species)
- seeds and spores are blown in by the wind and begin to grow
- the abiotic conditions are hostile (only pioneer species grow as they’re specially adapted to cope)
2) Pioneer species change the abiotic conditions as they die and microorganism decompose the dead organic material (humus). This forms basic soil
3) Makes conditions less hostile so new organisms with different adaptations move in and grow
4) These then die and are decomposed adding more organic material, making the soil deeper and richer in minerals
5) Larger plants such as shrubs can now grow in deeper soil
6) Some new species may change the environment so it becomes less suitable for previous species
7) Secondary succession happens in same way but soil layer is already there so succession starts at a later stage.
- pioneer species are larger plants (e.g. shrubs)
8) At each stage, different plants and animals that are better adapted for improved conditions move in and out-compete the organisms already there. They become the dominant species.
9) The ecosystem becomes more complex
- new species move in alongside existing species so biodiversity increases
10) The final stage is called the climax community
- the ecosystem is supporting the largest and most complex community of plants and animals it can.
- it won’t change much more so is in a stable state
What determines what species make up the climax community?
The climate in the ecosystem
Define plagioclimax
When succession is stopped artificially
Define phosphorylation
Adding phosphate to a molecule
E.g. ADP is phosphorylated to ATP
Define photophosphorylation
Adding phosphate to a molecule using light``
Define photolysis
The splitting of a molecule using light energy