B7 - Ecology Flashcards
Habitat - definition
> The place where an organism lives
Population - definition
> All the organisms of one species living in a habitat.
Community - definition
> The populations of different species living in a habitat
Abiotic factors- definition
> Non-living factors of the environment, e.g. temp.
Biotic factors - defintion
> Living factors of the environment, e.g. food.
Ecosystem - definition
> An ecosystem is the interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment.
Survival of organisms
> To survive and reproduce, organisms require a supply of materials from their surroundings and from the other living organisms there.
What do plants compete for?
> Plants in a community or habitat often compete with each other for light and space, and for water and mineral ions from the soil.
What do animals compete for?
> Animals often compete with each other for food, mates and territory.
Interdependence
> Within a community each species depends on other species for food, shelter, pollination, seed dispersal etc. If one species is removed it can affect the whole community. This is called interdependence.
A stable community is one where all the species and environmental factors are in balance so that population sizes remain fairly constant.
Example of stable communities
> Tropical rainforests
>Ancient oak woodlands.
Abiotic factors that can affect a community
Abiotic (non-living) factors which can affect a community are: • light intensity • temperature • moisture levels • soil pH and mineral content • wind intensity and direction • carbon dioxide levels for plants • oxygen levels for aquatic animals.
Abiotic factors that can affect a community - light, co2 or temp
> Could all affect rate of photosynthesis.
>So could affect plant growth and cause a decrease in the population size.
Abiotic factors that can affect a community - mineral content
> Could cause nutrient defeciencies.
>Affect plant growth and cause a decrease in pop size.
Abiotic factors that can affect a community - plants for food
> Animals depend on plants for food, so a decrease in a plants population could affect the animal species in a community.
Biotic factors that can affect a community
Biotic (living) factors which can affect a community are:
• availability of food
• new predators arriving
• new pathogens
• competition - one species outcompeting another so the numbers are no longer sufficient to breed.
Biotic factors that can affect a community - new predators
> A new predator could cause a decrease in the prey population.
Biotic factors that can affect a community - competition
> Red and grey squirrels live in the same habitat and eat the same food.
Grey squirrels outcompete the red quirrels - so the population of red squirrels is decreasing.
Adaptations
> Organisms have features (adaptations) that enable them to survive in the conditions in which they normally live. These adaptations may be structural, behavioural or functional.
Adaptation - definition
> Features or characteristics that allow organisms to live in different environmental conditions.
Adaptations - stuctural
> These are features of an organism’s body structure - such as shape or colour, for example:
- Arctic animals, arctic fox - white fur - camouflage - avoid predators - sneak up on prey.
- Animals in cold places, whale - thick layer of blubber + low surface area to volume ratio - helps retain heat.
- Animals in hot places, camel - thin layer of fat + large surface are to volume ratio - helps to lose heat.
Adaptations - behavioural
> There are ways that organisms behave.
Many species (e.g swallows) migrate to warmer climates during the winter to avoid the problems of living in cold conditions.
Adaptations - functional
> These are things that go on inside an organism’s body that can be related to processes like reproduction and metabolism. For example:
- Desert animals conserve water by producing very little sweat and small amounts of concentrated urine.
- Brown bears hibernate over winter - they lower their metabolism - conserves energy - so don’t have to hunt when less food about.
Microorganisms adaptations
> Some organisms live in environments that are very extreme, such as at high temperature, pressure, or salt concentration. These microorganisms are called extremophiles.
Bacteria living in deep sea vents are extremophiles.
Food chains
> Feeding relationships within a community can be represented by food chains.
All food chains begin with a producer which synthesises molecules.
This is usually a green plant or algae which makes glucose by photosynthesis.
When a green plant produces glucose, some of it is used to make other biological molecules in the plant.
These biological molecules are the plant’s biomass.
Biomass
> The mass of living material.
Biomass can be thought of as energy stored in a plant.
Energy is transferred through liing organisms in an ecosystem when organisms eat other organisms.
Consumer - definition
> Consumers are organisms that eat other organisms.
Primary condumer - defnition
> The first consumers in a food chain.
>Secondary =2nd, tertiary= 3rd.
Levels of a food chain
> Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers.
Predator-prey population
> Pop of any species is usually limited by amount of food available.
Pop of prey increases, so will op of predators.
As pop of predators increases, no. of prey decreases.
pREDATOr-prey cycles are always out of phase with each other as it takes a while for pop to repond to changes in other population - (as it takes take for them to reproduce for example.)
Investigating species in area.
> A range of experimental methods using transects and quadrats are used by ecologists to determine the distribution and abundance of species in an ecosystem.
Predators
> Consumers that kill and eat other animals are predators, and those eaten are prey.
In a stable community the numbers of predators and
prey rise and fall in cycles.
Quadrats
> A quadrat is a square frame enclosing an area , e.g. 1m^2.
Used to compare how common an organism is in two sample areas (e.g. shady and sunny spots).
1. Place a 1m^2 quadrat on ground at a random point within first sample area. Get random point by dividing area into grid and use random number generator to select co-ordinates.
2. Count all organisms within quadrat.
4. Repeat as many times as you can.
5. Work our mean number of organisms per quadrat (total no. divied by total no. of quadrats.)
6. Do in second area and compare.
If workout mean multiply by total area to find out population size of an organism in one area.
Transects
> Use transects to study the distribution of organisms along a line.
1. Mark out a line in the area you want to study using a tape measure.
2. Then collect data along the line.
3. You can do this by counting all the organisms you’re interested in that touch the line.
4. Or, you can collect data using quadrats. These can be placed next to each other along the line or at intervals.
Estimate percentage cover of a quadrat by counting squares with more than half covered with organism and divide by total then divide by 100.
impact of environmental changes on the distribution of species in an ecosystem
Environmental changes affect the distribution of species in an ecosystem. These changes include:
• temperature
• availability of water
• composition of atmospheric gases.
The changes may be seasonal, geographic or caused by human interaction.
E.g. rise in temp caused by global warming caused by human activity.
environmental changes + distribution - availability of water
> Distribution of some animal and plant species in the tropics changes between the wet and dry seasons - time when more or less rainfall - more/less water available.
E.g. Africa each year, large no. of giant wildebeest migrate, moving north + then back south as rainfall patterns change.
environmental changes + distribution - temperature
> Distribution of bird species in Germany is changing due to rise in av. temp.
E.g. European bee-eater bird is a Mediterranean species but is now present in parts of Germany.
environmental changes + distribution - composition of atmospheric gases
> Distribution of some species changes in areas where there is more air pollution.
E.g. some species of lichen can’t grow in areas where Sulfur dioxide is given out by certain industrial processes.
How is water endlessly recycled?
> The water cycle provides fresh water for plants and animals on land before draining into the seas.
Water is continuously evaporated and
precipitated.
So its being endlessly recycled.
Water cycle
- Evaporation due to Sun’s energy. And transpiration from plants.
- Warm water vapour carried up, cools plus condenses into clouds.
- Precipitation. Feeds plants animals.
- Drains into sea.
