Ecology Flashcards
What are the 4 levels of ecological organisation
Individual organism
Population
Communities
Whole ecosystem
What is interdependence
All organisms in an ecosystem depend upon each other. If the population of one organism rises or falls, then this can affect the rest of the ecosystem
What is competition
Plants compete for light, water, space and minerals
Animals compete for food, mates and territory
Competition can be interspecific or intraspecific
What is an ecosystem
The interaction of a community of living organisms (biotic) with the non-living (abiotic) parts of their environment
What are 7 abiotic factors
- Light intensity
- Temperature
- Moisture levels
- Soil pH and mineral content
- Wind intensity and direction
- Carbon dioxide levels for plants
- Oxygen levels for aquatic animals
What are 3 biotic factors
- Availability of food
- New pathogens
- One species out competing another so the numbers are no longer sufficient to breed
What are the producers of biomass for life on Earth
Photosynthetic organisms
What are the 4 Trophic levels
Producer - Photosynthesises to produce glucose
Primary consumer - Eats producer
Secondary consumer - Eats primary consumer
Tertiary consumer - Eats secondary consumer
In a stable community the numbers of predators and prey rise and fall ……
In cycles
Belt transect practical method (6 Marks)
1 - Extend a measuring tape from one side of the habitat to another.
2 - Place a quadrat at 0m on the tape.
3 - Count the numbers/estimate percentage cover of each species.
4 - Use a key to identify each species.
5 - Record results in a table.
6 - Move the quadrat along the measuring tape.
Quadrat random sampling method (6 Marks)
1 - Divide the area to be sampled into a grid using measuring tapes placed at right angles to each other.
2 - Use random numbers to generate coordinates within the grid on which to place the quadrats.
3 - Place a quadrat at each coordinate.
4 - Count the numbers/estimate percentage cover of each species in each quadrat.
5 - Use a key to identify each species.
6 - Record results in a table.
7 - Calculate the average of each species
Explain the importance of the carbon and water cycles to living organisms
Maintaining this carbon balance allows the planet to remain hospitable for life
What does the carbon cycle do?
The carbon cycle returns carbon from organisms to the atmosphere to be used by plants in photosynthesis
Explain the role of microorganisms in cycling
materials through an ecosystem by returning carbon to the atmosphere as carbon dioxide and mineral ions to the soil.
Microorganisms help return minerals and nutrients back to the environment so that the materials can then be used by other organisms.
The effect of water availability on the rate of decay
With little or no water there is less decomposition because decomposers cannot survive
Without water, enzymes that decompose biological material cannot be excreted
The effect of temperature on the rate of decay
At colder temperatures decomposing organisms will be less active, therefore the rate of decomposition remains low
But eventually decomposers will be killed and enzymes will denature so decay will stop
The effect of oxygen on the rate of decay
Most decomposers need oxygen to survive and without it there is little or no decomposition.
However, some can respire anaerobically and still decay, used in biogas generators
What gas is produced by anaerobic decay
Methane
How to investigate the effect of temperature on the rate of decay of fresh milk by measuring pH change - (6 marks)
1 - Place 20 cm3 of fresh milk into three beakers
2 - Decide the three temperatures you will investigate. Write these onto the sides of the beakers.
3 - Use universal indicator paper or solution to determine the pH of the milk in the three beakers
4 - Cover each beaker in cling film and incubate at the appropriate temperature
5 - Use universal indicator paper or solution to determine the pH of the milk in the three beakers after 24, 48 and 72 hours
How does temperature affect the distribution of species in an ecosystem
For example, many species of bird fly south for the winter, in search of warmer climates
How does availability of water affect the distribution of species in an ecosystem
The distribution of many plants and animals change dependent on rainfall
How does composition of atmospheric gases affect the distribution of species in an ecosystem
Many species are unable to survive in areas that are very polluted and so have migrated to get away from these areas with high levels of toxic atmospheric gases
What is biodiversity
The variety of all species of organisms on Earth, or within an ecosystem
How does biodiversity increase stability of ecosystems
Reduces the dependence of one species on another for food and shelter
Where can pollution occur
Water - From sewage, fertiliser or toxic chemicals
Air - From smoke and acidic gases
Land - from landfill and from toxic chemicals
Why does deforestation occur
- Provide land for cattle and rice fields
- Grow crops for biofuels
5 ways to maintain biodiversity
- Breeding programmes for endangered species
- Protection and regeneration of rare habitats
- Reintroduction of field margins and hedgerows where farmers only grow one type of crop
- Reduction of deforestation and co2 emissions by governments
- Recycling resources
Why is only 10% of biomass transferred in each trophic level
- Not all the ingested material is absorbed as some is egested as faeces
- Some absorbed material is lost as waste, such as co2 and eater in respiration and water and urea in urine
What is food security
Food security is having enough food to feed a population.
Biological factors which are threatening food security include:
- Increasing birth rate
- Changing diets in developed countries means scarce food resources are being transported around the world
- New pests and pathogens
How can the efficiency of food production can be improved
Restricting energy transfer from food animals to the environment
- Limit movement
- Control temp of their surroundings
What is Genetic modification
Involves adding a specific stretch of DNA into the plant’s genome, giving it desired characteristics
GM crops could provide more food or food with an improved nutritional value such as golden rice
The carbon cycle
- Co2 is REMOVED from the air in photosynthesis by green plants and algae - they use the carbon to make carbs, proteins and fats
- Co2 is RETURNED to the air when plants, algae and animals respire.
- Decomposers respire when they turn mineral ions to the soil
- Co2 is RETURNED to the air when wood and fossil fuels are burnt, as they contain carbon from photosynthesis
The water cycle
- Suns energy causes evaporation
- Water vapour also from transpiration in plants
- Vapour rises and condenses to form clouds
- Water is returned to the land by precipitation
- Surface run off into the seas
- Cycle repeats
Factors that affect rate of decomposition
Temp - faster in warmer conditions
Water - grow faster in moist conditions, makes food easy to digest, needed for respiration
Oxygen - Most decomposers respire anaerobically
Method to investigate the effects of temp on decay
- Make a solution of milk and phenolphthalein indicator
- Add sodium carbonate which will cause the solution to become alkaline and therefore appear pink
- Place the tube in a water bath at a specific temperature
- Add lipase enzyme and begin stopwatch
- Time how long it takes before pink colour disappears
- Repeat at diff temps
What environmental changes affect the distribution of species in an ecosystem
- Water availability causes populations to migrate
- Temperature, insects move to hotter regions
- Atmospheric gas composition, some organisms cant grow in presence of to much sulphur dioxide
