Topic 7 - ecology (in GCSE) Flashcards
4 levels of organisation in an ecosystem
Individual, population, community and ecosystem
What is an ecosystem
The interaction between the living component and non-living components
State the 4 factors that plants may compete for
Light, space, water and mineral ions from the soil
State the 3 factors that animals may compete for
Food, mates and territoy
What is intraspecific competition
Competition within a species
What is interdependance
Different species in an ecosystem depend on each other for varioud resources, if one species is are removed, the whole community may be afected
Wat is a stable community
A community in which all the biotic factors and all the abiotic factors are balanced so that population sizes remain relitively constant
What are abiotic factors
Non-living factors
State 5 abiotic factors that may affect an ecosystem
Light intensity, temp, moisture, wind intensity and direction, soil pH, carbon dioxide/oxygen levels
What may light intensity affect an ecosystem
Different species of plants have different optimum ligh intensities
Why does temperature affect an ecosystem
Different species of plants and animals have diffeent optimum tempertures for growth and survival
Why does soil pH affect an ecosystem
Certain plants may grow better in either alkaline or acidic soil, soil pH may affect the appearance of the plant
Why does wind intensity affect an ecosystem
Plant seeds are more likely to germinate in locations with lower wind inensity
Example of plants that have adapted to low soil mineral content
Carniverous plats that catch insect to compensate for the low levels of minerals in the soil
4 biotic factors that mau affect an ecosystem
Food availability, new predators, new pathogens, competition
Define population
A species that occupy the same habitat
Define habitat
The place in which an orgnism lives
Define community
Populations of different species interacting
What do food chains show
the feeding relationship of different organisims and the flow of energy between the organisms
Define biomass
The total dry mass of living material
What are biotic features
living factors
What do arrows show in a food chain
The direction of biomass transfer
Describe a general food chain
Producer-> primary consumer -> secondary consumer -> tertiary consumer
What is a producer
An organism that makes it’s own food
What types of organisms are producers
Photoynthetic organisms, that trap the energy from the sun
What is a primary consumer
An organism that feeds on producers
What is a secondary consumer
An organism that feeds on primary consumers
What is interspecific competition
Competition between different species
What is a tertiary consumer
An organism that feeds on secondary consumers
What is a predator
A consumer that kills and eats other animals
What is prey
An animal that is killed and eaten by another animal
Describe the pattern of predators and prey in a stable community
The number of predators and prey rise and fall in cycles
What apparatus is used to measure the abundance and distribution of organisms in an area
Quadrat
What apparatus is used to study the distribution of organisms across a gradiet
Belt transect
When considering the abundance of organisms, what is meant by the term ‘mean’
The average number of organisms
How is arithmetic mean calculated
Sum of each number of each organism divided by the totl number of ach type of organisms
Why have humans’ consumption of resources and waste production increased
Rapid rise in population, increased in standard of living
3 places polution occurs
air, land, water
3 examples of water pollutants
sewage, fertiliser and chemicas
How does eutrophication occur
Fertilisers from farms pollute water and cause excessive growth of algae which depletes the oxygen content in water so animals die, dead plants and animals are decomposed by bacteria which decreases oxygen levels further
2 examples of air pollution
Smoke, acidic gases
2 examples of land polution
chemicals, landfill waste
How materials cycle through the living and non-living componants of an ecosystem (4)
- Organsims take in elements from their surroundings, e.g. soil,air
- Elements converted to complex molecules which become biomass
- Elements transferred along food chains
- Elements returned to the environment during excretion and decomposition of dead organisms
3 molecules cycled through ecosystems
Oxygen, Carbon dioxide, water
Describe the carbon cycle (4)
- Plants fix carbon dioxide into organic molecules during photosynthesis
- THE organic carbon-containing molecules arepasses onto organisms that eat the plants
- Carbon dioxide is released back inot the atmosphere by respiration from animals and plants
- Burning fossil fuels also release carbon dioxide inot the atmosphere
Why is the carbion cycle important
Carbon-containing molecules like glucose are important for living organisms to grow and provide energy for vital funmctions within cells
Describe the water cycle (4)
- water from lakes and oceans evaporates
- Evaporated water condenses inot clouds and returns to earth as precipitation
- Water from precipitation is useful for life on land
- Water then returns to rivers and oceans through surface run-off
Why is water cycle important
L:iving organisms require water and the cycle provides organisms on land with a continuous supply of water
Why microorganisms important for material recycling
Return carbon to environment by releasing carbon dioxide when respiring when decomposing dead matter. Decomposition of material returns mineral ions to soil to be used for other organsims
What is decomposition
The breakdown or dead material inot simpler organic matter
How decomposers decompose dead matter
Release enzymes which catalyse breakdown of dead material inot smaller molecules
2 types of decomposition
Aerobic decomposition and anaerobic
3 factors that affect rate of decomposition
Oxygen availability
temperature
water content
Why oxygen needed in decomposition
Most decomposers require oxygen for aerobic respiration
How decomposition still occurs without oxygen
Some decomposers can respire anaerobically, but it is slower as less energy is produced
How water content affects decomposing rate
Need water to survive
Water needed for secretion of enzymes and absorbtion of dissolved molecules
but waterlogged soil reduces oxygen so rate decreases
How temp affects decomposition rate
50 degrees is optimum, then denatures
What is compost
Nutrient rich product of the rapid decay of waste biological material in optimum conditions set by gardeners and farmers
How compost used
Natural fertiliser to promote crop and garden plant growth
Describe how biogas generators work
Provide methane gas for fuel through anaerobic decomposition that occur in animal waste
4 Human activities that reduce land available for animals and plants
- Building
- Farming
- Quarrying
- Landfill
Why have peat bogs been destroyed
To produce compost to increase food production
Why does destruction of peat bogs greatly contribute to greenhouse effect
They stored carbon and buring them has released a large volume of carbon dioxide
How to calculate efficiency of biomass transfer
(Energy transfered/ total energy) x 100
% of incident energy from light for photosyntheis producers transfer
1%
% of biomass from one trophic level to another
10%
4 reasons biomass transfer not 100%
- Egestion
- Excretion removes waste products
- respiration where large amounts of glucose is used
- Parts of organism is inedible
4 biological factors affecting food security
- Rising birth rate
- Changing diets
- New pests and pathogens
- Increased agriculture cost
