Ecosystems

• define community?

  A group of independent organism that are made up of different species
• define ecosystem?

  A community of living organisms and their physical environment, interacting as a system.
• what are abiotic factors?

  Non-living factors in an ecosystem e.g light intensity , soil PH , wind
• what are biotic factors?

  Living organisms in an ecosystem e.g predators
• what is interdependence?

  how species within a community depend on each other to survive
• A disease kills a large area of trees , is the death caused by a abiotic or biotic factor ?

  biotic factor diseases are living things
• why would reducing light intensity may decrease animal population?

  less light = less photosynthesis by plants = poor plant growth = less plant available to eat = less herbivores grow and survive =affects the food chain
• what are 3 things animals compete for?

  territory

  mates

  food
• what are the 4 things plants compete for?

  light

  space

  water

  mineral ions
• why is dispersal of seeds an adaptation?

  seeds are carried further away from parent plant so seed doesnt compete with parent plant
• biotic factors that affect ecosystems are?

  • availability of food

  • new predators arriving

  • new pathogens
• 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
• Some organisms live in environments that are very extreme, such as at high temperature, pressure, or salt concentration. These organisms are called extremophiles.
• what are structual adaptations?

  Physical traits or features that help an organism survive
• what are functional adaptations?

  how the body operates to survive e.g camels dont sweat
• what are behavioral adaptations?

  Changes in behavior that help an organism survive and reproduce in its environment.
• All food chains begin with a producer which synthesises molecules
• producers are usually a green plant or alge which makes glucose by photosynthesis
• Producers are eaten by primary consumers, which in turn may be eaten by secondary consumers and then tertiary consumers
• In a stable community the numbers of predators and prey rise and fall in cycles
• what factors affect decomposition?

  temperature

  water

  oxygen availability
• how temperature affects decay?

  increasing the temperature increases the rate of decay as there are more chemical reactions occurring
• how does water affect decay?

  more water (moist) increases rate of decay as microorganism need water for cell processes
• how does oxygen availability affect decay?

  rate of decay is faster as more oxygen means more respiration and most decomposers use aerobic respiration
• Gardeners and farmers try to provide optimum conditions for rapid decay of waste biological material. The compost produced is used as a natural fertiliser for growing garden plants or crops.
• Anaerobic decay produces methane gas
• Biogas generator is a device that converts biomass (waste from animals) into methane gas for fuel
• Environmental changes affect the distribution of species in an ecosystem. These changes include?

  • temperature

  • availability of water

  • composition of atmospheric gases
• Biodiversity is the variety of all the different species of organisms on earth, or within an ecosystem
• Biodiversity is the variety of all the different species of organisms on earth, or within an ecosystem
• Many human activities are reducing biodiversity such as deforestation
• Rapid growth in the human population and an increase in the standard of living mean that increasingly more resources are used and more waste is produced
• how does deforestation increase co2 emissions?

  less trees so fewer photosynthesis occurring

  the process of cutting down trees releases co2 emissions
• how does pollution happen?

  • in water, from sewage, fertiliser or toxic chemicals

  • in air, from smoke

  • on land, from landfill and from toxic chemicals.
• Humans reduce the amount of land available for other animals and plants by:

  • building
  • farming
  • dumping waste.
• The destruction of peat bogs, and other areas of peat to produce garden compost, reduces the area of this habitat and the variety of different plant, animal and microorganism species that live there (less biodiversity).
• deforestation causes?

  provides land for cattle and rice fields and grow crops for biofuels.
• how have scientist maintained biodiversity?

  • breeding programmes for endangered species

  • protection and regeneration of rare habitats

  • reduction of deforestation and carbon dioxide emissions

  • recycling resources rather than dumping waste in landfill.
• what are trophic levels?

  Different positions in a food chain occupied by organisms
• what is biomass?

  the mass of material in an organism