SB9 - Ecosystems and Material Cycles ✓ Flashcards Preview

Edexcel GCSE Biology (9-1) > SB9 - Ecosystems and Material Cycles ✓ > Flashcards

Flashcards in SB9 - Ecosystems and Material Cycles ✓ Deck (55)
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SB9a - Define an Ecosystem

An ecosystem is all the organisms and the habitat in which they live


SB9a - Define a Community

All the organisms that live and interact in an ecosystem


SB9a - Define a population

The total amount of one species in a population


SB9a - Define Interdependence

When organisms depend on each other for resources within an ecosystem.


SB9a - What's the equation for population size using quadrats?

Population size


(total size of area where organism lives ÷ total area of quadrats)     x

number of organisms in all quadrats


SB9b - Once a plant has taken in energy from the sun, where does the energy get transferred to?

Much is transferred to plant biomass. The rest is transferred to the environment by heating during the life processes.


SB9b - Why isn't energy transferred to surroundings by heating useful?

Other organisms can't use it.


SB9b - Why does a secondary consumer need to eat more then a primary consumer?

  • Only some of the energy from the PC's diet is converted to biomass and the rest is wasted by transferring to heat in the surroundings.
  • Therefore to get the same amount of energy, the SC will need to eat more.
  • This is why there is a limit to the size of a food chain.


SB9b - What happens to the biomass at each trophic level (on a pyramid of biomass)

It reduces significantly.


SB9b - Why is a pyramid of biomass usually bottom heavy?

At each level more energy is being wasted so at each level there is less energy to be used and less biomass can be produced.


SB9b - Why is there a maximum limit to how many trophic levels a food chain can have?

Since there is less biomass at each level, after a certain level, the amount of the lower species you'd have to consume would be too high.


SB9c - What is the distribution of organisms?

Where organisms can be found in a food chain


SB9c - What is an abiotic factor?

A non-living factor that affects organisms


SB9c - Name some abiotic factors.

  • Abundance of Water
  • Light intensity
  • Temperature
  • Wind
  • Pollutants


SB9c - What about an organisms may mean that they are affected by abiotic factors.

  • An organisms adaptations.
  • If an adaptation is specific to a condition then an abiotic factor that affects that condition will mean that the organism is not longer adapted to their conditions


SB9c CP - Describe how to investigate the effect of Abiotic Factors on the ABudance of Low-Growing plants.

  • Create a hypothesis on the abiotic factor
  • Create a transect line, e.g starting where there is no shade and ending in heavy shade
  • Count the population of the species along the transect line using quadrats
  • Measure abiotic factors are each point
  • Compare


SB9d - What are biotic factors?

The organisms in an ecosystem that affect each other.


SB9d - What are the two main biotic factors?

  • Competition
  • Predation


SB9d - Describe what a predator - prey cycle is.

  • When a predator eats their prey the population of prey decreases.
  • Now there isn't enough food for the predator so their population decreases
  • Now that there is less predation, the prey's population can increase again
  • Now there is more food for the predator so their population can increase again.
  • This goes on and so the predator is affected slightly after the prey


SB9d - Explain why a predator - prey cycle may not be seen in larger ecosystems with more biodiversity.

  • In an ecosystem with more biodiversity, a predator doesn't prey on one species and a prey isn't predated by one species.
  • This means that it is unlikely that one species will ever cause another's population to decrease and if so, this wouldn't affect the other species.


SB9d - How can adding just one new species to an ecosytem be benefical to the biodiversity?

  • New species provide more habitats and/or food for many species.
  • For example in yellowstone when wolves were (re)introduced, this decreased elk numbers increasing beavers and increasing the amount of dams which altogether promoted the biodiversity of the ecosystem


SB9e - Name indicator species for levels of water pollution.

  • High levels of pollution:
    • Sludgeworm
    • Bloodworm
  • Low levels of pollution:
    • Stonefly nymph
    • Dragonfly nymph


SB9e - Name indicator species for levels of air pollution in terms of sulfur dioxide concentration

  • Lower levels of sulfur:
    • Blackspot fungus on roses
  • Higher levels of sulfur:
    • Lichens such as Lecanora conizaeoides


SB9d - Why is reforestation an effectivce way of preserving biodiversity?

  • Trees provide habitats and food for many species.
  • More trees is an effective way of making an ecosystem suitable for more species.


SB9e - Why may indicator species not be effective?

They don't give numerical/quantitative results and so aren't fully accurate and comparable especially as both air and water pollution can be numerically measured.


SB9f - What is a parasite?

An organism in a feeding relationship with another organism usually harmful to that other organism. e.g Lice and tapeworms


SB9f - What is a mutualist (symbiote)

An organism in a realtionship with another organism which is beneficial to both as they each provide something to each other. (e.g. bees and flowers or oxpecker and zebras)

V̶e̶n̶o̶m̶ ̶i̶s̶ ̶a̶ ̶f̶i̶c̶t̶i̶o̶n̶a̶l̶ ̶c̶h̶a̶r̶a̶c̶t̶e̶r̶ ̶a̶p̶p̶e̶a̶r̶i̶n̶g̶ ̶i̶n̶ ̶A̶m̶e̶r̶i̶c̶a̶n̶ ̶c̶o̶m̶i̶c̶ ̶b̶o̶o̶k̶s̶ ̶p̶u̶b̶l̶i̶s̶h̶e̶d̶ ̶b̶y̶ ̶M̶a̶r̶v̶e̶l̶ ̶C̶o̶m̶i̶c̶s̶,̶ ̶c̶o̶m̶m̶o̶n̶l̶y̶ ̶i̶n̶ ̶a̶s̶s̶o̶c̶i̶a̶t̶i̶o̶n̶ ̶w̶i̶t̶h̶ ̶S̶p̶i̶d̶e̶r̶-̶M̶a̶n̶.̶ ̶T̶h̶e̶ ̶c̶h̶a̶r̶a̶c̶t̶e̶r̶ ̶i̶s̶ ̶a̶ ̶s̶e̶n̶t̶i̶e̶n̶t̶ ̶a̶l̶i̶e̶n̶ ̶S̶y̶m̶b̶i̶o̶t̶e̶ ̶w̶i̶t̶h̶ ̶a̶n̶ ̶a̶m̶o̶r̶p̶h̶o̶u̶s̶,̶ ̶l̶i̶q̶u̶i̶d̶-̶l̶i̶k̶e̶ ̶f̶o̶r̶m̶,̶ ̶w̶h̶o̶ ̶r̶e̶q̶u̶i̶r̶e̶s̶ ̶a̶ ̶h̶o̶s̶t̶,̶ ̶u̶s̶u̶a̶l̶l̶y̶ ̶h̶u̶m̶a̶n̶,̶ ̶t̶o̶ ̶b̶o̶n̶d̶ ̶w̶i̶t̶h̶ ̶f̶o̶r̶ ̶i̶t̶s̶ ̶s̶u̶r̶v̶i̶v̶a̶l̶.̶


SB9g - Why is fish farming needed and what are the problems with it?

  • About 17% of the world's protein consumption is fish based.
  • However overfishing leads to loss of certain fish species.
  • So the solution is to farm fish.
  • Since so many fish are kept in a small space, all their uneaten food and faeces sink to the bottom creating a harmful atmosphere alowing parasites and disease to spread easily throughout fish.


SB9g - How may adding non-indigenous species to an ecosystem negatively effect biodiversity?

  • After humans have added new species to an ecosystem, these species may outcompete native species for resources meaning the native species reduce in numbers affecting the ecosystem.


SB9g - Describe the process of eutrophication.

  • Fertiliser is added
  • Heavy rain washes fertilisers off dissolving nitrates and phosphates into soil water
  • If plants take up the nitrates and phosphates and there is still some remaining this gets washed into streams and rivers
  • The high concentration of fertilising substances encourages rapid growth of algae and plants on water surface
  • Surface plants block sunlight and so plants in the water die as they stop photosynthesising
  • The decomposing bacteria increases in numbers and consumes more oxygen
  • Oxygen concentration in water decreases
  • Aquatic animals die due to anoxic water