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Population and Community

  • Community - Populations of diiferent species in a habitat
  • Population - All organisms of one species in one habitat

How to find out the size of a population: 

Number of organisms in the 1st sample X number of organisms in 2nd sample


Number of organisms in the 2nd sample that have been marked

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Ecosystem and Distribution

  • Ecosystem - All the organisms in a particular area as well as non-living (abiotic) conditions e.g. temperature, salintiy and soil quantity. 
  • Distribution - Where organisms are found within a particular area. You can investigate distribution using lines called transects. 
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Distribution of Organisms and Zonation

The distribution of organisms is affected by Abiotic Factors, these are:

  • Light
  • Temperature
  • Water
  • Oxygen
  • Salinity (Salt Level)
  • Soil Quantity

Changes in Abiotic Factors can lead to zonation. 

ZonationIs the gradual change in the distribution of species across a habitat

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  • The amount of variation between individuals of the same speieves in an area
  • The number of diffferent speices in an area
  • The number of different habitats in an area

The higher the biodiversity the healthier it is. 

Natural ecosystems have a higher biodiversity. 

  • Natural ecosystems maintain themselves without major intereference from humans
  • Artifical ecosystems are created and maintained by humans 
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  • Photosynthesis uses engery from the sun to change carbon dioxide and water into glucose and oxygen 
  • It takes place in chloroplasts in plants cells - they contain pigments like chlorophyll that absorbs light energy. 

Symbol Equation for Photosynthesis

6CO2 + 6H2O -----> C6 H12 O6 + 6O2

  • Light energy is used to split water innto oxygen gas and hydrogen ions
  • Carbon dioxide gas then combines with the hydrogen ions to make glucose and water
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Uses of Glucose in Plants


This releases energy so they can convert the rest of the glucose into various useful substances

Making Cell Wall

Glucose is conveerted into celluose for making cell walls

Stored as Starch

Glucose is turned into starch and stored in roots, stems and leaves to use when there isn't sun

Making Proteins

Glucose is combined with nitrates to make amino acids, which are then made into proteins. These are used for growth and repair. 

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