Chapter 16

• What should you be able to describe by the end of the video?

  How to use quadrats and transects to determine the abundance and distribution of species in an ecosystem
• What are abiotic factors?

  Non-living factors that affect living organisms
• Name three examples of abiotic factors.

  Light intensity, temperature, and levels of moisture
• How do abiotic factors affect organisms?

  They vary from place to place and affect the number of different organisms found
• What technique do scientists use to determine the number of organisms in an area?

  Sampling
• What are the two ways scientists perform sampling?

  Random sampling and sampling along a transect
• What is a quadrat?

  A wooden or plastic square used for sampling organisms
• How is a quadrat used in random sampling?

  It is placed on the ground to count the number of organisms inside
• If scientists want to compare the number of ferns in light and dark conditions, what sampling method do they use?


  Random sampling
• Why is it important to place the quadrat a large number of times?

  To ensure valid results that accurately represent the whole area
• What is the equation to estimate the total population size of a species?

  Total population size = (Total area / Area sampled) × Number of organisms counted
• What is a transect?

  A line used to sample organisms across a habitat
• How do scientists use a transect in their research?

  They place a quadrat at intervals along the transect to count organisms
• Why might scientists use sampling along a transect?

  To investigate how the numbers of species change across a habitat
• What is an example of a habitat where sampling along a transect might be used?

  A sand dune
• How do species of plants change on a sand dune?

  They change as you move inland from the sea
• What should you do to get valid results when sampling along a transect?

  Carry out the transect a number of times
• What are the steps involved in random sampling using a quadrat?

  • Place the quadrat on the ground at random locations
  • Count the number of organisms inside the quadrat
  • Repeat this process multiple times to ensure valid results
• What is the process of sampling along a transect?

  • Place a tape measure across the habitat
  • Use a quadrat to count organisms at set intervals along the transect
  • Repeat the process to gather valid data on species distribution