life processes in the biosphere

• What must all organisms be adapted to in their habitat?

  Abiotic and biotic conditions
• How do species become better adapted?

  Through random mutations and natural selection
• What is the process called that involves adaptation and survival?

  Evolution
• What happens to poorly adapted organisms?

  They may die if conditions are unsuitable
• What does the range of tolerance refer to?

  Range of a factor within which survival is possible
• How does a large gene pool affect survival?

  It increases chances of surviving changes
• What is the relationship between range of tolerance and environmental change?

  A wider range increases survival chances
• Why is understanding adaptation important for environmental scientists?

  • Helps in understanding habitat requirements
  • Important for conservation management decisions
  • Aids in providing suitable survival conditions
• What primarily controls the survival and distribution of species?

  Abiotic factors
• What happens to survival when conditions become less suitable?

  Survival declines with fewer individuals
• Name three important abiotic factors affecting species distribution.

  Light, pH, water
• What must organisms be adapted to besides abiotic factors?

  Inter-species relationships and biotic factors
• What are some important biotic factors affecting species distribution?

  Food supply, pollination, seed dispersal
• Why is movement to colonize new habitats essential for species?

  To avoid extinction from unsuitable conditions
• What are the stages in ecological succession called?

  Seres
• What is the first living organism to colonize a new habitat called?

  Pioneer species
• How do pioneer species affect the habitat over time?

  They change the habitat for new species
• What is a climax community?

  A stable community dominated by certain species
• What are the changes in biotic conditions during ecological succession?

  Nitrogen decreases, biomass productivity decreases
• What determines the type of woodland that develops in an area?

  Temperature and rainfall
• What is a hydrosere?

  Succession in freshwater habitats
• What happens as a lake fills in with organic matter?

  Conditions change, allowing new plants to survive
• What is a lithosere?

  Succession on bare rock
• What is the initial condition of a lithosere?

  Harsh and unsuitable for most organisms
• What is a psammosere?

  Succession that starts on sand
• What happens as plants colonize in a psammosere?

  Sand stabilizes and nutrient supplies increase
• What is a plagioclimax community?

  • A community maintained by human activity
  • Does not allow natural climax community to reform
  • Examples include grassland and heathland
• What is secondary succession?

  Re-colonization after disturbance of climax communities
• Why does secondary succession occur more rapidly than primary succession?

  Soil is already developed and seeds present
• What is Simpson's Diversity Index used for?

  Measuring biodiversity
• How can the total number of species be estimated?

  Using past rates of species discovery
• How many new species are discovered each year?

  About 20,000
• What is the current estimate for the total number of species?

  Between 5 to 100 million
• How many species have been named so far?

  Two million
• What challenges exist in estimating total species diversity?

  • Many species remain undiscovered
  • Inaccessible ecosystems hinder discovery
  • Discovery rates are declining
• What is one common way to measure biodiversity?

  Simpson's Diversity Index
• How can the total number of species be estimated?

  Using the past rate of species discovery
• What is the current rate of new species discovery per year?

  About 20,000 species
• What is the range of current estimates for total species?

  5 to 100 million species
• How many species have been named so far?

  Two million species