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Ecology: Organisms and Their Environments
Ecology: Organisms and Their Environments

Test Your Knowledge!

Population Ecology Questions

  1. A penguin population has 10,000 individuals. If 1,000 chicks were born and 2,000 penguins died in a year, what would the birth rate be? The death rate? The growth rate? Is overall growth positive or negative? What does this mean about the future size of the penguin population?
      
  2. What is MSY, and why is it difficult to use in practice?
      
  3. What do life histories tell ecologists about populations?
     

Species Interactions Questions

  1. Without looking, name the three main types of species interactions.
      
  2. What are some examples of mutualism? Parasitism? Commensalism?
      
  3. What is the difference between primary and secondary succession?

Ecosystems Habitats Questions

  1. What are the two main parts of an ecosystem?
      
  2. Why are plants the most abundant form of life on Earth?
      
  3. What are the most important abiotic factors in an ecosystem?
     

Population Ecology Answers

  1. Answer: The birth rate would be 0.1, and the death rate would be 0.2. The growth rate would therefore be 0.1 – 0.2 = -0.1. A negative growth rate means that the penguin population would be shrinking, or experiencing negative growth.
      
  2. Answer: MSY is Maximum Sustainable Yield and is exactly half of a population’s carrying capacity. It is difficult to use in practice because population size, carrying capacity, and age structures are hard to determine. Without these numbers, MSY isn’t extremely useful or exact.
      
  3. Answer: Life histories describe the age of first reproduction, probabilities of survival and reproduction at each age, litter size, litter frequency, and longevity for individuals in a population.

Species Interactions Answers

  1. Answer: The three types are competition, predation, and symbiosis.
      
  2. Answer: Mutualism—pollinators-plants. Parasitism—mosquitoes-humans. Commensalism—remora-sharks.
      
  3. Answer: Primary succession only occurs after a complete and total disturbance. Secondary succession occurs after partial disturbance events.

Ecosystems Habitats Answers

  1. Answer: The two main parts are the community and the habitat.
     
  2. Answer: Plants are producers and comprise the base of all energy pyramids. Because energy is passed so inefficiently from one trophic group to the next, it takes a bunch of producers to sustain a fewer number of consumers.
      
  3. Answer: The most important abiotic factors are solar energy, water, carbon, nitrogen, and phosphorous.
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