Ecology: Organisms and Their Environments
Test Your Knowledge!
Population Ecology Questions
- 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?
- What is MSY, and why is it difficult to use in practice?
- What do life histories tell ecologists about populations?
Species Interactions Questions
- Without looking, name the three main types of species interactions.
- What are some examples of mutualism? Parasitism? Commensalism?
- What is the difference between primary and secondary succession?
Ecosystems Habitats Questions
- What are the two main parts of an ecosystem?
- Why are plants the most abundant form of life on Earth?
- What are the most important abiotic factors in an ecosystem?
Population Ecology Answers
- 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.
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.
- 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
- Answer: The three types are competition, predation, and symbiosis.
- Answer: Mutualism—pollinators-plants. Parasitism—mosquitoes-humans. Commensalism—remora-sharks.
- Answer: Primary succession only occurs after a complete and total disturbance. Secondary succession occurs after partial disturbance events.
Ecosystems Habitats Answers
- Answer: The two main parts are the community and the habitat.
- 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.
- Answer: The most important abiotic factors are solar energy, water, carbon, nitrogen, and phosphorous.
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