Age structure Knowledge-Based Download PDF

Questions

1. 1.

   In population ecology, which of the following best explains the phenomenon of demographic momentum, where a population continues to grow in size even after fertility rates fall to replacement level?

   • A) A large proportion of the population is currently in the pre-reproductive cohort and will soon enter their reproductive years.
   • B) The average lifespan of post-reproductive individuals increases dramatically to compensate for reduced birth rates.
   • C) The carrying capacity of the habitat expands rapidly in response to the changing age distribution.
   • D) Reproductive-age individuals experience an immediate increase in their physiological fecundity.
2. 2.

   In population ecology, why does a selective disturbance that removes only pre-reproductive individuals produce no immediate change in the population's current birth rate?

   • A) Current birth rates depend entirely on the abundance and fecundity of individuals currently occupying the reproductive age class.
   • B) Post-reproductive individuals re-enter the breeding pool to compensate for the lost juvenile cohort.
   • C) Eliminating the pre-reproductive cohort instantly shifts the population sex ratio in favor of reproductive females.
   • D) Surviving juveniles accelerate their physiological development within hours to restore the baseline cohort size.
3. 3.

   In population ecology, which of the following demographic conditions is characteristic of a population exhibiting a stable, bell-shaped age structure?

   • A) A much larger proportion of pre-reproductive individuals than reproductive individuals, leading to rapid population growth.
   • B) Approximately equal proportions of pre-reproductive and reproductive individuals, resulting in a stationary population size.
   • C) A severely depleted post-reproductive cohort caused by an immediate collapse in adult life expectancy.
   • D) A significantly smaller pre-reproductive group compared to reproductive and post-reproductive groups, causing a rapid decline.
4. 4.

   In population ecology, which of the following demographic features characterizes an urn-shaped age structure?

   • A) A broad base where pre-reproductive individuals significantly outnumber all older age classes
   • B) An equal proportion of pre-reproductive and reproductive individuals that produces a stationary population
   • C) A complete absence of post-reproductive individuals resulting from severe density-dependent mortality
   • D) A narrow base where the proportion of pre-reproductive individuals is smaller than that of reproductive individuals
5. 5.

   In an ecological survey of a natural population, researchers observe that the proportion of individuals in the pre-reproductive age group is significantly larger than the proportions in the reproductive and post-reproductive age groups. Which of the following best describes the future demographic trend of this population under stable environmental conditions?

   • A) The population size will experience rapid growth as the pre-reproductive cohort matures.
   • B) The population size will immediately decline due to a shortage of current breeding adults.
   • C) The population will remain completely stable because the post-reproductive group has no ecological impact.
   • D) The population will invert its sex ratio to compensate for the smaller reproductive class.