Question

A laboratory investigation examined the growth rate of fruit flies in culture jars over time. The fruit flies were grown in an artificial medium containing nutrients and moisture. They were enclosed in a culture jar of a defined size. Initially, there were ten fruit flies in the experiment. The population reached 75 over the course of four weeks. However, after eight weeks, the population size leveled off and then decreased. Survival of fruit fly larvae declined after eight weeks. Which hypotheses are supported by the information in this scenario? Select the THREE that apply.
Responses
A The older fruit flies were unable to reproduce.The older fruit flies were unable to reproduce.
B The carrying capacity was exceeded by the fly population.The carrying capacity was exceeded by the fly population.
C Food was abundant for the first four weeks of the experiment.Food was abundant for the first four weeks of the experiment.
D The fruit flies were unable to survive in a laboratory setting.The fruit flies were unable to survive in a laboratory setting.
E The carrying capacity decreased when no new food was added to the culture jars.

Answer 1

Correct answers: B, C, and E.

- B: The population leveling off and then declining is consistent with an overshoot of the environment’s carrying capacity followed by a die‑off.
- C: Rapid growth from 10 to 75 in the first four weeks indicates food/resources were plentiful during that period.
- E: With no new food added, available resources decline over time, effectively lowering the jar’s carrying capacity and contributing to the later drop in survival.

A and D are not supported by the information given.