[Campbell Biology P.1055] Based on Figure 45.12, which of the following statements correctly ... | Practice Question

Based on Figure 45.12, which of the following statements correctly describes the roles of ecdysteroid and juvenile hormone JH in insect metamorphosis?

  • A: Ecdysteroid promotes pupa formation regardless of JH levels.
  • B: High JH levels stimulate metamorphosis into an adult.
  • C: Ecdysteroid triggers molts, while the concentration of JH determines if the molt results in another larval stage or pupa formation.
  • D: Low JH levels lead to continued larval stages without pupation.
  • E: PTTH directly inhibits ecdysteroid production.

Explanation

Figure 45.12 clearly illustrates that ecdysteroid triggers molts, while juvenile hormone JH acts as a modulator. High concentrations of JH suppress metamorphosis, leading to successive larval stages, whereas low concentrations of JH permit pupa formation during the next ecdysteroid-induced molt.