Question

Juvenile hormone is secreted by

• A. Corpora Allata
• B. Corpora Juvenile
• C. Brain
• D. Optic lobe

Hint:

Remember the primary endocrine organs in insects: - Brain $\rightarrow$ PTTH (stimulates prothoracic glands).
- Prothoracic Glands $\rightarrow$ Ecdysone (drives molting).
- Corpora Allata $\rightarrow$ Juvenile Hormone (retains larval characteristics).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Insect growth, molting, and metamorphosis are regulated by the endocrine system.
Key hormones include Prothoracicotropic Hormone (PTTH), ecdysone (molting hormone), and juvenile hormone (JH).
Detailed Explanation:
- Corpora Allata (1): These are a pair of endocrine glands located behind the insect brain. They secrete Juvenile Hormone (JH).
JH maintains the insect in an immature (larval or nymphal) state during molting.
As the insect matures, the concentration of JH decreases, allowing ecdysone to drive metamorphosis toward the pupal and adult stages.
- Brain (3): Neurosecretory cells in the brain produce PTTH, which stimulates the prothoracic gland.
- Prothoracic Glands: These glands secrete ecdysone, which initiates the molting process.
- "Corpora Juvenile" (2) is a fabricated term used as a distractor.
- The optic lobes (4) are brain structures involved in processing visual information and do not secrete juvenile hormone.

Step 2: Final Answer:
Juvenile hormone is secreted by the Corpora Allata.