The development of the embryo takes place inside the eggshell after it is laid.
Explanation
In animals, fertilization can be internal or external. Based on where the embryo develops, animals are classified as oviparous (egg-laying) or viviparous (giving birth to live young). Hens are oviparous animals that undergo internal fertilization but external embryonic development.
Detailed Analysis:
- The embryo develops fully inside the hen's body before the egg is laid. is Incorrect: The embryo does not develop fully inside the hen's body. While fertilization is internal and the zygote begins to divide as it travels down the oviduct, the egg is laid before the embryo is fully formed.
- The development of the embryo takes place inside the eggshell after it is laid. is Correct: After fertilization, protective layers (including the hard calcareous shell) are formed around the developing embryo. The hen then lays the egg. The subsequent development of the chick takes place inside the eggshell during an incubation period (approximately 21 days), provided sufficient warmth is maintained.
- The fertilization and development both occur externally in the soil. is Incorrect: Fertilization in hens is internal, occurring inside the female body. It does not occur externally in the soil.
- The embryo requires water for development after the egg is laid. is Incorrect: The hard shell of the egg prevents desiccation, and the egg contains albumen (egg white) which provides the necessary moisture and nutrients. Unlike amphibians, bird eggs do not require an external water medium for development.
Key Takeaway:
Hens exhibit internal fertilization but are oviparous; the development of the chick occurs externally inside a hard calcareous shell after the egg is laid.