Question

The key events in embryo development are given below which is the correct order of seequences
i) organogenesis ii) Fertilization iii) Gastrulation iv) Neurulation v) Cleavage

• A. v $\to$ ii $\to$ iv $\to$ i $\to$ iii
• B. ii $\to$ iii $\to$ v $\to$ i $\to$ iv
• C. iii $\to$ iv $\to$ ii $\to$ i $\to$ v
• D. ii $\to$ v $\to$ iii $\to$ i $\to$ iv

Answer 1

The correct option is D ii $\to$ v $\to$ iii $\to$ i $\to$ iv

• After an egg has been fertilized and has been implanted in the uterus, the developing form is known as the embryo. Organogenesis takes place during this embryonic phase. It is the process by which the three germ tissue layers of the embryo, which are the ectoderm, endoderm, and mesoderm, develop into the internal organs of the organism.
  
• Human fertilization is the union of a human egg and sperm, usually occurring in the ampulla of the Fallopian tube.
  
• Gastrulation is a phase early in the embryonic development of most animals, during which the single-layered blastula is reorganized into a multilayered structure known as the gastrula.
  
• The mitotic division starts as the zygote moves through the isthmus of the oviduct called cleavage towards the uterus.
• Neurulation in vertebrates results in the formation of the neural tube, which gives rise to both the spinal cord and the brain.
  
• So, the correct option is " ii → v → iii → i → iv ".