Which of the following is the first major event in animal development?Multiple choice question.OrganogenesisGastrulationFertilizationCleavage

Breakdown the Problem

1. Identify the stages of animal development.
2. Determine the order of these developmental stages.

Relevant Concepts

• Fertilization: The union of sperm and egg to form a zygote.
• Cleavage: The rapid cell divisions that follow fertilization, leading to the formation of the blastula.
• Gastrulation: The process that transforms the blastula into a multi-layered structure.
• Organogenesis: The phase where the three germ layers develop into organs and tissues.

Analysis and Detail

1. Fertilization occurs first when the sperm fertilizes the egg.
2. Following fertilization, the cleavage begins where the zygote divides rapidly, creating a multicellular structure.
3. Gastrulation follows cleavage, reorganizing the cells into three germ layers.
4. Finally, organogenesis involves the development of organs from these germ layers.

Verify and Summarize

The correct order of events begins with fertilization. Therefore, fertilization is the first major event in animal development.

Final Answer

The first major event in animal development is Fertilization.