Which term describes the earliest stage of growth and development in plants and animals?

• A. Embryo
• B. Zygote
• C. Sperm
• D. Thinning

Answer: (A)

Growth and development begin once a fertilized egg starts to divide and organize into a multicellular form. The term embryo refers to that early, growing stage where cells are proliferating, differentiating, and forming the basic body plan. In both plants and animals, the embryo is the initial stage where an organized, developing organism becomes visible beyond a single cell. The zygote is the very first cell formed after fertilization, but the embryo represents the subsequent stage where growth takes on structure and form. Sperm is a gamete, not a developmental stage, and thinning isn’t a term used to describe early development.