Final answer:
The ovum contributes half of the genetic material, all cytoplasm, cytoplasmic organelles including mitochondria with their own maternal DNA, and crucial nutrients for the early development of the zygote to an embryo after fertilization.
Step-by-step explanation:
The ovum contributes significantly to the zygote beyond just one half of the genetic material. The egg supplies all the necessary cytoplasm and cytoplasmic organelles, which are crucial for the development of the zygote into an embryo.
This includes the mitochondria, which have their own DNA and are inherited maternally. Thus, the mother's genetics influence not just half of the DNA, but also the mitochondrial DNA and the initial conditions required for embryonic development.
Upon fertilization, the female gamete completes meiosis and becomes an ovum, merging its genetic material with that of the sperm. The combined genetic instructions are necessary for the development of a human.
Additionally, the large amount of cytoplasm in the ovum provides critical nutrients to the developing zygote during its journey and implantation into the uterus. This role emphasizes the complexity and significance of oogenesis compared to spermatogenesis.