Introduction:
Reproduction is the process of producing offspring from the parents. In human beings, reproduction is sexual and requires the fusion of male and female gametes.

Need of Opposite Sex Organs:
The human reproductive system consists of male and female sex organs which are designed to produce and transport gametes. The male and female gametes are required for fertilization to occur, which is the fusion of sperm and egg. The need for opposite sex organs is because:

- Production of Gametes: Male and female sex organs produce different types of gametes. Male sex organs produce sperm whereas female sex organs produce eggs. Sperm and eggs are required for fertilization to occur as they contain half of the genetic information required for the offspring.

- Fertilization: Fertilization occurs when a sperm penetrates an egg. The sperm provides the genetic information from the father, and the egg provides the genetic information from the mother. This results in the formation of a zygote, which is the first cell of the offspring.

- Pregnancy: The female reproductive system is designed to carry and nourish a developing fetus. The uterus provides a safe and secure environment for the embryo to develop into a fetus. The male reproductive system provides the sperm required for fertilization to occur.

Reproduction in Human Beings:
Human reproduction involves the following steps:

- Production of Gametes: The male sex organs produce sperm, whereas the female sex organs produce eggs. The testes produce sperm, whereas the ovaries produce eggs.

- Fertilization: Fertilization occurs when a sperm penetrates the egg. This results in the formation of a zygote, which is the first cell of the offspring.

- Implantation: The zygote travels down the fallopian tube and implants itself in the uterus. The uterus provides a safe and secure environment for the embryo to develop into a fetus.

- Development: The fetus develops inside the uterus and is nourished by the placenta. The placenta is an organ that connects the fetus to the mother and provides nutrients and oxygen.

- Birth: The fetus is born through the vagina during childbirth. The process of childbirth is stimulated by hormones, which cause the uterus to contract and push the fetus out.

Conclusion:
In conclusion, the need for opposite sex organs in human reproduction is crucial. The male and female sex organs produce different types of gametes, which are required for fertilization to occur. The process of reproduction involves the production of gametes, fertilization, implantation, development, and birth.

We need opposite sex cell for the fusion of gamete!^_^