Which contraceptive device is used only by males?

Differentiate between the following:
$(a)$ Placenta and uterus
$(b)$ Unisexual and bisexual flowers
$(c)$ Fertilization and germination

In the process of reproduction as used in $Spirogyra$,the organism splits itself into small pieces.
$(a)$ What is this process of reproduction called?
$(b)$ Will this type of reproduction be asexual or sexual reproduction? Answer with reason.
$(c)$ Is this process same as regeneration? Give reasons.

List two functions of the ovary in the human female reproductive system.

Differentiate between germination and fertilization.

Where are the female germ cells located in a flower?