In the process of grafting,what is the name given to the part of the plant that is attached to the cut stem of another plant?

Which contraceptive device is used only by males?

The spherical bacteria of the species $Neisseria$ $gonorrhoeae$ are responsible for which sexually transmitted disease in humans?

Which of the following two sex hormones are produced by the human female ovary?

Which among the following statements are true for sexual reproduction in flowering plants?
$(i)$ It requires two types of gametes
$(ii)$ Fertilisation is a compulsory event
$(iii)$ It always results in formation of zygote
$(iv)$ Offspring formed are clones

Differentiate between the following:
$(a)$ Pollen tube and style.
$(b)$ Bud of Hydra and bud of Bryophyllum.