Which method of asexual reproduction is observed in Protozoa?

At approximately what age does menstruation permanently cease in females?

What is placenta? Describe its structure. State its functions in case of a pregnant human female.

Which among the following statements are true for unisexual flowers?
$(i)$ They possess both stamen and pistil.
$(ii)$ They possess either stamen or pistil.
$(iii)$ They exhibit cross-pollination.
$(iv)$ Unisexual flowers possessing only stamens cannot produce fruits.

Length of pollen tube depends on the distance between

In human males,the testes lie in the scrotum,because it helps in the