Which kind of contraceptive methods prevents $STDs$ and how?

Organisms have a varied body design. Name the property which gives the basic difference in body design.

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?

From the internet,gather information about the chromosome numbers of five animals and five plants. Correlate the number with the size of the organism and answer the following questions.
$(a)$ Do larger organisms have a higher number of chromosomes/cells?
$(b)$ Can organisms with fewer chromosomes reproduce more easily than organisms with a higher number of chromosomes?
$(c)$ Does a higher number of chromosomes/cells imply greater $DNA$ content? Justify.

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

Write true or false for the statement: The development of the child inside the mother's body takes approximately eleven months.