At what age do boys typically reach puberty?

Can we find variations in an asexually reproducing organism like bacteria? Write yes or no and give a reason in support of your answer.

Which method of plant propagation is used to obtain high-quality mangoes from a common mango tree?

$(i)$ $(a)$ Write the full form of $DNA$.
$(b)$ State the role of $DNA$ in the cell nucleus.
$(c)$ What will be the after-effect if the information of the $DNA$ is changed?
$(ii)$ Explain the importance of $DNA$ copying in reproduction.

State the importance of chromosomal difference between sperms and eggs of humans.

Factors responsible for the rapid spread of bread mould on slices of bread are:
$(i)$ Large number of spores
$(ii)$ Availability of moisture and nutrients in bread
$(iii)$ Presence of tubular branched hyphae
$(iv)$ Formation of round-shaped sporangia