Which is the primary sex organ of the male reproductive system?

Which method of asexual reproduction is observed in $Spirogyra$?

Explain the term "Regeneration" as used in relation to reproduction of organisms. Describe briefly how regeneration is carried out in multicellular organisms like $Hydra$.

What is produced by the fusion of a male gamete and a female gamete?

Length of pollen tube depends on the distance between :

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