2. If a nucleus has 8 chromosomes, how many chromosomes will be present after Telophase I? 3. What advantage does crossing-over have in reproduction? 6. Compare and contrast spermatogenesis and oogenesis (where do they occur, how many gametes are formed, when do they develop, etc):

Telophase I: 8 chromosomes composed of two sister chromatids  

Crossing over refers to the mechanism of recombination, this process being characterized in that increases the genetic variation

Spermatogenesis refers to the mechanism of formation of male gametes (sperms), while oogenesis is the process of formation of female gametes (oocytes)

Explanation:

Telophase I is the final step in meiosis I. During telophase I, the nuclear membrane is formed around the decondensed set of chromosomes and the nucleoli reappear.  

Spermatogenesis refers to the process by which haploid male germ cells (sperms) are generated within the seminiferous tubules in the testis, while oogenesis refers to the process of differentiation of the female egg cells (ova or oocytes) in the ovaries. Spermatogenesis is known to produce small and motile spermatic cells, while oogenesis is known to produce bigger non-motile oocytes.