How are Sexual hierarchies  constructed and reproduced

Explain isogamous and its types?

Sexual reproduction involves crossing-over to mix up genes. Is this a good thing or a bad thing? In the discussion this week explain one pro and one con to crossing-over. Overall, what is your opinion of crossing-over? Can evolution occur without it? (Min. 50 words)

how does sexual reproduction produce more complex offspring, produce a greater number of offspring, enhances the genetic variability, produce more evolutionary fit individual and Increases the survival rate of the species?

In fertilization,  select answer   a male gamete and a female gamete two female gametes two male gametes  fuse to produce a      select answer   zygote female germ cell male germ cell

Why do biologists believe that isogamy is the ancestral state? Given isogamy as a starting point, explain the evolution of anisogamy.