how does the heterozygous advantage explain the large numbers of detrimental alleles(like sickle cell allele) in a population?

If you are in a chronic state of anxiety but also suffer from moment of sudden, intense fear you are problably suffering. from

All individuals have two alleles for a given trait. according to mendel's these alleles are passed down one each from both mother and father.

Adrought killed all the plants in an agricultural farmland. gradually, due to wind and some birds for. nearby areas, new plants started sprouting l. what stage of succession was taking place in the farmland? a) competition b) nudation c) ecesis d) reaction e) migration