The answer would be the species’ niche. A niche includes all the interactions of a species.
It is important that a gamete or sex cells have exactly only one set of chromosome because during sexual reproduction two sex cells of the parents will form the zygote and it will have 2n or diploid number of chromosomes. It is from this zygote somatic cells are formed.
1. sewage system - facility consisting of a system of sewers for carrying off liquid and solid sewage. sewage works, sewer system. facility, installation - a building or place that provides a particular service or is used for a particular industry; "the assembly plant is an enormous facility"