This can be identified as a population. In a population, the organisms are the same species and they have to live in the same area. For example, the population of cities are the head count of the species of human in that one area.
The shuffling of chromosomes that occurs during both fertilization and meiosis can lead to genetic variation. This is because of the independent assortment and crossing over. Hope this answers the question. Have a nice day. Feel free to ask more questions.
Answer:
Topsoil is the part of a soil profile that is made up of partly weathered rock.
Hope this helps :)