A single cell includes many specialized parts and organelles to carry out various processes. For example, the endoplasmic reticulum is a complicated network of folded membranes with a large amount of surface area on which chemical reactions are carried out.

Which of the following statements best explains how the specialized parts of cells came to have their current form?

Ancient single-celled organisms competed for food, energy and raw materials. Natural selection favored cells that could compete effectively.

Explanation:

The theory of natural selection explains how organisms with the best characteristics are able to survive in an environment and pass on their characteristics to their organisms. Through the phenomenon of natural selection, evolution occurs and species tend to evolve into new species. The same phenomenon goes for the cells. Ancient prokaryotes competed for food, energy an other materials. Those prokaryotic cells which were better adapted were favoured by natural selection.