Aspecies of fish is unintentionally introduced into a marine ecosystem. the species has a similar diet to an existing fish species creating competition on for food. according to darwin's theory of evolution by natural selection, which of the following must occur for the existing species to evolve? how do i explain the natural variations in phenotype must be present in the existing species population.

Facial shaving brushes are either bulb-shaped or fan-shaped. an experiment is to be conducted to determine whether the lather thickness is the same for both types of shaving brushes. in previous studies, it was determined that shaving brush size (small, medium, large) is associated with lather thickness, but shaving brush type (wolf whiskers, maggard razors, frank shaving, and so on) is not associated with lather thickness. how could the experiment best be conducted? by blocking on shaving brush size by blocking on shaving brush type by blocking on shaving brush shape by blocking on lather thickness without blocking

What statement is true about all chemical changes? a) chemical changes can be undone. b) chemical changes cannot be reversed. c) chemical changes change the color of objects. eliminate d) chemical changes do not form new products.

In which of the following conflicts did the distribution of ethnic groups act as a centripetal force? cyprus afghanistan north and south korea iraq former yugoslavia