Answer:
Refraction is the change in direction of waves that occurs when waves travel from one medium to another. Refraction is always accompanied by a wavelength and speed change. Diffraction is the bending of waves around obstacles and openings.
Most adult placental mammals have no remaining trace of the cloaca. Being placental animals, humans only have an embryonic cloaca, which is split up into separate tracts during the development of the urinary and reproductive organs.
