Polio viruses contain DNA. The viruses in the polio vaccine have DNA in which the base sequence has several differences from the base sequence in the normal polio virus. Suggest how this makes them unable to reproduce in the human body.

Amale bird-of-paradise uses a dance to attract mates in which it flaps its tail feathers on the ground and jumps around a potential female mate. a different male bird-of-paradise does a similar dance but it jumps around the female in the opposite direction. the female bird is only attracted to one style of dance, in one direction. this is an example of speciation.