Answer: (B) Pre-zygotic; post-zygotic.
Explanation:
Prezygotic isolation occurs before fertilization of eggs. It occurs between the two sex gametes and deter sexual reproduction between different species.
However, individuals are considered to be diverge on the phylogeny tree and different species, when they cannot reproduce.
Mechanisms of prezygotic isolation include habitat isolation, gamete isolation, mechanical isolation, behavioral isolation, and mating seasons.
Whereas, postzygotic isolation prevents the formation of fertile offspring. This phenomenon leads to production of an hybrid offspring from different species and this is a form of speciation in nature.
Mechanisms of postzygotic isolation include hybrid inviability, hybrid breakdown, and hybrid sterility.
The object will continue to move north because there is no opposing force form the south and the other forces canceled each other out
Answer:
Electricity, gravity of earth and structure of atom provide evidence.
Explanation:
The investigation of electricity, gravity of earth and structure of atom helps the student to understand that without touching, one object apply force on another object. In electric current, we can see the property of magnetism due to which it attract and repel objects while in gravity of earth, the earth apply gravitational force to attract objects towards itself. in the structure of atom, proton present in the nucleus which attract the electron present in the shells.
