The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus.

TLS Online TPP Program

#Id: 7041

#Unit 11. Evolution and Behavior

 Natural selection was Darwin’s brilliant hypothesis, independently conceived by Wallace, that accounts for adaptations, features that appear “designed” to fit organisms to their environment.

TLS Online TPP Program

#Id: 7042

#Unit 11. Evolution and Behavior

TLS Online TPP Program

#Id: 7043

#Unit 11. Evolution and Behavior

Where, though, do these hereditary variations come from? This was the great gap in Darwin’s theory, and he never filled it.

TLS Online TPP Program

#Id: 7044

#Unit 11. Evolution and Behavior

Orthogenesis - “Straight-line evolution,” held that the variation that arises is directed toward fixed goals.

TLS Online TPP Program

#Id: 7045

#Unit 11. Evolution and Behavior

 Mutationist - Theories were advanced by some geneticists who observed that discretely different new phenotypes can arise by a process of mutation.

TLS Online TPP Program

#Id: 7046

#Unit 11. Evolution and Behavior

Ronald A. Fisher, John B. S. Haldane and Sewall Wright- which showed that mutation and natural selection together cause adaptive evolution.