What is the factor called that cannot express its effect in the presence of another factor?

Some individuals with blood group $A$ may inherit the genes for blonde hair, while other individuals with blood group $A$ may inherit the gene for brown hair. This can be best explained by the principle of

Which of the following laws was discovered first by Mendel?

Which one of the following is not matched with Mendel's Law of Dominance?

Mendel's principle of segregation means that the germ cells always receive

What does the Law of Segregation represent?