To maintain a line of pure-breeding peas, selective breeders would use a technique called artificial cross-pollination. This is a technique were breeders transfer pollen from the anthers of one pea plant (male parent) to a stigma of a flower (female parent).
This technique was developed by Gregor Mendel, the founder of the science of genetics. He was a monk who dedicated his time in research about how genes of plants are carried over through specific species. In his controlled experiment he used the pea plant because they are cheap and readily available from merchants who sold them in different classifications. He also used pea plants because they have the capacity to self-pollinate or cross-pollinate.
Basically his experiments, which scientists came to know only after he was dead. His experiments, and of course, the result of this experiments that served as a proof of what Mendel afirmed, where one of the most importnat factors that made his ideas accepted.
They where also accepted because he discovered DNA, the basic laws of inheritance and chromossomes.
Hope it helped,
Happy homework/ study/ exam!
A housekeeper I think , that's the answer
While there is no graph provided and I cannot find the graph online, I will base my answer through theory.
In theory, the most common blood type is O+, followed by A+, then B+, then AB+. Rh negative blood is deemed to be rare. While the most common blood type is O+, the same blood type is also called the "universal donor" as a type O+ blood has no antigens attached in red blood cells therefore the probability of adverse reactions (i.e. hemolytic reactions) when transfused to other blood types are close to nil. In an emergency situation, wherein there is not enough time to do proper crossmatching, blood type O+ can be used therefore supplies of blood type O+ are easily depleted.
