Question

When a tall homozygous plant was crossed with a short homozygous plant, the F1 offspring were all tall. No short plants were present in the F1 generation. Which principle does this situation represent?



A.The principle of unit characters



B.The principle of dominance



C.The principle of segregation

Answer 1

The principle of unit characters states that certain aspects of an organism (height, color etc) are dictated by "units" (These were later known as genes.

The principle of segregation states that cells contain of pair of these units (genes), and that their gametes will only have one unit from each pair.

The principle of dominance states that a dominant gene will always show, whether in a heterozygous or homozygous organism. and a recessive gene can only show when the dominant gene is absent in a homozygous organism.

As both plants were homozygous, (and their offspring only exhibited the height of the tall parent) you can deduce that the tall plant had dominant genes, and the small plant had recessive genes. Thus exhibiting the principle of dominance.