If someone has a dominant phenotype, their genotype can either be heterozygous or homozygous. The diagram shows a Punnett square for a particular trait among two parents, but one letter of a parent’s genotype is missing.

Which describes the letter that belongs where the question mark is?

T because there are offspring that are heterozygous
T because there are offspring that are homozygous
t because there are offspring that are homozygous.
t because there are offspring that are heterozygous

What is the difference between the conducting zone and the respiratory zone of the respiratory system? the conducting zone is a series of cavities and tubes that move air to the respiratory zone where gases exchange with the bloodstream. the conducting zone exchanges gases between the lungs and the alveoli and the respiratory zone is a series of cavities and tubes that move air to the conducting zone. the conducting zone moves oxygen into the cells and the respiratory zone takes carbon dioxide away from the cells. the conducting zone moves oxygen into the bloodstream and the respiratory zone takes carbon dioxide away from the bloodstream.