Answer: is heterozygous
Explanation: A hybrid is heterozygous which means that it has one dominant gene and one recessive gene. A dominant gene is a type of gene which has the ability to express itself phenotypically either in a homozygous or a heterozygous state. A dominant gene masks the effect of a recessive gene. A recessive gene is a type of gene that lacks the ability to express itself in a heterozygous state. It can only express itself outwardly in a homozygous state. It's effect is masked by the dominant gene is a heterozygous state.
Chemical factors: This is due to internal stimuli. Changes in the blood such as decrease in O2, increase in CO2 and decrease in PH cause impulse in the carotid artery which stimulates the respiratory centers in the medulla and cause breathing.
Mechanical factors: also called external stimuli. Compression of the fetal chest during delivery forces small amount of lung fluid out of the lungs. This increase in pressure in the chest draws air into the lungs.
