Answer:
include the brain and spinal cord
Explanation:
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.
Answer:
Nucleus is the structure present in the cells that directs the cell activities.
Explanation:
Nucleus is responsible for cell division also it has heredity material stored inside it in the form of DNA.
It also plays a very important role in the synthesis of particular enzymes as well.
Gametes such as sperm and egg cells have haploid numbers of chromosomes until the moment of fertilization.
The answer is D) All of the above
