Answer:
It's C. They are mostly made up of hydrogen and helium
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:
There are two types of defense mechanism of plants against herbivorous
1- Mechanical defense
2- Chemical defense
Explanation:
Mechanical defense is a first line defense in which plant makes barriers which is made up of wax cutical and bark and they form spines on leaves, thorns on branches which can helps in resistance and physical damage to animals.
Chemical Defense is a type in which plant produces some metabolites, toxins and chemicals which is very toxic to animals and helps in defense example alkaloids.
Answer:
Basically, when people say that DNA replication is semi-conservative they are saying that two identical copies are being made from the original DNA strand.
Explanation:
The two new strands contain one side of the original DNA and another side of synthesized pair.