<h3>Global travel and spread of certain species</h3>
Explanation:
Many pathogenic species of bacteria, virus, and other microbes are more prevalent in developing or tropical countries rather than in developed countries.
When an individual’s immune system is weak they become more susceptible to get infected and become carriers of that particular species.
The species grows, develops, and multiplies in the host’s body and when the traveler travels to his/her home country or any other place he/she can transmit the disease to others and again the species grows in numbers. Higher the rate of spread of infection higher is the increase in species.
Answer:
Within the bone marrow, all blood cells originate from a single type of unspecialized cell called a stem cell. When a stem cell divides, it first becomes an immature red blood cell, white blood cell, or platelet-producing cell.
Explanation:
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