In multicellular organisms, the process of cell division leads to in the cell number

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

How have high taxes on tobacco products impacted the number of people who use them? a. the number of tobacco users has increased. b. the number of tobacco users has decreased. c. the number of tobacco users has not changed. d. the number of adolescent tobacco users decreased, while the number of adult users increased

Why has two different alleles for the same trait?