A manifestation of local blood flow regulation.
During the cell cycle, the centrioles are made during interphase. The centrioles move to opposite sides of the cell and spindle fibers form a bridge between them during prophase, which is one stage out of the four stages in mitosis.
It helps get rid of carbon dioxide.
Took me a while to understand any of this XD
Answer:
The correct answer is b. must be present in a population before natural selection can act upon the population
Explanation:
Genetic variation can be caused by mutation, recombination between chromosomes during meiosis and by fusion of two genetically different gametes during sexual reproduction.
This genetic variation is necessary for the evolution of any population. Natural selection acts on every individual and it decreases the frequency of those alleles that are not suited for the environment and increase the frequency of those alleles which helps the individual to survive in the changing environment.
Therefore genetic variation must be present in the population before natural selection act on the.
