Francois Jacob and Jacques Monod studied Escherichia coli (E. Coli) bacteria by using lab experimentation. What revision to their initial hypothesis did they come up with? The lac operon is repressed by allolactose. E. Coli are unable to process lactose sugar. All E. Coli operons are always turned on. Two operons regulate gene control in E. Coli.

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation:

age range would be the answer

gag reflex, poor dentition, gum retraction

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