What is the maximum amount of time perishable foods can safely be held in the danger zone?

The maximum amount of time that the perishable food can be safely held in danger zones is two hours. More than two hours could cause the food to be contaminated or spoiled, which is not safe for an individual to cook or consume for it could cause food poisoning.

they are known to reach a speed of 21 miles per hour

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.

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