Why doesn't the substitution of nucleotides in the mouse change its phenotype or physical charateristictis?

Light sensitivity in euglena is provided by the

Iwill mark which of these statements best describes how nasa's kennedy space center benefits florida? it improve the average income of people. it encourages the use of science for entertainment. it produce more astronauts and space scientists in florida. it encourages people in florida to use space technology in homes.

Idon’t understand this can someone give me the answer? you