Aproximately 30% of substitution mutations result in no change in the genetic code, why?

1. A mutation that causes changes in the amino acid sequence downstream of the mutation is called FRAME SHIFT MUTATION. The correct option is D. A frame shift mutation is one in which the mutation is caused either by the addition or deletion of base pairs in the DNA of a gene, this results in the translation of the genetic code in the wrong reading frame starting from the position of the mutation to the end of the affected gene. Frame shift mutation result in the production of nucleotide that are not divisible by three. Because the nucleotide codons are usually pair in three, frame shift mutation causes a change in the reading frame and this result in a protein translation that is different from the original.

2. The correct option is D.

If the third base A is deleted from the codon given in the question, it will results in the formation of frame shift mutation and this will change the translation of the protein from leucine to tyrosine. The deletion will not affect the first amino acid in the sequence.

3. Albinism is a type of mutation that can is described as DELETERIOUS. The correct option is D.

Deleterious mutation refers to any type of mutation which reduces the fitness of a living organism. Albinism is a medical condition in which an individual experience a partial or total loss of skin pigmentation. The condition is a genetic disorder that is caused by lack of adequate amount of melanin pigment in the skin. Albinism causes vision loss, extreme sun sensitivity and stigma.

4. The type of mutation that occur is INSERTION. The correct option is B. Insertion is a type of mutation in which one or more nucleotide base pairs are added to a DNA sequence. The inserted base pairs can be small or large. Examples of disease conditions that resulted from insertion mutation are Huntington's disease and fragile X syndrome.

of those who start drinking before they're 15 will develop alcohol dependence

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.