What is the mutation caused by the addition of a nucleotide to an already existing gene sequence called?

Insertion

Explanation:

Insertion is where one or more nucleotides are added to a DNA sequence.

Insertions can be hazardous if they occur in the exonic (amino acid coding) regions of the genome.

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.

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ι нσρє тнαт ι ¢συℓ∂ нєℓρ уσυ.