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The answer is
1) Valves between atria and ventricles close, 2) first heart sound heard, 3) valves between ventricles and body close, 4) second heart sound heard
Answer:
Silent mutations are mutations in DNA that do not have an observable effect on the organism's phenotype. They are a specific type of neutral mutation. The phrase silent mutation is often used interchangeably with the phrase synonymous mutation; however, synonymous mutations are not always silent, nor vice versa.