Edexcel IGCSE Biology 3.36B mutation effects on phenotype

Practise using codon tables and mutation evidence to explain why DNA changes may not alter proteins, enzymes or phenotype.

Exam points

interpret a codon table to show that different triplets can code for the same amino acid
explain why unchanged amino acid sequence means no change in protein, enzyme or phenotype
link phenotype effects to whether the protein shape or active site is changed

[Maximum number: 3]

The sequence of bases on one strand of a section of DNA is

TAC CGT AAT TAT

The table shows different mRNA codons for some amino acids.

Table for Question 3.36B Effects of genetic mutations question 1 — Edexcel IGCSE Biology

Explain why most genetic mutations have no effect on the phenotype of an organism.

Use the information in the table and your own knowledge in your answer.

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3.36B Effects of genetic mutations question 1