Which type of mutation cannot occur in a child after birth?
2 answers:
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Answer:
This question lacks options, the options are:
A) FF and ff
B) FF and Ff
C) Ff and Ff
D) Ff and ff
The answer is D (Ff and ff for parent 1 and 2 respectively)
Explanation:
This question depicts a single gene coding for fur colour in mice. The gene controls two traits, black fur and white fur, encoded by alleles F and f respectively.
According to the question, a pair of mice has been bred several times to generate the same data of 22 black fur and 23 white fur mice. Based on this data, it shows that the phenotypic ratio of black to white mice is 1:1.
To get a 1:1 phenotypic ratio of black fur offspring to white fur offspring, the parents mice must have genotypes Ff (heterozygous) and ff (same recessive alleles).
In a cross between parents Ff × ff (see punnet square), offsprings with the following genotypes will be produced: Ff, Ff, ff and ff. Ff is black furred while ff is white furred.
Ff (2) : ff (2) is equivalent to Ff (1) : ff (1).
Hence, a data of 22 black mice and 23 white mice which represents a 1:1 ratio will only be produced by parents mice with genotypes: Ff and ff.
