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Free earlobes hang below the point where the ear lobe attaches to the head. Attached earlobes do not hang, but are attached to the head. The gene for free earlobes is dominant (F), while the gene for attached earlobes is recessive (f). Both of Ashley’s parents have free earlobes but also carry a recessive gene for attached earlobes. Ashley has attached earlobes, so she must have A) one dominant gene for free earlobes. B) two dominant genes for free earlobes. C) one recessive gene for attached earlobes. D) two recessive genes for attached earlobes

Respuesta :

D. Two recessive genes

Answer: Two recessive genes for attached earlobes.

Explanation :

Since both of Ashley's parents have free earlobes but carry a recessive gene as well, they must be heterozygotes and hence their genotype would be Ff.

When they mate the cross would be as follows :

Ff X Ff----> FF Ff Ff ff

The phenotype of

1. FF and Ff ---> Free earlobes

2. ff ---> attached earlobes

Since Ashley has attached earlobes, her genotype must be ff this implies that she has two recessive genes for attached earlobes.

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