Get Genetics Practice 2 Beyond The Basics Answer Key

An organism's genotype is its specific combination of alleles for a given gene. So, for example, in the pea plants above, the possible genotypes for the flower-color gene were red-red, red-white, and white-white. The phenotype is the physical manifestation of an organism's allellic combination (genotype).

In a Punnett square, each potential offspring will receive a gene from both parents and can be expressed as this: GG, GG, Gg, Gg. So as stated above, half of the offspring will be homozygous dominant for the gene (GG), while the other half are likely to be heterozygous dominant (Gg).

So the answer to question 1a is: 0% would have short whiskers. The only way to have short whiskers is to be "ww", and that combo is not possible from the parents in this cross. b) If one parent seal is pure long-whiskered and the other is short-whiskered, what percent of offspring would have short whiskers? ANSWER: 0%.

The genotypic ratio for the cross between a purple radish and a white radish would be 1:1 (Pp:Pp). The phenotypic ratio would be 1:1:0 (purple: white: red). The genotypic ratio for the offspring of a roan cow and a roan bull would be 1:2:1 (RR:Rr:rr). The phenotypic ratio would be 1:2:1 (red: roan: white).

Each pair of alleles represents the genotype of a specific gene. For example, in sweet pea plants, the gene for flower color has two alleles. One allele codes for purple flowers and is represented by the uppercase letter F, whereas the second codes for white flowers and is represented by the lowercase letter f.

When both parents have achondroplasia, their offspring have a 25% chance of having average stature, a 50% chance of having achondroplasia, and a 25% chance of having homozygous achondroplasia (a lethal condition).

Answer and Explanation: The correct answer is a) "no". Because purple is the dominant phenotype, flowers need only one purple allele to appear purple. You cannot tell if the genotype is homozygous for purple or heterozygous.