Answer:
4. Green
5. 1 Green : 1 Blue parakeet
6. 100% green offsprings
7. Violet color
8. 0%
9. 1 Yellow : 1 white sulfur butterflies
Explanation:
4. A dominant trait is that which masks the phenotypic expression of its contrasting trait in a gene. Hence, the cross between a green and blue parakeet produced offsprings that were all green because the green trait is dominant i.e. mask the expression of the blue trait.
5. An heterozygous green parakeet will have genotype:Gg while a homozgous blue parakeet will have genotype: gg. A cross between Gg and gg will produce offsprings with genotypes: Gg and gg in the proportion 2:2. This means the phenotypic ratio of Gg (green) and gg (blue) is 1:1.
6. A homozygous dominant parakeet means genotype, GG while a heterozygous green parakeet means genotype, Gg. GG and Gg, if crossed will produce offsprings with genotypes: GG, GG, Gg and Gg. Since the allele for green color (G) is dominant over the allele for blue color (g), all the offsprings i.e 100% will be green colored.
7. A purebred flower means a flower that produces only one type of color and is homozygous. Hence, let's say a purebred red flower will have genotype RR while a purebred violet flower will have genotype VV. Hence, these two purebreds will be crossed to produce offsprings that all possess genotype, VR. According to the question, they are all violet. This means that the allele for Violet color is masking the phenotypic expression of the red color. Hence, the Violet color is a dominant trait.
8. A homozygous Violet and red flower will have the genotypes: VV and RR respectively. A cross between them will produce an offspring with genotype, VR. Since the Violet allele is dominant, it will be phenotypically expressed over the red allele. Hence, none of the offsprings i.e. 0% will be red-colored.
9. A heterozygous sulfur butterfly will be Yy while a homozygous recessive sulfur butterfly will be yy. Where Y is yellow allele and y is white allele. If Yy and yy are crossed, offsprings with genotypes Yy and yy will be produced in the ratio 1:1. This means that the phenotypic ratio of the cross between a heterozygous sulfur butterfly (Yy) and a homozygous recessive sulfur butterfly (yy) is 1 Yellow sulfur butterfly: 1 white sulfur butterfly.
