Seeds from a diploid true breeding plant that produces purple flowers were mutagenized. Below are the genotypes and phenotypes of plants generated from this mutagenesis experiment. Assume that the wild-type alleles (uppercase) are dominant to mutant alleles (lower case) and the two genes are not linked. Genotype Flower color A_B_ Purple aaB_ Orange

The Answer is B

Explanation

abb genotype produces brown pigment. In this case mutant alleles are present at both the locus and brown pigment is produced which suggest the brown pigment is the precursor for the pathway and is present even when both mutant alleles are present.

aaB_ genotype produces orange pigment which suggest that B allele is responsible for conversion of brown pigment to orange pigment. This is also supported by the genotype A_bb which produces brown pigment because wildtype B allele is not present. A allele cannot convert Brown to orange, therefore flower colour is brown.

A_B_genotype produces purple pigment which suggest both A and B allele are responsible for conversion of brown pigment to purple pigment

fertilization, pictured in figure 24.23a is the process in which gametes (an egg and sperm) fuse to form a zygote. the egg and sperm each contain one set of chromosomes. to ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. in mammals, the egg is protected by a layer of extracellular matrix consisting mainly of glycoproteins called the zona pellucida. when a sperm binds to the zona pellucida, a series of biochemical events, called the acrosomal reactions, take place. in placental mammals, the acrosome contains digestive enzymes that initiate the degradation of the glycoprotein matrix protecting the egg and allowing the sperm plasma membrane to fuse with the egg plasma membrane, as illustrated in figure 24.23b. the fusion of these two membranes creates an opening through which the sperm nucleus is transferred into the ovum. the nuclear membranes of the egg and sperm break down and the two haploid genomes condense to form a diploid genome.

explanation:

4tghyjuklertghyjukl