The chromosomal mutation in the zygote can be traced back to "Chromosome 6 in the egg cell".
<u>Option: B</u>
<u>Explanation:</u>
In germ cells i.e. egg or sperm cells, the mutations in chromosome often happen during the meiosis phase. The number of chromosomes in egg cells or sperm cells must be haploid, so that diploid chromosomes form zygote on fertilization. Chromosome mutation in meiosis leads in an additional set of chromosomes or structural defects in the chromosome.
Chromosomal mutations are often caused by chemical agents or by mutagens.
The homologous chromosomes are segregated from sister chromatids throughout cell division, any abnormality at this point allows the chromosomes to be unequally divided or not disjuncted, same is observed in the situation seen in egg cell chromosome 6.
 
        
             
        
        
        
ALL organic compounds ALWAYS contain carbon!!
 
        
                    
             
        
        
        
Zambia
The other three are already well established.
        
             
        
        
        
Answer:
a.The phenotypic proportions obtained after having the genotypes are 50% marbled seeds, 25% spotted and dotted seeds since they are codominant, 25% spotted seeds.
b. Taking into account the F1 genotypes in the previous point, the expected phenotypes for the first crossing are 100% marbled seeds and for the second crossing 100% dotted seeds.
Explanation:
Let's suppose:
Marbled allele: M
Spotted allele: S
Dotted allele: D
Allele for Clear: C
a. Because both crosses were between homozygous parents, the entire F1 genotype is the same. 
For the first crossing the descendants have the MS genotype, and for the second crossing the descendants have the DC genotype. It is enough to make a Punnett square to obtain the different combinations of genotypes between the crossing of MS and DC.