Answer:
B) The completely-plated phenotype is controlled by a dominant allele of a single gene.
Explanation:
<em>The results from the breeding experiment showed that the completely-plated phenotype is controlled by a dominant allele of a single gene because it followed Mendelian pattern of inheritance.</em>
According to Mendel, in a dominant/recessive gene situation, the recessive gene do not manifest physically in F1 generation and at F2, the phenotypic ratio of dominant to recessive gene is usually 3:1.
For example, assuming the completely-plated gene is represented by P and the alternate form (low-plated) by p.
At F1: PP x pp
Progeny: all Pp, completely-plated stickleback in appearance.
At F2: Pp x Pp
Progeny: PP, Pp, Pp, and pp
3/4 of the progeny have completely-plated appearance while 1/4 have low-plated appearance. The ratio of completely-plated to low-plated is 3:1.
The correct option is B.
<span>Mendel showed that the green-seed trait did not disappear but was only masked by breeding plants with only two alleles for the trait. After the cross of yellow seed, a small amount of offspring had green seeds. So, he concluded that the green-seed trait is masked by the dominant yellow-seed trait and that two alleles are necessary for green-seed trait to show up.</span>
C is for question 1 and 2
Answer:
Two gametes end up with 30 chromosomes, one gamete will have 31 and one will have 29.
Explanation:
During meiosis, a single diploid cell divides into four haploid cells with half the chromosome number than the parent cell.
During meiosis I, homologous chromosomes separate and the chromosome number in the two daughter cells goes down by half. During meiosis II, the "sister" chromatids separate, and the chromosome number in the respective daughter cells remains the same.
Non-disjunction of a single dyad in meiosis II causes that one of the daughter cells will have an extra chromosome, and another will be lacking one. The two other gametes will be normal.
I drew a simple example of what would happen during meiosis of a 2n=4 cell if there was non-disjunction in a single dyad during meiosis II.
