During the menstrual phase of the menstrual cycle, the zona pellucida develops around each egg.
The menstrual cycle is count from the first day of one period to the first day of the next period. The menstrual cycle differs in all women. This cycle has four main phases namely the follicular phase, ovulation phase, luteal phase and the menstrual phase.
The follicular phase starts on day one. The follicle stimulating hormone or FSH and estrogen rise. This is followed by the ovulation phase in which the egg is released. In the luteal phase corpus luteum produces progesterone and estrogen. In the menstrual phase of the menstrual cycle, the zona pellucida develops around each egg.
To learn more about menstrual cycle here
brainly.com/question/27471285
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Explanation:
The problem says that the hairless phenotype never breeds true. That means that it's not the result of a homozygous genotype (H₁H₁ or H₂H₂), so it is caused by the heterozygous genotype (H₁H₂).
The <u>expected </u>offspring from the cross between two Mexican hairless would be:
<h3>P
H₁H₂ x
H₁H₂</h3><h3>F1 1/4
H₁H₁, 2/4
H₁H₂ and 1/4
H₂H₂.</h3>
And the <u>expected</u> phenotypic ratio 3:1. However, the observed offspring shows a 2:1 ratio. What's happening?
If the observed phenotypic ratio in the offspring of a monohybrid cross (a single gene with two alleles) is 2:1, we can suspect that one of the genotypes is lethal in homozygosis and therefore does not appear in the progeny (the puppies are born dead).
If we proposed that the H₂ allele is lethal in homozygosis, then:
- The H₁H₁ genotype would cause normal puppies --> 1
- The H₁H₂ genotype would cause hairless puppies --> 2
- The H₂H₂ is lethal and causes the death of puppies --> 0
The phenotypic ratios change to 2:1, as observed in the experiment.
I believe its your heart if I am not mistaken hope this helps ^^;
