D) The Earth was hit by a one or more objects from space 65 million years ago. The iridium layer shows an extraterrestrial cause for the extinction at the Cretaceous Tertiary boundary, discovered by the Alvarez family. The first discovery of this layer was in the Bavarian alps, in Lattengebirge. The Alverez family proposed that the extinction of the dinosaurs was due to a large meteor hitting the Earth at the end of the Cretaceous period, marking the KT boundary with this clay layer which has a high content of iridium. Iridium is not common on Earth, but is common in meteors.
It is 200 million years because it has been around for a long time.
I want to say that the best option to go with will be species so option D.
Answer:
You are saying which one but what is which one???
Explanation:
Answer:
25%
Explanation:
When looking at a pedigree remember that:
- squares are males
- circles are females
- the solid colored figure represents an individual affected by a disease
- the empty figure represents a healthy individual
Let us assign the symbol X⁺ to represent the dominant allele linked to the X-chromosome and expressing healthiness, and X⁻ to represent the recessive allele expressing the dissease.
According to this pedigree
- I1 is a man affected by the disease, YX⁻
- I2 is a healthy woman X⁺X⁻
- we can see that among the progeny (generation II) there are two individuals affected (a boy and a girl) and one healthy girl. This means that the mother I2 is heterozygous for the trait.
So, having their genotypes we can know what are the probabilities of getting a son with DMD
Parentals) YX⁻ x X⁺X⁻
Gametes) Y X⁻ X⁺ X⁻
Punnett square)
X⁺ X⁻
X⁻ X⁺X⁻ X⁻X⁻
Y X⁺Y X⁻Y
F1)
- The probabilities of getting a healthy daughter X⁺X⁻ are 25%
- The probabilities of getting a healthy son X⁺Y are 25%
- The probabilities of getting a daughter with DMD X⁻X⁻ are 25%
- The probabilities of getting a son with DMD X⁻Y are 25%
