Answer:
Frequency of the allele "r"causing the disease on Tristan da Cunha
%
Frequency of the allele "r"causing the disease in the original population of 15 colonists 
%
Explanation:
Frequency of the allele "r"causing the disease on Tristan da Cunha
Given -
Out of 240 descendants on the island, 4 had retinitis pigmentosa (rr).
As per Hardy Weinberg's equllibrium equation
The frequecy of recessive individual in a given population is represented by 
And q represents the frequency of allele r
So, in this case q is equal to
%
Frequency of the allele "r"causing the disease in the original population of 15 colonists
As it is given in the question statement , the frequency of allele "r"causing the disease in the original population of 15 colonists is ten times the frequency of the allele "r"causing the disease on Tristan da Cunha
i.e
%
The first one is A
The second one is also A
The third one is also A. So... all A.
Cretaceous extinction also known as Paleogene extinction was a period of time when suddenly around three quarter of the animal and plant species began to get extinct from the land. The event happened around 66 million years ago and is considered as the end of cretaceous era that lead to the beginning of Mesozoic era.
Reasons for the mass extinction:
- Scientists think that a major asteroid or comet hit the surface of earth which deteriorated the earth’s environment, especially by making it difficult for plants to perform the process of photosysnthesis. This is called as Impact hypothesis and scientists think that it was the reason of extinction of so many species because they found debris of asteroid in the land.
- There could also be some other reasons like climate changes,volcanic eruptions and changes in the sea level which made the environment unfavorable for the survival of living organisms.
- One of the best known organism that is thought to extinct in cretaceous period was dinosaur.
Extinction of Dinosaurs:
As stated above the exact cause of dinosaur extinction can not be stated with confidence. This is because cretaceous period was the time when so many unfavorable circumstances took place like diseases, geologic events ,climate change etc.
However, the most believed theory is that some Asteroid hit the surface of earth and turned the climate very very old. Therefore, those amazing creatures were not able to survive that climate.
Hope it help!
Answer:
they have to remain small because nutrients go around faster around the cell then bigger cells
Explanation:
hopefully i explained it well
