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Fed [463]
2 years ago
7

Knowing that some individuals from Island 1 colonized Island 2, biologists sample the Mainland and two Island populations fifty

years after the colonization events. They determine that allele frequencies are similar on both islands, but they are significantly different than the frequencies of the mainland population. Which of the evolutionary mechanisms could be used to explain these observed
Biology
1 answer:
raketka [301]2 years ago
5 0

Answer:

The evolutionary mechanism that could be influencing the allele frequencies between both islands and the mainland population might be Founder Effect.

Explanation:

Genetic drift is the random change that occurs in the allelic frequency of a population through generations. The magnitude of this change is inversely related to the size of the original population. These changes produced by genetic drift accumulate in time and eventually, some alleles get lost, while some others might set. Genetic drift affects a population and reduces its size dramatically due to a disaster -bottleneck effect- or because of a population split -founder effect-. In <u>founder effect</u>, a new population originates when a few individuals who are coming from a bigger population carrying its genes, settle down in a new area and reproduce. This small population might or might not be genetically representative of the original one. Some rare alleles might be exceeded or might be completely lost. Consequently, when the small population increases in size, it will have a genetically different composition from the original one. In these situations, <u>genetic variability is reduced</u> and there exists the possibility of developing a peculiar allelic composition. If the number of individuals that originated the new population is low, the founder effect will be very extreme, because the effects of the genetic drift are inversely proportional to the original number of individuals.  

<em>In the exposed situation, the evolutionary mechanism that could be influencing the allele frequencies between both islands and the mainland population might be Founder Effect. The fact that both islands are similar in their frequencies might be due to little genetic variation on island 1, or because dispersion to island 2 is a recent event on time. </em>

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Your lab group is experimenting with the diffusion of molecules across a membrane. Dialysis tubing is used as a model cell membr
Margaret [11]

Answer: the membrane channel

Explanation:

In passive diffusion, the small water molecules can move across the phospholipid bilayer seen in blue. This layer acts as a semi-permeable or selectively permeable membrane; its hydrophilic heads are attracted to water (seen facing outwards) while its water-repellent hydrophobic tails face towards each other- allowing  molecules of water to diffuse across the membrane along the concentration gradient.

Thus the water will move from an area of high concentration  to an area of low concentration, until the system reaches a steady state called equilibrium- after this, there will be no net movement of water. Similarly via osmosis, the water passes through the membrane due to the difference in osmotic pressure on either side of the phospholipid bilayer this means that the water moves from regions of high osmotic pressure/concentration to regions of low pressure/ concentration to a steady state.

The dialysis tubing mimics a semi permeable membrane; it only allows water and small molecules of iodine to cross into the bag containing starch. The tubing is impermeable to starch;  these large molecules require the aid of protein omplexes called membrane channels, in order to move across the membrane and against the concentration gradient.

5 0
3 years ago
As children get older, cultural influences on behavior become much stronger; and as a result, it becomes difficult, if not impos
DanielleElmas [232]

Answer:

False

Explanation:

Sex is a biological term and gender is depended on the roles performed by an individual. In our society it is mandatory for a man or woman to behave and develop sexual preference for its opposite gender and this conservative thought process had strongly held the base of defining a sexual acts which is intended to happen between a male and female only.

However, this is not something defined by nature but by individual likeliness. This is the reason why even after being a male by sex, a male by gender can have likeliness for another male. This is something which cannot be bounded by social and cultural belief even after being into it for years.

Hence, the given statement is false

3 0
3 years ago
In coccidioidomycosis, _______ containing many endospores form in the lungs.
dolphi86 [110]

Answer:

spherules

Explanation:

Like histoplasmosis, coccidioidomycosis is acquired by the inhaling fungal spores.

<u>Arthrospores are formed by the hyphal fragmentation in this case. Once in body, fungus differentiates into the spherules which are filled with the endospores. </u>

Most of the C. immitis infections are self-limiting and asymptomati. The endospores are transported in blood, disseminating infection and thus leading to formation of granulomatous lesions on face and nose. I

<u>Thus, spherule is a thick-walled spherical structure which encloses the endospores and occurring in parasitic form of the fungi of genus Coccidioides.</u>

7 0
3 years ago
Which of the following is true of the blood-brain barrier? a. The barrier is formed by cells that line the capillaries of the br
grin007 [14]

Answer:

The barrier functions to regulate the chemical composition of the extracellular fluid surrounding the brain cells.

Explanation:

Blood-brain barrier

It is a very selective semipermeable membrane , hence allow some specific substance to pass via it . This barrier separates the  extracellular fluid in the central nervous system  and the circulating blood from the brain .

<u>The barrier is composed of the endothelial cells .</u>

Passive diffusion is shown in this system , and allows molecules like the water , glucose , amino acid to pass .

It regulates the chemical composition of the fluid of brain cell .

6 0
3 years ago
Which word describes the amount of matter an object contains?
Brrunno [24]
MASS: because it is the measure of the amount of matter in an object
4 0
2 years ago
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