Answer:
Crossing-over between homologous chromosomes (prophase 1), the random lining of homologous chromosomes (metaphase 1), and random fertilization are the mechanisms involved in genetic variation.
Explanation:
Crossing-over between homologous chromosomes (prophase 1), the random lining of homologous chromosomes (metaphase 1), and random fertilization are the mechanisms involved in genetic variation.
The Crossing-over events occur between two homologous chromosomes in the equatorial plane and make the daughter cells genetically different from the original one. The Chiasma is the position where two homologous chromatids interchange genetic information, giving a place for new genetic material or information to be provided to descendants. After crossing over, homologous chromosomes get separated again.
On the equatorial plane, homologous paired together, randomly aline with their kinetochores facing opposite poles. The random arrangement of tetrads is different in every cell going through the meiosis process. There is no equal alinement between two cells. When tetrads aline in the equatorial plane, there is no predetermined order for each of the homologous chromosomes of each tetrad to face one of the poles and then migrate to it while separating. Chromosomes of the homologous pair arrange to face any of the poles to migrate forward to it. Each of the chromosomes has two possibilities for orientation at the plane. When the new haploid cells are formed, the number of variations in each cell is also different and depends on the chromosomes that form that cell. The order in the equatorial plane is what introduces variation into the gametes, being almost impossible for two gametes to have the same genetic charge.
Independent assortment occurs when the alleles from two or more different genes distribute in gametes independently from each other. In other words, a gamete receives an allele from a gene that does not depend on nor influence the allele of another gene in the same gamete. This can only be applied to independent genes. An organism gets only one of the members of the chromatids pair of each parent.
Answer:
10
Explanation:
(6−
6
3
)2−
(4)(3)
2
=(6−2)2−
(4)(3)
2
=42−
(4)(3)
2
=16−
(4)(3)
2
=16−
12
2
=16−6
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Answer:
<h3>The genes that caused scales to become feathers in the early ancestors of birds </h3>
Answer:
Charles Ehler: incorrect.
Wendell Mullison: correct.
Robert Rodriguez: correct.
Judy Johnson:correct.
Explanation:
-Charles Ehler´s statement is incorrect because in order for a chemical company launch a new product it must pass several tests, that´s why products lasts years in proves, there are several tests such as the environment test that proves that the product doesn´t affect other species, or the human safety that makes sure the product doesn´t affect human health.Wendell Mulison´s statement proves to be correct with this as well.
-Robert Rodriguez´s statement is correct because even though there are several tests that take care human healt there are just a few based on the damage pesticides produce to the land where are used.
-Judy Johnson´s statement is correct because science has proved that the resistant of parasites as being increasing with the products tat are used to combat them. Bacterias are an example of it, many drugs used against bacterias are now useless for some people because of the resistantthey have developed.
-One specie that can be taken as a pesticide can be the ground snail, that affects some plants and also may contain a parasite aclled "Hepatic fasciola" that affects sheeps and goats of farmers.
-One viable method to control pesticides is the sue of other species to control them, this specie has to be adequate to the land, for example, if a farmer wants to get rid of the ground snails because of the parasite and the damage they do to their platings, they can introduce ducks to the farm that eat them without damaging the land with any kind of chemical product.
