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.
Hey there!
The skin and nervous tissues develop from the ectoderm.
During the examination of a patient suffering with a lung or respiratory disease, a nurse is expected to hear different types of sounds coming from different parts of the lungs. The sound can be crackled, broken, high-pitched, medium-pitched, etc.
A nurse is expected to hear a bronchovesicular lung sound NEAR THE STERNAL BORDER in a healthy adult.
Mitosis - Asexual, diploid, 1, 2, during the synthesis phase.
Meiosis- sexual, haploid, 2, 4, during the synthesis phase.
Cytokinesis is the process wherein actual division of the cell, including the cell membrane and the cytoplasm, from the parent cell to two daughter cells. The correct answer in this question is "the metaphase plate is the beginning area for cytokinesis" as the metaphase plate dictates the midpoint of the cell. A cell with a cell wall (plant cell, for example) cannot perform cytokinesis with a cleavage furrow but with a cell plate. Phragmoplast only develops in plant cells. Lastly, cytokinesis only starts after telophase.
