The answer is;
The rift valley formed when the crust pulled apart.
The rift valley formed at a divergent boundary.
Divergent boundaries occur when two adjacent convection currents in the mantle are spinning in opposite directions. This causes the upper crust to stretch creating tension due to drag in different directions on the local region. The tension causes the crust to crack severally and the middle crust block dropping in comparison to flanking regions.
Answer:
D
Explanation:
Looks correct if you go with D
Answer:
The final product is four gametes, two of them with 5 chromosomes, and the other two with 3 chromosomes each.
Explanation:
If nondisjunction occurs during meiosis 1, a pair of homologous chromosomes fail to separate, and one of the daughter cells will have the two chromosomes while the other cell will not get any chromosome from the pair.
If meiosis 1 occurs normally, but nondisjunction occurs in meiosis 2, sister chromatids fail to separate.
The usual process of meiosis produces four daughter haploid cells (n) from a diploid germ cell (2n). Each daughter cell is haploid because they have half the number of chromosomes of the original one.
If the diploid number of the original cell is 8 (2n=8), then under normal conditions, each haploid daughter cell should have 4 chromosomes (n = 4).
But in the exposed example, one pair of homologous chromosomes experiences nondisjunction during meiosis I (in the attached file, you will recognize this pair as the red one). The other chromosomes separate as usual. So one of the daughter cells will have one extra chromosome than expected (five instead of four), and the other daughter cell will lack one chromosome (three instead of four). Meiosis II occurs normally. The final result is the formation of four gametes, two of them with 5 chromosomes, and the other two with 3 chromosomes each.
In the block to polyspermy, entry of the sperm's contents causes calcium ion levels in the oocyte's cytoplasm to rise, triggering the cortical reaction.
In biology, polyspermy describes the fertilization of an egg by more than one sperm. Diploid organisms normally contain two copies of each chromosome, one from each parent.
The cell resulting from polyspermy, on the other hand, contains three or more copies of each chromosome—one from the egg and one each from multiple sperm. Usually, the result is an unviable zygote. This may occur because sperm are too efficient at reaching and fertilizing eggs due to the selective pressures of sperm competition.
The cortical reaction is a calcium-dependent exocytotic process in which the content of secretory granules is released into the perivitellin space immediately after fertilization, which serves to prevent polyspermic fertilization.
Learn more about polyspermy here : brainly.com/question/4537960
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