Homologous chromosomes pair up and exchange segments of DNA.
Option A
<h3><u>Explanation:</u></h3>
Crossing over is an event of Prophase 1 of meiosis 1. It occurs in the zygotene phase of prophase 1. Here the homologous chromosome pairs get very close together and gets packed within protein coat. The enzymes randomly cut the DNA segments from both chromosomes at same loci and exchange them with each other. This results in the exchange of genes between the two chromosomes. This is how the variation comes to place between offsprings of the same individuals. The crossing over results to form X shaped intersections between homologous pair of chromosomes which is called as chaismata. This phase occurs in pachytene phase and is visible in diplotene phase when the protein coat dissolves.
C) a lack of comeption hope I helped.
Answer:
The oceans are present on the 70 percent of the world but only 5 percent of the total oceans are explored yet.
There are many reasons of this problem but the most important is the hydrostatic pressure.
Hydrostatic pressure can be described as the pressure or weight exerted by the water on the object.
With every increase in 10 meters the pressure increase by 6.47kg (14.27lbs) each square inch of surface.
Due to extreme pressure, oxygen level in the cells of body fluctuates and person becomes unstable and can become unconscious.
Explanation:
most copy the chromosomes first and then carefully separating the copies to give each new cell a full set
