Organisms that inhabit intertidal zones must be able to tolerate radical changes in temperature, salinity, and moisture and also be able to withstand wave shock. Intertidal zone is the coastal area alternately exposed and submerged by tides. Tide pool animals and plants are well adapted to the intertidal zones. Some adaptations include; the ochre sea star can tolerate a longer time period exposed to air than many other sea stars. They regularly withstand up to eight hours of exposure during low tides.
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.
The centrioles help in the information of the spindle fibers that separate the chromosomes during cell division.
