The homologous chromosomes appear to repel each other and partially separate. Each chromosome is now seen to be composed of two chromatids. The two chromosomes are joined at several points along their lengths. these points are called chiasmata. This occurs as a result of breakage and reunion between any two of the four strands present at each site. Thus resulting in the swaping of genes from one chromosomes (paternal) with genes from the other chromosomes (maternal) leading to new gene combination in the resulting chromatids.
Buoyancy The density of fresh water is considerably less than that of the sea and such floatation is a greater problem for fresh water plankton. There is occasional flooding which submerges the plants. The water lilies, water lettuce, water hyacinth are able to stay afloat because of the air spaces in the lower part of the leaves as well as in the skins and roots.
Comments
Post a Comment