Question

1) What is the effect of crossing over in the gametes? What is its effect in the next generation?

2) How would nondisjunction be different if it occurred in anaphase II? Draw the results of nondisjunction in anaphase II for a cell that starts meiosis with four chromosomes.

3) Using the 40X lens, focus on the cells within the pollen sacs in late prophase. Draw a cell in late prophase. Describe any differences from the early prophase slide.

4) Use the 5X lens to observe cells in late prophase. Note that some of our slides show sections of single pollen sacs, not whole anthers.

Answer 1

Crossing over or the recombination is the process in which transfer or the exchange of genetic material takes place between 2 homologous chromosome . Homologous chromosome are the chromosome that have same structure same size and location of the genes are also identical at the same Place crossing over or the recombination occurs in the pachytene stage of the meiosis 1 . During the exchange of genetic material between the father and the mother's chromosome . Genes are transferred and the new combination of gene are formed then these genes are incorporated into the gametes leading to new combination of genes . The effect of crossing over or the recombination seen in the form of variation . As seen in the variation these variation when accumulated over number of generation leading to the genration of new character or trait . Crossing over is one of the cause of mutation and plays an important role in the evolution process .

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