Meiosis #1

Which of the following are advantages for animals that reproduce sexually?

Select ALL that apply.

• Offspring are genetically identical to the parent.

• Sexual reproduction involves mitosis exclusively.

• Deleterious (bad) alleles are weeded out by natural selection.

• Re-shuffling of genes occurs during gamete formation and fertilization.

• Two parents of the opposite sex are needed.

Which of the following is a source of variation in populations?

Select all that apply.

• Independent assortment of chromosomes

• crossover in meiosis

• random fertilization

Which of the following is NOT a source of genetic variation?

• Crossing-over during meiosis

• Errors that occur in DNA replication

• Replication of cells through mitosis

• Environmental factors that cause mutations of genes.

How is the process of independent assortment dependent upon processes such as meiosis and random orientation in order to increase genetic diversity in offspring?

• Independent assortment is not possible until meiosis has separated all four chromatids of the homologous chromosomes after two divisions, then random orientation of these chromatids allows them to assort independently into gametes.

• Meiosis allows for the pairing of maternal and paternal homologous chromosomes so that the resulting gametes are getting a chromosome that is composed of entirely maternal or paternal genetic material.

• Meiosis maintains the diploid chromosome number through the first division, then random orientation of homologues in the second division allows the chromosome number to be reduced to haploid through independent assortment.

• Random orientation ensures that there is no pattern to the alignment of paired maternal and paternal homologous chromosomes in metaphase, allowing for independent assortment of those chromosomes during anaphase.

Yeasts are single-celled eukaryotic organisms. Yeasts undergo mitotic division when conditions are favorable. When limited nutrients are available, yeasts start dividing by the process of meiosis.

What is a likely reason for the change from mitosis to meiosis during reproduction under these conditions?

• The process of meiosis produces greater numbers of yeast cells at a faster rate as compared to mitosis.

• Crossing over of genes during meiosis increases diversity and the chance of survival of the next generation.

• Duplication of genes during meiosis ensures efficient functioning of the newly formed yeast cells.

• The yeast cells formed by meiosis are able to adapt as well as the parent cell because they are identical.