Describe how meiosis provides for genetic variability. If an animal had a haploid number of two (no sex chromosomes), how many genetically different gametes could it produce? (Assume no crossing over.) What if it had a haploid number of five?

Meiosis is a type of cell division that produces four gametes, or sex cells, with half the number of chromosomes as the parent cell (referred to as haploid cells). Meiosis is crucial for sexual reproduction and introduces genetic variability through two key processes: independent assortment of chromosomes and, if allowed, crossing over between homologous chromosomes. In this exercise, we are only considering independent assortment as a source of genetic variability. Independent assortment occurs during meiosis I when the paired homologous chromosomes line up along the metaphase plate, and their orientation is random. This means each gamete produced can have a different combination of maternal and paternal chromosomes.

By assuming no sex chromosomes and no crossing over, we can use the independent assortment principle to determine the possible number of genetically different gametes. For an animal with a haploid number of two chromosomes (n=2), there are two pairs of homologous chromosomes. The different combinations can be calculated using the formula: \(2^n\) where n is the haploid number In this case, \(2^2 = 4\) So, the animal with a haploid number of two can produce 4 genetically different gametes.

Now, let's calculate for an animal with a haploid number of five chromosomes (n=5), assuming no sex chromosomes and no crossing over. Using the same formula: \(2^n\) In this case, \(2^5 = 32\) So, the animal with a haploid number of five can produce 32 genetically different gametes. In conclusion, meiosis contributes to genetic variability in organisms mainly through independent assortment of chromosomes and crossing over (though not considered in this exercise). An animal with a haploid number of two can produce 4 genetically different gametes, while one with a haploid number of five can produce 32 genetically different gametes.