Question

8) Giardin has two haploid nuclei that are not 100% identical. This is a major odd ball in eukaryotes. What does that observation suggest? A) All nuclei are derived from a single ancestral cell B) Diploid nuclei have more evolutionary advantages than two haploid nuclei C) Asexual reproduction requires two haploid nuclei D) Giardia's two nuclei came from two different bacterial endosymbiotic events 9) Asexual reproduction in eukaryotes is unusual. Many eukaryotes can do asexual and sexual reproduction but not Giradia. What does this suggest about sex in the eukaryotic domain? A) sex is lacking in some eukaryotes that diverged from the early common ancestors of other extant eukaryotes B) sex was a characteristic of Giardin but it lost the ability C) horizontal gene transfer is the only way Giardia has survived for 500my D) antibiotics must have selected for asexual pathogens

Answer 1

Okay, let's describe a bit Giardia's life cycle, ploidy and reproduction. This organism has two genome copies like any diploid eukaryote but it is not a 2n nucleus, but two haploid nuclei. When it is time to reproduce, it undergoes asexual binary fission. Now, for the questions. I recommend to always analyse every single option and evaluate if there's any truth in them related to the stated question.

8.- D) Diploid nuclei have more evolutionary advantages than two haploid nuclei. That is because a diploid nuclei can undergo recombination, which is the process that Giardia undergo when in cyst, they fuse the haploid nuclei and undergo recombination, then again separate in two haploid nuclei

9.- B) Sex was a characteristic of Giardia but it lost the ability. Sexual reproduction is one important characteristic of eukaryotes, and since Giardia shows very wierd genomic treats, and parasitic species tend to undergo strong changes to facilitate life in the host. The loss of sexual reproduction ability has a high probability.