Question

Scientists have discovered a new, unknown single-celled organism. They decide to compare the DNA sequence of the ubiquitin gene of the unknown organism with classified organisms. The ubiquitin gene is a gene found in some variation in all cells.



Which organism shares the MOST recent common ancestor with the unknown organism?

Question 4 options:

Streptococcus


halophile


green algae


yeast

Answer 1

To determine which organism shares the most recent common ancestor with the unknown organism based on the ubiquitin gene, we would typically look at the evolutionary relationships among the listed organisms (Streptococcus, halophile, green algae, and yeast).

1. **Streptococcus**: A genus of bacteria, which is quite distantly related to single-celled eukaryotes.
2. **Halophile**: This term refers to a type of extremophile organism that thrives in high salt concentrations, often found in archaea. This could be somewhat close if we consider the prokaryotic lineage.
3. **Green Algae**: These are eukaryotic organisms and are relatively close to higher plants. They have a more recent common ancestor with other eukaryotes, including fungi.
4. **Yeast**: This is a type of fungus and is also a eukaryotic organism. Yeast and green algae both belong to the domain Eukarya and share a more recent common ancestor with each other compared to bacteria and archaea.

Given that both the yeast and green algae share a more recent common ancestor in the eukaryotic lineage compared to the bacteria (Streptococcus) and archaeal organisms (halophile), the organism that would be most closely related among the given options would likely be:

**Yeast**

This makes yeast the best answer for sharing the most recent common ancestor with the unknown organism, assuming it is also a eukaryote.