The Following Question Refers to This Phylogenetic Tree, Depicting the Origins

question 5

Multiple Choice

The following question refers to this phylogenetic tree, depicting the origins of life and the three domains. Horizontal lines indicate instances of gene or genome transfer.

A possible phylogenetic tree for the three domains of life.
If the early history of life on Earth is accurately depicted by the figure, then which statement is most in agreement with the hypothesis proposed by this tree?

• A) The last universal common ancestor of all extant species is one individual species.
• B) The origin of the three domains appears as a polytomy.
• C) Archaean genomes should not contain genes that originated in bacteria, and vice versa.
• D) Eukaryotes are more closely related to archaeans than to bacteria.

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Definitions:

Vascular Cambium

A layer of plant tissue located between the xylem and the phloem that is responsible for the secondary growth of stems and roots, allowing them to increase in thickness.

Cork Cambium

A layer of tissue in plants that produces cork (phellem) cells for protection and waterproofing.

Lignin

A complex organic polymer found in the cell walls of many plants, making them rigid and woody and providing structural support.

Sclerenchyma

In plants, simple tissue composed of cells that die when mature; their tough walls structurally support plant parts. Includes fibers, sclereids.