A Phylogenetic Tree Is Shown for the Three Domains of Life

question 47

Multiple Choice

A phylogenetic tree is shown for the three domains of life (Eukarya, Archaea, and Bacteria) . The tree branches in two directions from the first point, labeled Common ancestor of all life. One branch leads in the direction of Eukarya and Archaea, and the other branch leads to Bacteria. The branch leading to Eukarya and Archaea divide, one branch leading to each domain. The branch leading to Eukarya divides into four branches. One leads to Euglenozoans, and the other three lead to branching points. The first leads to Forams in one direction, and another branching point in the other that leads to Diatoms and Ciliates. The second branching point leads to Red algae in one direction, and a branching point that leads to green algae and land plants in the other direction. The third branching point leads to amoebas in one direction, and a branching point that leads to fungi and animals in the other direction. Land plants, Fungi and Animals are all highlighted.
Cyanobacteria were once called blue-green algae because they are photosynthetic. According to the phylogeny shown, the cyanobacteria are more closely related to gram-positive bacteria than to ________.

• A) proteobacteria
• B) green algae
• C) euglenozoans
• D) crenarcheotes

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Definitions:

Fischer Projection

A method to represent the three-dimensional structure of molecules on a two-dimensional plane, emphasizing the configuration of chiral centers.

Fischer Projection

A two-dimensional representation of a three-dimensional organic molecule by projecting bonds from a chiral center, used to depict stereochemistry.

Chiral

Describes a molecule that cannot be superimposed on its mirror image, often resulting in molecules that have different biological activities.

Asymmetric Carbons

Carbon atoms bonded to four different groups, creating a chiral center and leading to possible optical isomerism.