Use the Table to Answer the Question What Conclusion Can Best Be Drawn from the Data in Hox

question 18

Multiple Choice

Use the table to answer the question.
Proposed Number of Hox Genes in Various Extant and Extinct Animals
$$\begin{array} { | c | c | c | c | } \begin{array} { c } \hline \text { Last } \\\text { Common } \\\text { Ancestor } \\ { of Bilateria }\end{array} & \begin{array} { c } \hline \\\text { Last Common } \\\text { Ancestor of Insects } \\\text { and Vertebrates }\end{array} & \begin{array} { c } \hline\\\\\text { Ancestral } \\\text { Vertebrates }\end{array} & \text { Mammals } \\\hline 4 & 7 & 14 & 38-40 \\\hline\end{array}$$
What conclusion can best be drawn from the data in the table?

• A) Land animals have more Hox genes than do those that live in water.
• B) All bilaterian phyla have had the same degree of expansion in their numbers of Hox genes.
• C) The expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster.
• D) Extant insects all have seven Hox genes.

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Definitions:

ATP

Involved in metabolic processes, ATP (adenosine triphosphate) is the key energy transporter in cells.

Ingestion

The method by which food, liquids, or other substances are introduced into the body through swallowing or absorption.

Active Transport

A cellular process that requires energy to move substances across cell membranes against a concentration gradient.

Concentration Gradient

The gradual difference in the concentration of solutes in a solution between two regions. In biology, it often refers to differences across a membrane.