Table 32.1. Proposed Number of Hox Genes in Various Extant and Extinct Animals

-What conclusion is apparent 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) Acoel flatworms should be expected to contain seven Hox genes.
D) The expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster.
E) Extant insects all have seven Hox genes.

Question

Table 32.1. Proposed Number of Hox Genes in Various Extant and Extinct Animals
 
-What conclusion is apparent 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) Acoel flatworms should be expected to contain seven Hox genes. 
D) The expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster. 
E) Extant insects all have seven Hox genes.

Quizplus · Accepted Answer

The table shows that the number of Hox genes varies greatly among different animal groups, with some having only a few (such as cnidarians and placozoans) and others having many (such as jawed vertebrates). The fact that such a wide range of numbers exist suggests that the expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster, as stated in option D. Therefore, this is the best choice.

Table 321 Proposed Number of Hox Genes in Various Extant and and Extinct