An evolutionary model of animal development indicates that _____.
A) differentiation is positional within a zygote
B) homeotic genes are not universal among animals
C) homeotic genes are found only in fruit flies, where they are responsible for odd placement of appendages
D) new genetic lines are produced less by modification than by unique mutation
E) somitesform as blocks of genes in cells randomly distributed throughout the body

Question

An evolutionary model of animal development indicates that _____.
A) ​differentiation is positional within a zygote
B) ​homeotic genes are not universal among animals
C) ​homeotic genes are found only in fruit flies, where they are responsible for odd placement of appendages
D) ​new genetic lines are produced less by modification than by unique mutation
E) ​somitesform as blocks of genes in cells randomly distributed throughout the body

Quizplus · Accepted Answer

An evolutionary model of animal development known as positional differentiation suggests that the location of a cell within a developing zygote is crucial in determining the type of cell it will differentiate into.

Answer: B
 Homeotic genes, which play a role in controlling the placement of body parts during development, are thought to be universal among animals.

Answer: D
 The evolution of new genetic lines is more likely to result from unique mutations rather than modification of existing genes.

Answer: E
 Somites are formed by random distribution of genes within the body, rather than as distinct blocks.

An Evolutionary Model of Animal Development Indicates That _____