Given the Similar Genetic Network of Developmental Genes Among Bilaterians

question 3

Multiple Choice

Given the similar genetic network of developmental genes among bilaterians, what can we say about their common ancestor?

• A) It may have grown some kind of outgrowth from its body wall.
• B) It most likely had limbs used in movement.
• C) It most likely had three pairs of legs, similar to insects.
• D) none of the above

---

Definitions:

Flexion

A movement that decreases the angle between two body parts, such as bending an elbow or knee.

Extension

The movement by which the angle between two bones is increased, typically referring to limbs or joints.

Circumduction

A circular movement of a limb or eye that combines flexion, extension, abduction, and adduction.

Protraction

The act of moving a body part forward, as in pushing the shoulders or jaw forward.