Refer to the Figure

question 239

Multiple Choice

Refer to the figure. What modification in jaw structure occurred in early jawed fishes that was not found in jawless fishes at that time?

• A) A set of gill arches was modified into supports for the jaws.
• B) Gill arches were modified to form jaws.
• C) Teeth developed on the jaws.
• D) The anterior part of the skull was modified to form jaws.
• E) Teeth formed from posterior gill arches.

---

Definitions:

Optically Inactive

Describes compounds that do not rotate the plane of polarized light, usually because they are achiral or have a symmetrical arrangement of atoms.

Base-promoted Hydrolysis

A chemical reaction where a base speeds up the hydrolysis process, commonly involving cleavage of bonds by the addition of water.

Fats

Molecules composed of triglycerides that are solid at room temperature, commonly found in animals and some plants, and serve as a major energy source.

Oils

Organic substances that are liquid at room temperature and are insoluble in water but soluble in organic solvents.