Question

For chordates, all are true except

• A. Notochord
• B. Dorsal nerve cord
• C. Amnion
• D. Pharyngeal gill slits

Answer 1

The correct option is C

Amnion

The correct option is C.

Explanation for the correct option:

1. Amnion isn't found in every chordate.
2. Birds, reptiles, and mammals all have it.
3. The amnion is the membrane that surrounds the embryo and creates the fluid-filled amniotic sac.

Explanation for the incorrect options:

Option A:

1. Chordates get their name from the flexible skeletal rod comprised of cartilage.
2. The notochord is a support structure that runs between an animal's digestive tube and its nerve cord.

Option B:

1. A dorsal nerve cord is a section of the spinal cord that goes down an animal's back.
2. It is a hollow cord that develops from the dorsal section of the notochord into the brain and spinal cord.

Option D:

1. Chordates have pharyngeal gill slits, which are apertures between the pharynx and the outside world.
2. They've been altered during the course of evolution.

Final Answer: In chordates notochord, dorsal nerve cord, and pharyngeal gill slits are found except amnion.