Question

As a final exam question in your biology course, you are asked to identify an animal that you immediately recognize as a chordate. Your instructor applauds you for your quick recognition of the phylum, but then he asks you to be more specific. You reply that the animal that you are observing is a craniate. To get an A, you must also tell your instructor how you came up with your answer. What features would you use to formulate your answer?

A) Most craniates lack a functional jaw.
B) The anterior end of the nerve cord is elaborated to form a brain in craniates.
C) The brain is encased in a protective bony or cartilaginous housing in craniates.
D) Adult craniates lose most of their chordate characteristics.
E) A group of embryonic cells called the neural crest form on either side of the neural tube in craniates.

Answer 1

BCE

The anterior end of the nerve cord is elaborated to form a brain in craniates.

The brain is encased in a protective bony or cartilaginous housing in craniates.

A group of embryonic cells called the neural crest form on either side of the neural tube in craniates

Craniates are members of the craniate monophyletic group of chordinates. They have a distinct head , protected by the skull made of hard bone. Some are with cartilages. The skull protects the brain, paired eyes, ears and other the sensory organs.

They have high metabolic demands, their cardiovascular systems is made up of heart with one to two chambers. Its pumps blood saturated with oxygen, carried by hemoglobin. They have kidney which maintain homeostasis

Step-by-step explanation:

Answer 2

Answer: c) and b) are correct.

The brain is encased in a protective bony or cartilaginous housing in craniates.

The anterior end of the nerve cord is elaborated to form a brain in craniates.

Explanation: The craniates include the chordata with well-defined heads. This includes mammals, reptiles and fishes. So we can discard the other answers. Because most craniates have functional jaws, and the adults do not lose their chordate characteristics. The last one does not apply as a specific feature because the tunicate have neural crest but are not recognized as craniata.