Chordates are characterized by organisms that have at least a dorsal nerve cord, a notochord, pharyngeal pouches, and a tail.

D. II and III

Vertebrates are capable of controlling their body temperature internally (endotherms) and externally (ectotherms). Endotherms have high metabolic rate which produces body heat. To insulate their bodies, they have adaptations like feathers, furs, or hairs. To release heat, they pant or sweat. Ectotherms rely on the environment for body heat. They either receive or release heat by interacting with environment.

E. I, II, and III

Breathing occurs when oxygen is inhaled into the lungs. Oxygen goes into the trachea then lung capillaries. Once oxygen is absorbed by the cells, carbon dioxide is released. In turn, the carbon dioxide is diffused into the lung capillaries and exhaled out of the body.

D. exhalation of oxygen-rich air

A four-chambered heart has two atria (left and right) and two ventricles that are completely divided. Since the ventricles have a partition, there is no mixing of oxygenated and deoxygenated blood.

E. no mixing of oxygen-rich and oxygen-poor blood

If an animal is oviparous, it lays eggs that are fertilized inside the female’s body. The egg contains an embryo that is enclosed in a hard outer shell and membranes. The embryo continues to develop outside the mother’s body.

D. develop outside the body

The cerebrum is responsible for the thoughts, actions and higher thinking functions of the brain.

B. cerebrum

Reptiles are unable to excrete ammonia directly. Instead, they convert ammonia into uric acid.

C. uric acid

According to the cladogram, the notochord appeared in trout, wallabies, and humans.

B. notochord

According to the cladogram, the closest evolutionary relationship is found between wallabies and humans. They both have a backbone, four limbs, and mammary glands.

A. humans and wallabies

All nonvertebrate and verbrate chordates share a common ancestor that contains a notochord. Therefore, humans and lampreys share a common ancestor.

C. humans and lampreys share a common ancestor