BIOL 112 Final Exam Review

What are the 4 characteristics that all chordates have at some point during their development?

1. Notochord

2. Dorsal hollow nerve cord

3. Pharyngeal gill slits

4. Post-anal tail

What does the notochord become in vertebrates?

The vertebrae.

What does the dorsal hollow nerve cord become in vertebrates?

The spinal cord.

Pharyngeal gill slits become what in vertebrate fish and tetrapods?

In vertebrate fish it becomes the gill supports. In tetrapods it becomes parts of the jaws, ears, and tonsils.

What are the unique features of lancelets (Cephalochordata)?

All of the key chordate features present in the adult. Cilia draw seawater into its mouth, as they are filter-feeders.

What is unique about tunicates, or sea squirts (Urochordata)?

Their larva has all key chordate features, but in adulthood they become sessile so they lose everything except their pharyngeal slits.

What are the two pieces that make up vertebrate endoskeletons? And what bones make up those two pieces?

The axial skeleton and the appendicular skeleton.
Axial Skeleton: Skull, vertebrae, ribs.

Appendicular Skeleton: Pectoral and pelvic area.

What does the presence of a skeletal and complex nervous system grant vertebrates more efficiency in?

Capturing food and evading predators.

What is the main difference between Cyclosomes and Gnathostomes?

Cyclosomes lack jaws and have eel-like bodies with reduced vertebrae. Gnathostomes have hinged jaws with mineralized skeleton and usually also have bony teeth.

Define osmoregulation.

The process of maintaining internal osmotic pressure at homeostasis when external environment changes.

What is the difference between being an osmocomformer and an osmoregulator? Of the two, gnathostomes are notably which kind?

Osmocomforing is that the solutes in their tissues in their bodies will attempt to conform to the solutes present in the water/environment. Most aquatic vertebrates are osmocomforing. Osmoregulating means that the solutes in their tissues remain constant even as the environment changes. Gnathostomes are notably all osmoregulators.

What are the most diverse group of Gnathostomes?

Chondrichthyes. They consist of shark, rays, and skates.

What is the central important feature to Chondrichthyes?

Their skeletons are made of cartilage to help reduce density.

Chondrichthyes are known for which kind of fertilization?

Interal fertilization.

Explain the difference between oviparous, viviparous, and ovoviviparous present in Chondrichthyes.

Oviparous - Eggs are laid and hatched outside of the mother’s body. The embryo develops in a protective egg-case.

Viviparous - Young develop inside uterus. Obtain nutrients transferred via mother’s blood. Ends in a live birth.
Ovoviviparous - Fertilized egg retained within mother. Embryo fed via yolk sac. Ends in a live birth.

What is the name of the group that most fish people think of would be categorized under?

Osteichthyes. Ray-finned and lobe-finned fish are here.

What is the difference between a ray-finned fish and a lobe-finned fish?

Ray-finned fish have thin fins supported by long flexible rays that are modified for maneuvering, defense, etc. Lobe-finned fish are fish with pelvic and pectoral fins supported by bones and muscles.