USC BISC 120 Final Exam Trond Sigurdsen Questions and Answers
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USC BISC 120 Trond Sigurdsen
USC BISC 120 Final Exam Trond Sigurdsen
What is the largest group of deuterostomes? - Answer- chordates
Chordates are mostly vertebraes or invertebrates? Primitive chordates have this structure - Answer- They are mostly vertebrates but there are some primitive forms with a notochord
What a...
USC BISC 120 Final Exam Trond
Sigurdsen
What is the largest group of deuterostomes? - Answer- chordates
Chordates are mostly vertebraes or invertebrates? Primitive chordates have this
structure - Answer- They are mostly vertebrates but there are some primitive forms
with a notochord
What are the three types of chordates? - Answer- vertebrates, lancelets, tunicates
What is the amphioxus? - Answer- a lancelet
These two are the simplest chordates - Answer- lancelets and tunicates
What do lancelets and tunicates lack? What do they have instead? - Answer- They
lack a vertebral column but have a notochord as juveniles. Adult lancelets also have
a notochord
What are the five notable features of chordates? - Answer- dorsal hollow nerve cord,
dorsal supportive notochord, pharyangeal slits/pouches, post-anal tail, myotomes
Where is the nerve cord located in comparison to the notochord? - Answer- The
nerve cord is dorsal to the notochord
What are the pharyngeal slits in lancelets and fish? - Answer- Gill slits
Are adult tunicates motile or sessile? - Answer- sessile
What two openings do tunicates have? - Answer- incurrent and excurrent siphone
What do large apparatus do tunicates use to filter water? - Answer- the pharynx
Describe the larva of tunicates - Answer- free-swimming with typical chordate
characteristics
What does the dorsal hollow nerve cord develop into? - Answer- It develops into the
central nervous system,: spinal cord and brain
How does the dorsal hollow nerve cord originate? What is a byproduct of this
process? - Answer- Originates embryonically as a folding of ectoderm dorsal to the
notochord. Also, neural crest cells are "pinched off" in this process.
What three tissues do neural crest cells give rise to? - Answer- Many bones in the
skull, sensory neurons, and pigment cells in skin (melanocytes)
,In vertebrates, the vertebrae form around these two structures - Answer- the
notochord and spinal cord
Vertebrae start as this material and then form this material - Answer- cartilage turns
to bone
In many species of vertebrates, the notochord persists through this structure -
Answer- the vertebral column
In humans, a small piece of notochord called the nucleus pulposus is found in this
structure? - Answer- intervertebral disk
This bone protects the brain and sensory system in the head - Answer- the cranium
What are the most primitive/basal vertebrates? What are they considered to be?
Why? - Answer- the hagfish and lamprey. they are cyclostomes because they have
no jaw
This is another term for fish - Answer- pisces
What is the term "fish" traditionally defined as? - Answer- Traditionally very vague;
meaning almost any animal in the seas/fresh water
The term "fish" is now thought of as - Answer- Vertebrata minus Tetrapoda
In cyclostomes, what supports the mouth? What are the teeth made of? - Answer-
Mouth supported by musculature (not skeleton) and teeth made of horny material
Describe the location of fins on cyclostomes - Answer- Fins along the body, but not
paired
Describe the skeleton of cyclostomes? What is the important part? What is the rest
made of? - Answer- Skeleton: notochord is an important part, rest is made from
cartilage (and relatively simple),
This group of cyclostomes are considered to be the most primitive surviving
vertebrates - Answer- hagfish (rudimentary vertebrate)
The term for a jawless fish that also includes extinct species like connodonts is -
Answer- agnathan
What do hagfish eat? - Answer- They are scavengers who eat rotting fish, dead
whales etc., sometimes carnivorous
What is a defense mechanism of hagfish? - Answer- Glands along body produce
copious amounts of slime to deter potential predators
Unlike hagfish, lampreys have this structure - Answer- a true vertebral column
composed of cartilaginous vertebrae
, Despite having a true vertebral column made of cartilage, the main skeletal support
structure of lampreys is still this - Answer- notochord
Lampreys are this type of parasite, what do they eat? - Answer- ectoparasites who
eat tissue and drink blood
What are jawed vertebrates called - Answer- gnathostomes
What are the three common components of a gnathostome? - Answer- jaws (skeletal
support of mouth), paired fins (pectoral and pelvic fins), lateral line system (sensory
system along the body)
How are jaws believed to have evolved? - Answer- Jaws may have evolved by
modifications of skeletal support (gill arches) of the anterior pharyngeal slits (gill
slits). They might have originally been part of a system for filter feeding and
respiration
The development of these two structures allowed for fish to become more active and
to bite off chunks of food. - Answer- jaw and paired fins
What structures compose the lateral line system? What does this system do? -
Answer- Fish have canals in the skin with pores. They also have cupula with sensory
hairs (neuromast sensory organs) that can sense water displacement
What are the four lineages of gnathostomes? - Answer- chondrichthyans, ray-finned
fish, lobe-finned fish, tetrapods
These two gnathostome lineages are considered to be "bony fish" (osteichthyans) -
Answer- ray-finned and lobe-finned fish
Chondrichthyans include - Answer- Sharks, rays, ratfish (chimaera)
What are chondrichthyan skeletons made of? - Answer- cartilage
Describe the gill slits of chondrichthyans - Answer- Most have separate gill slits
(except chimaera, with operculum)
Are sharks predators? - Answer- yes
Which species of shark has the best electroreceptors? - Answer- hammerhead shark
Why do sharks not sink? - Answer- They are heavier than water but their oily liver
keeps them buoyant
In addition to sight, hearing, smell, and sensitive lateral lines, sharks also have this
sensing structure - Answer- electroreceptors on the head
What is another name for bony fish (ray/lobe fins) - Answer- osteichthyans
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