BIOL 1108 Exam 1 Guide 2026 [Latest
Update] | Principles of Biology II | 100%
Verified Q&A | Grade A
Question 1: Which of the following is the defining characteristic of all chordates at some stage of
development?
A) Dorsal hollow nerve cord
B) Ventral solid nerve cord
C) Exoskeleton
D) Book lungs
Correct Answer: A) Dorsal hollow nerve cord
Explanation: All chordates possess a dorsal hollow nerve cord that develops into the spinal cord
and brain, distinguishing them from other animal phyla.
Question 2: The notochord in adult lancelets (Cephalochordata) functions primarily as
A) a site of blood cell production
B) a rigid axial support for locomotion
,C) a respiratory organ
D) an excretory organ
Correct Answer: B) a rigid axial support for locomotion
Explanation: Lancelets retain the notochord throughout life, using its turgid, flexible structure for
burrowing and swimming.
Question 3: Which extra-embryonic membrane encloses the embryo in a fluid-filled sac in amniotic
eggs?
A) Chorion
B) Allantois
C) Amnion
D) Yolk sac
Correct Answer: C) Amnion
Explanation: The amnion forms a protective, water-filled cavity that prevents desiccation and
mechanical shock during terrestrial development.
Question 4: The evolution of the amniotic egg allowed vertebrates to
A) reproduce in marine environments without salt glands
B) complete embryonic development on land without risk of desiccation
, C) increase the number of eggs produced
D) eliminate the need for internal fertilization
Correct Answer: B) complete embryonic development on land without risk of desiccation
Explanation: Extra-embryonic membranes created a private aquatic environment, freeing amniotes
from dependence on external water for reproduction.
Question 5: Which of the following is a synapomorphy of all gnathostomes?
A) Single semicircular canal
B) Jaws and paired appendages
C) Bony endoskeleton
D) Lungs
Correct Answer: B) Jaws and paired appendages
Explanation: Jaws and paired fins/flippers are derived traits that improved feeding efficiency and
locomotion in vertebrates.
Question 6: Monotremes differ from other extant mammals by
A) possessing a placenta
B) laying shelled eggs
C) having nipples
Update] | Principles of Biology II | 100%
Verified Q&A | Grade A
Question 1: Which of the following is the defining characteristic of all chordates at some stage of
development?
A) Dorsal hollow nerve cord
B) Ventral solid nerve cord
C) Exoskeleton
D) Book lungs
Correct Answer: A) Dorsal hollow nerve cord
Explanation: All chordates possess a dorsal hollow nerve cord that develops into the spinal cord
and brain, distinguishing them from other animal phyla.
Question 2: The notochord in adult lancelets (Cephalochordata) functions primarily as
A) a site of blood cell production
B) a rigid axial support for locomotion
,C) a respiratory organ
D) an excretory organ
Correct Answer: B) a rigid axial support for locomotion
Explanation: Lancelets retain the notochord throughout life, using its turgid, flexible structure for
burrowing and swimming.
Question 3: Which extra-embryonic membrane encloses the embryo in a fluid-filled sac in amniotic
eggs?
A) Chorion
B) Allantois
C) Amnion
D) Yolk sac
Correct Answer: C) Amnion
Explanation: The amnion forms a protective, water-filled cavity that prevents desiccation and
mechanical shock during terrestrial development.
Question 4: The evolution of the amniotic egg allowed vertebrates to
A) reproduce in marine environments without salt glands
B) complete embryonic development on land without risk of desiccation
, C) increase the number of eggs produced
D) eliminate the need for internal fertilization
Correct Answer: B) complete embryonic development on land without risk of desiccation
Explanation: Extra-embryonic membranes created a private aquatic environment, freeing amniotes
from dependence on external water for reproduction.
Question 5: Which of the following is a synapomorphy of all gnathostomes?
A) Single semicircular canal
B) Jaws and paired appendages
C) Bony endoskeleton
D) Lungs
Correct Answer: B) Jaws and paired appendages
Explanation: Jaws and paired fins/flippers are derived traits that improved feeding efficiency and
locomotion in vertebrates.
Question 6: Monotremes differ from other extant mammals by
A) possessing a placenta
B) laying shelled eggs
C) having nipples
