Theme 4

Question 1

Define an animal.

Answer 1

Animals are multicellular heterotrophs that ingest their food

Question 2

True or false: All animals exhibit bilateral symmetry during development

Answer 2

False

Question 3

Compared to the Cambrian explosion, the Ediacaran biota:

Answer 3

Lacks definitive examples of bilateral symmetry, limiting movement

Question 4

A metazoan embryo that forms a blastula but does not develop true tissues is most likely:

Answer 4

A member of the Porifera, such as a sponge

Question 5

Why can coral polyps capture plankton using their tentacles?

Answer 5

Cnidarians’ tentacles contain cnidocytes that can immobilize prey

Question 6

True or false: Nematoda are members of clade Lophotrochozoa

Answer 6

False

Question 7

True or false: Rotifera are members of clade Lophotrochozoa

Answer 7

True

Question 8

What evolutionary trade-offs are associated with the flat shape of Platyhelminthes?

Answer 8

Increased surface area for gas exchange but reduced structural support

Question 9

Scientists studying marine biodiversity discover a new species with a ciliated structure resembling a lophophore and trochophore-like larva during development. Which additional feature would support the classification of this species within Lophotrochozoa?

Answer 9

Spiral and determinate cleavage during embryonic development

Question 10

What is the ecological importance of free-living nematodes in nutrient cycling?

Answer 10

Nematode species decompose organic matter in agricultural soil, enhancing soil fertility

Question 11

What is a distinguishing feature of hexapod appendages compared to crustaceans?

Answer 11

Hexapods have uniramous legs, while crustaceans typically have biramous appendages

Question 12

How can chelicerates be distinguished from myriapods based on body plan?

Answer 12

Chelicerates have a cephalothorax and abdomen, while myriapods have a head and segmented trunk

Question 13

Crustaceans often exhibit biramous appendages. What does the presence of biramous appendages indicate about their evolutionary history?

Answer 13

An aquatic origin where one branch is specialized for locomotion and the other for gas exchange

Question 14

Insects, a subgroup of hexapods, are distinct from other arthropods in their ability to fly. What other morphological adaptation supports their terrestrial success?

Answer 14

A tracheal system for direct oxygen delivery to tissues

Question 15

Which differences can be used to distinguish millipedes from centipedes?

Answer 15

Millipedes are herbivorous and have two pairs of legs per segment, while centipedes are carnivorous with one pair per segment

Question 16

In vertebrates, the notochord is replaced by a vertebral column during development. Why is this evolutionary transition significant?

Answer 16

It supports the attachment of complex muscle systems for locomotion

Question 17

What distinguishes tunicates (urochordates) from lancelets (cephalochordates)?

Answer 17

Tunicates are sessile as adults, while lancelets retain mobility

Question 18

A fossil of a primitive chordate is discovered with an unusually short notochord but highly developed pharyngeal slits. What does this combination suggest about its ecological role and evolutionary development?

Answer 18

It relied heavily on filter feeding in aquatic ecosystems

Question 19

Basal vertebrates such as hagfishes and lampreys are collectively referred to as:

Answer 19

Cyclostomes

Question 20

What is a shared derived trait of gnathostomes?

Answer 20

Mineralized skeletal elements

Question 21

Lampreys use their oral sucker to attach to rocks or prey. What key morphological feature supports this behaviour?

Answer 21

A cartilaginous skeleton with a reinforced oral disc

Question 22

A student claims that endoskeletal bones and dermal bones serve identical roles in all vertebrates. Which observation disproves this claim?

Answer 22

Endoskeletal bones provide internal support, while dermal bones form protective external structures

Question 23

A unique feature of Chondrichthyans compared to bony fish is:

Answer 23

The presence of a cartilaginous skeleton without ossification

Question 24

Why are lungfish considered an important evolutionary bridge in the clade lobe-fins?

Answer 24

They demonstrate the dual use of lungs and gills in respiration

Question 25

Researchers discovered a fossilized vertebrate with a bony endoskeleton and maneuverable paired fins supported by flexible rays. The specimen lacks any evidence of lobed fins or terrestrial adaptations. To which group of Osteichthyans is this fossil most likely related?

Answer 25

Actinopterygii

Question 26

A researcher examines a fossilized Osteichthyan and finds evidence of both gills and a simple dorsal lung. The environment suggests the species lived in oxygen-poor, brackish water. What does this discovery indicate about the evolutionary pressures faced by early Osteichthyans?

Answer 26

They evolved lungs to supplement gill-based respiration

Question 27

Which feature made external fertilization less viable for early tetrapods on land?

Answer 27

Drying of gametes outside water

Question 28

What role did internal nostrils play in the transition to land?

Answer 28

Enabled lung ventilation at the water surface without opening the mouth

Question 29

Tiktaalik's pectoral fins contain skeletal elements homologous to tetrapod limbs. Scientists discovered jointed structures similar to a shoulder, elbow, and proto-wrist but no digits. How does Tiktaalik's limb structure reflect its transitional nature?

Answer 29

It could support itself partially in shallow waters

Question 30

Amphibians exhibit "naked skin" that lacks scales and has minimal keratin. How does this adaptation influence their ecological roles and vulnerabilities?

Answer 30

It facilitates efficient gas exchange but increases susceptibility to pollutants and desiccation

Question 31

Reptiles first evolved during the Carboniferous period. What major environmental shift during this time likely contributed to their rise?

Answer 31

Development of arid climates and decreasing water availability

Question 32

Lepidosaurs include snakes and lizards, which are highly diverse. What evolutionary advantage likely explains their success?

Answer 32

The development of loosely articulated, hinged jaws for greater feeding efficiency

Question 33

Which feature most strongly supports the hypothesis that birds evolved from theropod dinosaurs?

Answer 33

Hollow bones and feather-like structures in fossils

Question 34

What feature is birds ensures continuous oxygen delivery to meet the high metabolic demands of flight?

Answer 34

Unidirectional airflow through the lungs, facilitated by internal air sacs, ensures that air flows in a single direction during both inhalation and exhalation

Question 35

What traits made vertebrate evolution possible?

Answer 35

Ancestral chordate body plan, conserved Hox genes, and early whole genome duplications increasing developmental complexity

Question 36

Monotremes have a unique evolutionary history, being the most basal clade of mammals. Which of trait illustrates this basal position?

Answer 36

Laying leathery-shelled eggs similar to reptiles

Question 37

Which of adaptive trend evolved first in hominins?

Answer 37

Bipedal locomotion

Question 38

Australopith fossils reveal a narrower, more aligned foot compared to earlier hominins. How does this adaptation contribute to bipedal efficiency?

Answer 38

It reduces energy expenditure during locomotion

Question 39

What distinguishes Homo species from australopiths?

Answer 39

Increased brain size and tool use

Question 40

Arrange the following events in hominin evolution in the correct sequence: 1. Expansion of cranial capacity beyond 1,200 cc; 2. Migration out of Africa; 3. Development of bipedalism; 4. Appearance of Homo sapiens

Answer 40

3, 2, 1, 4