Title: Animal Diversity
Course: Question Banks

Q: It is generally believed that the earliest animals evolved from ________.
- bacteria (Incorrect. Bacteria are not thought to be the direct ancestors of early animal life.)
- archaea (Incorrect. Archaea are not thought to be the direct ancestors of early animal life.)
- protists (Correct. Early animal life most likely evolved from protists resembling the modern day choanoflagellates.)
A: protists

Q: Most scientists generally hold that animal life appeared during the ________ period, though recent discoveries are challenging that understanding.
- Cryogenian (Incorrect. There is increasing evidence that early animal life may have evolved during the Cryogenian period but this is not the most widely accepted theory.)
- Cambrian (Incorrect. Animal life was well established by the Cambrian period of the Paleozoic Era.)
- Ediacaran (Correct. The most widely accepted theory has animal life evolving during the Ediacaran period at the end of the Proterozoic Era.)
A: Ediacaran

Q: The oldest animals with hard body parts were recently discovered in ________.
- South Africa (Incorrect. The oldest animals with hard body parts were not recently discovered in South Africa.)
- South America (Incorrect. The oldest animals with hard body parts were not recently discovered in South America.)
- South Australia (Correct. These sponge-like fossils date to approximately 560 million years ago.)
A: South Australia

Q: Most of the animal phyla in existence today appeared during the ________ explosion.
- Cryogenian (Incorrect. There is increasing evidence that early animal life may have evolved during the Cryogenian period but this period was not known for rapid evolution of animals.)
- Ediacaran (Incorrect. The most widely accepted theory has animal life evolving during the Ediacaran period at the end of the Proterozoic Era, but not rapidly evolving into diverse phyla.)
- Cambrian (Correct. Animal life and diversity rapidly evolved during the Cambrian period, giving rise to the term “Cambrian explosion.”)
A: Cambrian

Q: A dominant species during the Cambrian period was the ________.
- horseshoe crab (Incorrect. Horseshoe crabs are morphologically similar to this dominant species.)
- troglodytes (Incorrect. Troglodyte means “cave dweller” and refers to either extinct humans or solitary human hermits.)
- trilobite (Correct. Trilobites are extinct arthropods that thrived during the Cambrian period.)
A: trilobite

Q: The change in atmospheric oxygen concentrations is one possible factor that contributed to the ________.
- end-Permian mass extinction that wiped out 95 percent of the extant species on Earth (Incorrect. Changes in atmospheric oxygen did not contribute to a mass extinction event during the Permian.)
- rise of the dinosaurs at the beginning of the Triassic period (Incorrect. Changes in atmospheric oxygen did not contribute to the rise of dinosaurs in the Triassic period.)
- sharp increase in animal diversity during the Cambrian period (Correct. Rising atmospheric oxygen, along with increases in oceanic calcium concentrations, may have preceded and facilitated the Cambrian explosion.)
A: sharp increase in animal diversity during the Cambrian period

Q: ________ first appeared on land shortly after the Cambrian period.
- Animals (Incorrect. Plant life had to colonize the land before animals could leave the water for terrestrial life.)
- Insects (Incorrect. Insects are simply a type of animal.)
- Plants (Correct. Plant life had to colonize the land before animals could leave the water for terrestrial life.)
A: Plants

Q: A ________ is the devastating and rapid loss of genetic diversity.
- bottleneck (Incorrect. A bottleneck is a localized reduction in genetic diversity (at the level of a population).)
- collapse (Incorrect. The term “collapse” is not used to refer to this phenomenon in evolutionary history.)
- mass extinction (Correct. The key with mass extinctions is they involve a number of different species, sometimes even entire phyla.)
A: mass extinction

Q: The largest mass extinction occurred at the end of the ________ period, and facilitated the rise of the dinosaurs.
- Triassic (Incorrect. A mass extinction did occur at the end of the Triassic period but this is not the largest in prehistory.)
- Cretaceous (Incorrect. The end-Cretaceous mass extinction wiped out the dinosaurs.)
- Permian (Correct. The end-Permian mass extinction wiped out 95 percent of the extant species on Earth. Dinosaurs rose to dominate the planet afterwards.)
A: Permian

Q: Animals are primarily classified based on ________.
- genetic and biochemical markers (Incorrect. While modern genetic and biochemical studies may modify classifications, the majority of animals are not classified using these features.)
- genetic and developmental features (Incorrect. Animal classifications are not based on these features overall.)
- morphological and developmental features (Correct. Animal classification is largely based on morphological and developmental features such as body plans.)
A: morphological and developmental features

Q: Animals with three germ layers are further characterized by the presence or absence of a ________.
- vertebral column (Incorrect. This is a more granular layer of characterization that occurs at a lower taxonomic layer.)
- mesoderm (Incorrect. This is the third germ layers, so is involved in classifying animals based on two versus three germ layers.)
- coelom (Correct. The presence or absence of a coelom is the next feature used to characterize animals after the number of germ tissue layers.)
A: coelom

Q: All animals are ________.
- eumetazoans (Incorrect. This term means “true animal”; there are actually animals that do not fall into this group.)
- macroscopic (Incorrect. There are a number of microscopic animals, including arthropods and crustaceans.)
- metazoans (Correct. Another term for animal is metazoa.)
A: metazoans

Q: The most basic division of animals is based on whether or not they have ________.
- body symmetry (Incorrect. Body symmetry is inherent in the feature that is used to divide animals into “true” versus “beside” animals. But the type of symmetry is used to divide animals after the most basic distinction.)
- two or three germ layers (Incorrect. This level of classification is not the most basic dividing line in the animal kingdom.)
- differentiated tissues (Correct. Eumetazoa, or “true animals,” all have differentiated tissues. Parazoa, or “beside the animals,” have no tissues. These are the sponges.)
A: differentiated tissues

Q: The ________ contain cells that strongly resemble the protist ancestor of animals.
- comb jellies (Incorrect. Comb jellies do not include choanoflagellate-like cells.)
- cnidarians (Incorrect. Cnidarians do not include choanoflagellate-like cells.)
- sponges (Correct. The choanocyte cells of sponges resemble the choanoflagellate protists thought to closely resemble the animal ancestor.)
A: sponges

Q: True animals are divided into clades based on ________.
- differentiated tissues (Incorrect. Eumetazoa, or “true animals,” all have differentiated tissues. Parazoa, or “beside the animals,” have no tissues. These are the sponges.)
- two or three germ layers (Incorrect. This level of classification is not the first used on the true animals.)
- body symmetry (Correct. Body symmetry is inherent in having tissues, but it may be radial symmetry or bilateral symmetry, the next characteristic used to group animals.)
A: body symmetry

Q: Modern phylogenetics is influenced by ________ analyses.
- morphological (Incorrect. Morphological data built previous phylogenetic trees that are being actively refined with modern tools.)
- more powerful microscopic (Incorrect. More powerful microscopes are available today but they are not used as a stand-alone tool in phylogenetics.)
- nucleic acid and protein (Correct. Modern phylogenetics is rewriting animal classification, using nucleic acid and protein based data.)
A: nucleic acid and protein

Q: rRNA data has reclassified the ________ as a type of protostome.
- annelids (Incorrect. Annelids were always considered protostomes.)
- ecdysozoans (Incorrect. This clade was always composed of animals considered protostomes.)
- lophophorates (Correct. Previously these animals were considered primitive deuterostomes but now are thought to be protostomes.)
A: lophophorates

Q: The ________ may be living species of some of the earliest bilaterians.
- nematodes (Incorrect. Nematodes are not considered to be representative of the earliest bilaterians.)
- bryozoans (Incorrect. The bryozoans are not considered to be representative of the earliest bilaterians.)
- acoelmorphs (Correct. Modern evidence indicates these acoel flatworms may not be flatworms but rather are living representatives of some of the earliest divergent bilaterians.)
A: acoelmorphs