Question 1

Whatever its ultimate cause(s), the Cambrian explosion is a prime example of

Accepted Answer

A) mass extinction. 
B) evolutionary stasis. 
C) adaptive radiation. 
D) All three of the responses are correct. 
E) Only two of the responses are correct. 
A) mass extinction. 
B) evolutionary stasis. 
C) adaptive radiation. 
D) All three of the responses are correct. 
E) Only two of the responses are correct.

Question 2

The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, except Nematostella (of β-catenin fame), which has three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that

Accepted Answer

A) Radiata should be a true clade. 
B) the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait. 
C) Hox genes play little actual role in coding for an animal's "body plan." 
D) Cnidaria may someday replace Acoela as the basal bilaterians. 
E) Two of the responses above are correct. 
A) Radiata should be a true clade. 
B) the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait. 
C) Hox genes play little actual role in coding for an animal's "body plan." 
D) Cnidaria may someday replace Acoela as the basal bilaterians. 
E) Two of the responses above are correct.

Question 3

Use the following information to answer the questions below.
The most recently discovered phylum in the animal kingdom (1995) is the phylum Cycliophora. It includes three species of tiny organisms that live in large numbers on the outsides of the mouthparts and appendages of lobsters. The feeding stage permanently attaches to the lobster via an adhesive disk, and collects scraps of food from its host's feeding by capturing the scraps in a current created by a ring of cilia. The body is sac-like and has a U-shaped intestine that brings the anus close to the mouth. Cycliophorans are eucoelomate, do not moult (though their host does), and their embryos undergo spiral cleavage.
-Cycliophorans have two types of larvae. One type of larva is produced when the digestive system of a female is impregnated by a male. The digestive system then collapses and develops into a larva, which swims away in search of a new host after the surrounding female dies. Which is the embryonic tissue that is apparently most important in forming this type of larva?

Accepted Answer

A) mesohyl 
B) mesoderm 
C) ectoderm 
D) endoderm 
E) mesoglea 
A) mesohyl 
B) mesoderm 
C) ectoderm 
D) endoderm 
E) mesoglea

Question 4

Use the following information to answer the questions below.
Trichoplax adhaerens (Tp) is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. They move using cilia, and any "edge" can lead. Tp feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. Tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.
-On the basis of information in the previous paragraph, which of these should be able to be observed in Tp?

Accepted Answer

A) the act of fertilization 
B) the process of gastrulation 
C) eggs 
D) All three of the responses above are correct. 
E) Two of the responses above are correct. 
A) the act of fertilization 
B) the process of gastrulation 
C) eggs 
D) All three of the responses above are correct. 
E) Two of the responses above are correct.

Question 5

Use the following information to answer the questions below.
Trichoplax adhaerens (Tp) is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. They move using cilia, and any "edge" can lead. Tp feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. Tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.
-In an experiment, several Tp individuals were stained different colours. The stained individuals were then passed through a strainer, disaggregated to the level of single cells, and collected into a common container of sea water. Which subsequent finding would be most surprising if the Tp individuals used in this experiment had been produced by sexual, rather than asexual, means?

Accepted Answer

A) If all of the cells from a given individual reaggregated to form the same individual, and if each cell had retained its original identity, as far as cell type goes. 
B) If all of the cells from a given individual reaggregated to form the same individual, but if each cell had a different identity than it had before disaggregation. 
C) If cells from different original individuals reaggregated together to form new individual organisms. 
D) If cells from different original individuals reaggregated together to form new species. 
A) If all of the cells from a given individual reaggregated to form the same individual, and if each cell had retained its original identity, as far as cell type goes. 
B) If all of the cells from a given individual reaggregated to form the same individual, but if each cell had a different identity than it had before disaggregation. 
C) If cells from different original individuals reaggregated together to form new individual organisms. 
D) If cells from different original individuals reaggregated together to form new species.

Question 6

Evidence of which structure or characteristic would be most surprising to find among fossils of the Ediacaran fauna?

Accepted Answer

A) true tissues 
B) hard parts 
C) bilateral symmetry 
D) cephalization 
E) embryos 
A) true tissues 
B) hard parts 
C) bilateral symmetry 
D) cephalization 
E) embryos

Question 7

Which statement is most consistent with the hypothesis that the Cambrian explosion was caused by the rise of predator-prey relationships?

Accepted Answer

A) increased incidence of worm burrows in the fossil record 
B) increased incidence of larger animals in the fossil record 
C) increased incidence of organic material in the fossil record 
D) increased incidence of fern galls in the fossil record 
E) increased incidence of hard parts in the fossil record 
A) increased incidence of worm burrows in the fossil record 
B) increased incidence of larger animals in the fossil record 
C) increased incidence of organic material in the fossil record 
D) increased incidence of fern galls in the fossil record 
E) increased incidence of hard parts in the fossil record

Question 8

Which of the following traits differentiates animals from plants and fungi?

Accepted Answer

A) are eukaryotes 
B) contain collagen 
C) are multicellular 
D) have a cell wall 
E) A and D 
A) are eukaryotes 
B) contain collagen 
C) are multicellular 
D) have a cell wall 
E) A and D

Question 9

Protostome characteristics generally include which of the following?

Accepted Answer

A) a mouth that develops secondarily, and far away from the blastopore 
B) radial body symmetry 
C) radial cleavage 
D) determinate cleavage 
E) absence of a body cavity 
A) a mouth that develops secondarily, and far away from the blastopore 
B) radial body symmetry 
C) radial cleavage 
D) determinate cleavage 
E) absence of a body cavity

Question 10

The following questions refer to the description below.
You have taken an introductory course in animal biology and know that animals have evolved with different types of symmetry. Animals that show radial symmetry have a top and bottom, but do not have a left or right side, nor a front or back end. Animals that show bilateral symmetry have a top and bottom, left and right sides, and distinct anterior and posterior ends.
-You and a friend have flown to the coast of British Columbia to do some hiking and whale watching. As you are walking along the beach collecting shells, you notice a strange animal washed up on the beach and it is not a species that you recognize. Just by looking at the animal, what is a quick way that you can surmise the animal's mode of locomotion and method of food acquisition?

Accepted Answer

A) You need to put it back into the water and observe it. 
B) Bilaterally symmetrical animals will show directed movement while radially symmetrical animals tend to be sedentary. 
C) Bilaterally symmetrical animals will likely capture prey, while radially symmetrical animals will likely be filter feeders. 
D) Bilaterally symmetrical animals will likely feed as they move fast, while radially symmetrical animals will likely move slower and feed on injured or dead prey. 
E) B and C 
A) You need to put it back into the water and observe it. 
B) Bilaterally symmetrical animals will show directed movement while radially symmetrical animals tend to be sedentary. 
C) Bilaterally symmetrical animals will likely capture prey, while radially symmetrical animals will likely be filter feeders. 
D) Bilaterally symmetrical animals will likely feed as they move fast, while radially symmetrical animals will likely move slower and feed on injured or dead prey. 
E) B and C

Question 11

Which of the following is descriptive of protostomes?

Accepted Answer

A) spiral and indeterminate cleavage, blastopore becomes mouth 
B) spiral and determinate cleavage, blastopore becomes mouth 
C) spiral and determinate cleavage, blastopore becomes anus 
D) radial and determinate cleavage, blastopore becomes anus 
E) radial and determinate cleavage, blastopore becomes mouth 
A) spiral and indeterminate cleavage, blastopore becomes mouth 
B) spiral and determinate cleavage, blastopore becomes mouth 
C) spiral and determinate cleavage, blastopore becomes anus 
D) radial and determinate cleavage, blastopore becomes anus 
E) radial and determinate cleavage, blastopore becomes mouth

Question 12

With the current molecular-based phylogeny in mind, rank the following from most inclusive to least inclusive. 1. ecdysozoan
2. protostome
3. eumetazoan
4. triploblastic

Accepted Answer

A) 4, 2, 3, 1 
B) 4, 3, 1, 2 
C) 3, 4, 1, 2 
D) 3, 4, 2, 1 
E) 4, 3, 2, 1 
A) 4, 2, 3, 1 
B) 4, 3, 1, 2 
C) 3, 4, 1, 2 
D) 3, 4, 2, 1 
E) 4, 3, 2, 1

Question 13

The figure above shows a chart of the animal kingdom set up as a modified phylogenetic tree. Use the diagram to answer the following questions.
-Which two groups are most clearly represented in the Ediacaran fauna?

Accepted Answer

A) I and II 
B) I and III 
C) II and IV 
D) II and V 
E) IV and V 
A) I and II 
B) I and III 
C) II and IV 
D) II and V 
E) IV and V

Question 14

The larvae of some insects are merely small versions of the adult, whereas the larvae of other insects look completely different from adults, eat different foods, and may live in different habitats. Which of the following most directly favours the evolution of the latter, more radical, kind of metamorphosis?

Accepted Answer

A) natural selection of sexually immature forms of insects 
B) changes in the homeobox genes governing early development 
C) the evolution of meiosis 
D) the development of an oxidizing atmosphere on Earth 
E) the origin of a brain 
A) natural selection of sexually immature forms of insects 
B) changes in the homeobox genes governing early development 
C) the evolution of meiosis 
D) the development of an oxidizing atmosphere on Earth 
E) the origin of a brain

Question 15

Placozoan evolutionary relationships to other animals are currently unclear, and different phylogenies can be created, depending on the character used to infer relatedness. Sponges have no tissues, but about 20 cell types. Tp (Trichoplax adhaerens) produces a neuropeptide almost identical to one found in cnidarians. The genome of Tp, though the smallest of any known animal, shares many features of complex eumetazoan (even human!) genomes. Use the phylogenetic trees that follow to answer the questions below.
   
I
   
II
   
III
-Cycliophorans have two types of larvae. One type of larva-the Prometheus larva-develops into a male. The male, which lacks a digestive system, attaches to the outside of a feeding stage (a female)and impregnates her digestive system, which develops into a different type of larva. What must be true of the digestive system of the feeding-stage female while she is still a virgin? 1. At least some of its cells are haploid.
2. It consists only of highly specialized cells.
3. It is the same size as the male.

Accepted Answer

A) 1 only 
B) 2 only 
C) 3 only 
D) 1 and 3 
E) 2 and 3 
A) 1 only 
B) 2 only 
C) 3 only 
D) 1 and 3 
E) 2 and 3

Question 16

Placozoan evolutionary relationships to other animals are currently unclear, and different phylogenies can be created, depending on the character used to infer relatedness. Sponges have no tissues, but about 20 cell types. Tp (Trichoplax adhaerens) produces a neuropeptide almost identical to one found in cnidarians. The genome of Tp, though the smallest of any known animal, shares many features of complex eumetazoan (even human!) genomes. Use the phylogenetic trees that follow to answer the questions below.
   
I
   
II
   
III
-Which phylogeny has been created by emphasizing the structural simplicity of placozoans?

Accepted Answer

A) I 
B) II 
C) III 
A) I 
B) II 
C) III

Question 17

Use the following information to answer the questions below.
Trichoplax adhaerens (Tp) is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. They move using cilia, and any "edge" can lead. Tp feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. Tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.
-Tp's body symmetry seems to be most like that of

Accepted Answer

A) most sponges. 
B) cnidarians. 
C) worms. 
D) tetrapods. 
E) Two of the responses above are correct. 
A) most sponges. 
B) cnidarians. 
C) worms. 
D) tetrapods. 
E) Two of the responses above are correct.

Question 18

Use the following information to answer the questions below.
Trichoplax adhaerens (Tp) is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 μm high, are irregularly shaped, and consist of a total of about 2000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. They move using cilia, and any "edge" can lead. Tp feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. Tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage.
-If Tp sperm are observed by future researchers, how many chromosomes should be found in a Tp sperm nucleus?

Accepted Answer

A) 2 
B) 3 
C) 6 
D) 12 
A) 2 
B) 3 
C) 6 
D) 12

Question 19

What do animals as diverse as corals and monkeys have in common?

Accepted Answer

A) body cavity between body wall and digestive system 
B) number of embryonic tissue layers 
C) type of body symmetry 
D) presence of Hox genes 
E) degree of cephalization 
A) body cavity between body wall and digestive system 
B) number of embryonic tissue layers 
C) type of body symmetry 
D) presence of Hox genes 
E) degree of cephalization

Question 20

Use the following information to answer the questions below.
The most recently discovered phylum in the animal kingdom (1995) is the phylum Cycliophora. It includes three species of tiny organisms that live in large numbers on the outsides of the mouthparts and appendages of lobsters. The feeding stage permanently attaches to the lobster via an adhesive disk, and collects scraps of food from its host's feeding by capturing the scraps in a current created by a ring of cilia. The body is sac-like and has a U-shaped intestine that brings the anus close to the mouth. Cycliophorans are eucoelomate, do not moult (though their host does), and their embryos undergo spiral cleavage.
-What is true of the feeding stage of cycliophorans? 1. It is chemoheterotrophic.
2. It is sessile.
3. It captures food in a manner similar to that of animals with lophophores.
4. It has radial symmetry.

Accepted Answer

A) 1 and 2 
B) 1 and 3 
C) 2 and 4 
D) 1, 2, and 3 
E) 2, 3, and 4 
A) 1 and 2 
B) 1 and 3 
C) 2 and 4 
D) 1, 2, and 3 
E) 2, 3, and 4

Exam 32: An Overview of Animal Diversity

Whatever its ultimate cause(s), the Cambrian explosion is a prime example of

Evidence of which structure or characteristic would be most surprising to find among fossils of the Ediacaran fauna?

Which statement is most consistent with the hypothesis that the Cambrian explosion was caused by the rise of predator-prey relationships?

Which of the following traits differentiates animals from plants and fungi?

Protostome characteristics generally include which of the following?

Which of the following is descriptive of protostomes?

With the current molecular-based phylogeny in mind, rank the following from most inclusive to least inclusive. 1. ecdysozoan 2. protostome 3. eumetazoan 4. triploblastic

The figure above shows a chart of the animal kingdom set up as a modified phylogenetic tree. Use the diagram to answer the following questions. -Which two groups are most clearly represented in the Ediacaran fauna?

What do animals as diverse as corals and monkeys have in common?

Introduction: Evolution and Themes of Biology

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

From Gene to Protein

Regulation of Gene Expression

Viruses

Dna Tools and Biotechnology

Genomes and Their Evolution

Descent With Modification: a Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity Ii: the Evolution of Seed Plants

Fungi

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signalling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behaviour

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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