Question 1

Scientists have not found a fossilized body of the species that is the common ancestor of all bilaterally symmetrical animals. What is the likelihood that they will do so? How have scientists been able to learn about this common ancestor?

Accepted Answer

The answer of Scientists have not found a fossilized body...

Question 2

Which of the following statements about ectoprocts (bryozoans) is false?

Accepted Answer

A colony of ectoprocts grows by asexual reproduction, not sexual reproduction.

Question 3

Annelids

Accepted Answer

Annelids are known for having a coelom, which is a fluid-filled body cavity surrounded by mesodermal tissue. This allows for better circulation and movement. Annelids also have segmented bodies, which are important for flexibility and mobility. They are not adapted to dry environments and do not have a rigid exterior coating like arthropods. They are lophotrochozoans, which means they share certain developmental and genetic characteristics with other organisms within that group.

Question 4

Which of the following traits is not found in lophotrochozoans?

Accepted Answer

Lophotrochozoans have a complete digestive tract, with a separate mouth and anus.

Question 5

One clade of polychaetes, the pogonophorans,

Accepted Answer

Pogonophorans, also known as beard worms, lack a digestive tract and rely on symbiotic bacteria that can oxidize hydrogen sulfide for nutrition.

Question 6

The following are all characteristics of earthworms: segmented bodies, a spiral cleavage pattern, a terrestrial lifestyle, a complete gut, a blastopore that develops into a mouth, tight junctions between cells, and bilateral symmetry. In what order did these characteristics evolve?

Accepted Answer

The answer of The following are all characteristics of earthworms:...

Question 7

Which of the following statements about brachiopods is false?

Accepted Answer

Brachiopods are not bivalve mollusks, they are a distinct phylum of marine organisms with a dorsal and ventral shell and a lophophore for filter feeding. Bivalve mollusks, such as clams and oysters, have two shells that are hinged together.

Question 8

A thick cuticle provides an animal with protection, but it also can seal it off from the world, obstructing the exchange of gases. How would you design a simple, hypothetical animal with a covering that both provided protection and allowed gas exchange?

Accepted Answer

The answer of A thick cuticle provides an animal with...

Question 9

Why can parasitic flukes of vertebrates devote most of their bodies to reproduction?

Accepted Answer

Parasitic flukes of vertebrates obtain all of their nutrients from their host and therefore do not need to develop complex digestive tracts or a highly developed nervous system. This allows them to divert most of their energy towards reproduction. Additionally, they are often able to directly access the host's reproductive organs, further facilitating their reproductive success.

Question 10

Arrow worms

Accepted Answer

Arrow worms were previously thought to be deuterostomes based on their early development, but molecular evidence has shown that they are actually more closely related to the protostomes.

Answer: B
 Arrow worms have a circulatory system, with a dorsal and ventral vessel that runs the length of their body.

Answer: None of the choices (C, D, E) are best as they are all incorrect.

Overall, the best choice is A (since it is correct), but it is also important to note that B is also correct.

Question 11

Spiral cleavage in early development

Accepted Answer

The answer of Spiral cleavage in early development
...

Question 12

Based on their body _______, flatworms, rotifers, and ribbon worms were not thought to be closely related. However, _______ showed that they are a _______ group.

Accepted Answer

Flatworms, rotifers, and ribbon worms have different body cavities and were previously thought to be unrelated. However, gene sequencing studies have shown that they share a common ancestor and are a monophyletic group. Therefore, the correct answer is option B, which reflects this information. Options A and D are incorrect because flatworms, rotifers, and ribbon worms do not have similar body plans. Option C is incorrect because they are not polyphyletic. Option E is incorrect because they are a monophyletic group.

Question 13

The letters pter occur in the names of many insect groups. Can you discover the Greek word that is the root of this nomenclature? (Hint: The same word is the root name for a well-known dinosaur group, the pterodactyls.) Most good dictionaries give the meanings of word prefixes and roots; using such a dictionary, determine the meaning of the following names of insect groups:
Apterygota
Ephemeroptera
Orthoptera
Isoptera
Hemiptera
Homoptera
Coleoptera
Trichoptera
Lepidoptera
Diptera
Hymenoptera
Siphonaptera

Accepted Answer

The answer of The letters pter occur in the names...

Question 14

The mollusks are a very diverse group morphologically, but they share three common morphological traits. Describe these traits and their functions.

Accepted Answer

The answer of The mollusks are a very diverse group...

Question 15

All protostomes

Accepted Answer

All protostomes have mesoderm, which gives rise to various structures such as muscles, internal organs, and connective tissue. The other options are not true for all protostomes, as some may form a mouth from the blastopore (e.g. mollusks), have an anus separate from the blastopore (e.g. annelids), lack a true coelom (e.g. flatworms), or have diverse body plans (e.g. arthropods vs. mollusks).

Question 16

All oligochaetes

Accepted Answer

Oligochaetes are hermaphrodites, meaning they have both male and female reproductive organs.

Question 17

Phoronids

Accepted Answer

Phoronids are tube-dwelling marine animals that secrete tubes made of chitin.

Question 18

Which of the following statements about rotifers is true?

Accepted Answer

Bdelloid rotifers are known for reproducing exclusively through asexual means, specifically parthenogenesis.

Question 19

Ecdysozoans

Accepted Answer

Ecdysozoans are a monophyletic group characterized by their ability to molt or shed their exoskeletons through a process called ecdysis. This exoskeleton, also called a cuticle, is composed of protein and chitin. Not all ecdysozoans have a thick, hard exoskeleton, nor do they all have jointed appendages. However, they do all share the trait of having a cuticle.

Question 20

Which of the following attributes is not seen in the arthropod body plan?

Accepted Answer

Arthropods have an open circulatory system, not a closed circulatory system.

Quiz 32: Protostome Animals