Question 1

Which statement about nematodes is true?

Accepted Answer

Nematodes are one of the most abundant of all animal groups, with estimates of over 1 million species.

Answer: None 
 None of the other statements are true. Nematodes have a flexible cuticle, move by thrashing their bodies, are unsegmented, and only some species are parasitic.

Question 2

One group of pogonophorans, a polychaete clade, lives thousands of meters below the ocean surface near deep-sea hydrothermal vents.Which of the following is least likely to be functionally related to these facts?

Accepted Answer

The answer of One group of pogonophorans, a polychaete clade,...

Question 3

Parasitic wormlike ecdysozoans with unciliated, pseudocoelomate bodies and an anus would be classified as _______.

Accepted Answer

The answer of Parasitic wormlike ecdysozoans with unciliated, pseudocoelomate bodies...

Question 4

Flatworms have no coelom.Gene sequencing shows that their closest relatives are the bryozoans (which are coelomate) and the rotifers (which are pseudocoelomate).Which of the following is a legitimate conclusion?

Accepted Answer

The correct conclusion cannot be drawn solely based on the presence or absence of a coelom and gene sequencing relationships among flatworms, bryozoans, and rotifers. The information provided does not definitively support any of the conclusions listed, as evolutionary relationships are complex and cannot be determined by a single characteristic or method alone.

Question 5

Ecdysozoans

Accepted Answer

Ecdysozoans are a diverse group of animals that share a common characteristic of having a cuticle, which is a tough, protective outer layer that is molted or shed periodically as the animal grows. This includes organisms such as nematodes, arthropods, and tardigrades. While some ecdysozoans, such as arthropods, do have a thick, hard exoskeleton composed of protein and chitin, not all members of the group share this feature, making option B and C incorrect. Similarly, not all ecdysozoans have jointed appendages, eliminating option E. Finally, ecdysozoans are not a polyphyletic group, as they are believed to share a common ancestor and are therefore considered a monophyletic group.

Question 6

The stage of the life cycle of Trichinella spiralis that has the greatest impact on humans is the _______.

Accepted Answer

The answer of The stage of the life cycle of...

Question 7

Which characteristic of bryozoans would indicate that they feed by sweeping a feeding organ through the water?

Accepted Answer

Bryozoans have lophophores, which are feeding structures used to sweep food particles out of the water. Therefore, the presence of lophophores would indicate that bryozoans feed by sweeping a feeding organ through the water. The other answer choices are not relevant to this characteristic.

Question 8

All oligochaetes

Accepted Answer

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

Question 9

A 500-million-year-old fossil from the Cambrian shows what appears to be a two mirror images of a marine invertebrate.This animal is likely an ancestral _______.

Accepted Answer

The answer of A 500-million-year-old fossil from the Cambrian shows...

Question 10

Annelids

Accepted Answer

Annelids have a coelom, which is a fluid-filled body cavity lined with mesoderm. This distinguishes them from acoelomates (lacking a coelom) and pseudocoelomates (having a partially lined coelom). Annelids have a well-developed segmented body plan, which is also unique to this phylum. They thrive in moist environments and possess a flexible, non-rigid cuticle.

Question 11

Phoronids

Accepted Answer

Phoronids secrete tubes made of chitin.

Question 12

Although lophotrochozoan species with spiral cleavage were once grouped together taxonomically as spiralians, gene sequence analysis does not support the spiralian taxon as monophyletic.What conclusion follows from this evidence?

Accepted Answer

The fact that gene sequence analysis does not support the spiralian taxon as monophyletic suggests that spiral cleavage may have been present in the lophotrochozoan ancestor, but that it has been lost in some lineages since the group originated.

Question 13

Parasitic flukes _______, and thus most of the body can be devoted to reproduction.

Accepted Answer

Parasitic flukes acquire all of their nutrients from their host, which allows the majority of the body to be devoted to reproduction.

Question 14

Arrow worms

Accepted Answer

Arrow worms were once suspected to be deuterostomes based on their embryonic development, but later studies showed that they are actually protostomes.

Answer: E
 Arrow worms have a distinct larval stage, called the nectochaete, which is a swimming stage that eventually metamorphoses into the adult form.

Therefore, the best choices are A and E.

Question 15

Which of the following is not a characteristic of lophotrochozoans?

Accepted Answer

A hemocoel is not a characteristic of lophotrochozoans.

Question 16

Bdelloid rotifers may have existed for tens of millions of years without regular sexual reproduction, though long-term asexual reproduction typically leads to extinction.Bdelloid rotifers acquire gene fragments from the environment during the desiccation-rehydration cycle.Which statement best explains their survival?

Accepted Answer

Acquiring gene fragments allows for genetic recombination, which introduces genetic diversity and can help in adapting to environmental changes, potentially explaining the survival of bdelloid rotifers despite their long-term asexual reproduction.

Question 17

Which statement about brachiopods is false?

Accepted Answer

Brachiopods are not bivalve mollusks, despite their superficial resemblance. They belong to a separate phylum called Brachiopoda.

Question 18

Which of the following about mollusks is false?

Accepted Answer

The mantle, not the visceral mass, secretes the shell in mollusks.

Question 19

If a specimen found in coarse marine sediments of the continental shelf measures 0.5 millimeters and has six cuticular plates, it is most likely a(n) _______.

Accepted Answer

The answer of If a specimen found in coarse marine...

Question 20

Which statement about protostomes is true?

Accepted Answer

The answer of Which statement about protostomes is true?
...

Quiz 31: Protostome Animals