Question 1

Which of the following is a key characteristic that distinguishes protostomes from deuterostomes during embryonic development?

Accepted Answer

Protostomes develop the mouth from the blastopore, while deuterostomes develop the anus from the blastopore.

Question 2

Which of the following phyla is considered the most basal animal taxon and shares key characteristics with choanoflagellates?

Accepted Answer

Porifera

Question 3

A marine biologist discovers an animal with a segmented body, parapodia with many setae, and jaws. Which phylum and group does this animal most likely belong to?

Accepted Answer

Phylum Annelida, Errantians

Question 4

Which of the following is NOT a function of the mantle in mollusks?

Accepted Answer

Producing digestive enzymes for the gut

Question 5

Which of the following groups of mollusks is characterized by a closed circulatory system and highly developed nervous system?

Accepted Answer

Cephalopoda

Question 6

Which of the following statements about nematodes is TRUE?

Accepted Answer

They possess only longitudinal muscles and move by thrashing.

Question 7

Which of the following adaptations allowed protostomes to successfully transition from aquatic to terrestrial environments?

Accepted Answer

Development of hydrostatic skeletons, exoskeletons, and appendages

Question 8

A scientist is studying an animal with two tagmata, chelicerae, and no antennae. Which group does this animal most likely belong to?

Accepted Answer

Chelicerata

Question 9

Which of the following is a major difference between lophotrochozoans and ecdysozoans?

Accepted Answer

Lophotrochozoans grow incrementally, while ecdysozoans grow by molting their exoskeleton.

Question 10

Which of the following equations best represents the relationship between surface area ($$A) $$and volume ($$V) $$for a spherical animal, and why is this relationship important for gas exchange in small aquatic protostomes?

Accepted Answer

$$A = 4 \pi r^2$, V$$ = \frac{4}{3} \pi $$r^3$$; a high surface area to volume ratio facilitates efficient gas exchange by diffusion.

Question 11

Which of the following is a reproductive innovation found in protostomes that increases survival in terrestrial environments?

Accepted Answer

Desiccation-resistant eggs

Question 12

Which of the following groups of arthropods is characterized by three tagmata, six legs, and the ability to fly?

Accepted Answer

Hexapoda (Insects)

Question 13

A patient is diagnosed with a parasitic infection caused by an animal with a tube-within-a-tube body plan, no appendages, and a cuticle. Which phylum is the parasite most likely from?

Accepted Answer

Nematoda

Question 14

Which of the following feeding strategies is NOT found among protostomes?

Accepted Answer

Photosynthetic feeding

Question 15

Which of the following is a correct pairing of a molluscan group and its main characteristic?

Accepted Answer

Bivalvia: hinged left and right shells, lack radula

Question 16

Which of the following is a major evolutionary trend in arthropod evolution?

Accepted Answer

Decreasing segment number and increasing appendage specialization

Question 17

Which of the following statements about earthworms is TRUE?

Accepted Answer

They enrich soil with castings and aerate soil through burrowing.

Question 18

Which of the following is a characteristic of chelicerate arthropods?

Accepted Answer

Presence of chelicerae and lack of antennae

Question 19

Which of the following is a correct description of the body plan found in most worm-like protostome phyla?

Accepted Answer

Tube-within-a-tube design with ectoderm-derived skin and endoderm-derived gut

Protostome Animals: Diversity, Phylogeny, and Major Groups

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