Ch. 33 - An introduction to Invertebrates

Campbell - Campbell Biology 12th Edition

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Urry 12th Edition

Ch. 33 - An introduction to Invertebrates

Problema 4

Capitolo 33, Problema 4

Which of the following combinations of phylum and description is correct?
a. Echinodermata—radial symmetry as a larva, coelom
b. Nematoda—roundworms, internal skeleton
c. Platyhelminthes—flatworms, gastrovascular cavity, no body cavity
d. Porifera—gastrovascular cavity, coelom

Guida verificata passo dopo passo

Step 1: Understand the question. The problem asks to identify the correct combination of a phylum and its description. Each option pairs a phylum with specific characteristics. We need to evaluate each option based on biological knowledge of these phyla.

Step 2: Analyze option (A) - Echinodermata. Echinoderms (e.g., sea stars) exhibit bilateral symmetry as larvae and radial symmetry as adults. They also have a coelom, which is a body cavity. This description is partially correct, but note the symmetry changes during development.

Step 3: Analyze option (B) - Nematoda. Nematodes (roundworms) are pseudocoelomates, meaning they have a body cavity that is not fully lined with mesoderm. They do not have an internal skeleton; instead, they have a hydrostatic skeleton. This description is incorrect.

Step 4: Analyze option (C) - Platyhelminthes. Flatworms are acoelomates, meaning they lack a body cavity. They have a gastrovascular cavity for digestion. This description is correct as it matches the characteristics of Platyhelminthes.

Step 5: Analyze option (D) - Porifera. Sponges (Porifera) lack a gastrovascular cavity and a coelom. They rely on water flow through their porous bodies for nutrient and waste exchange. This description is incorrect. Based on the analysis, option (C) is the correct combination.

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Echinodermata

Echinodermata is a phylum of marine animals characterized by radial symmetry in adults and bilateral symmetry in larvae. They possess a coelom, which is a fluid-filled body cavity, and are known for their unique water vascular system that aids in movement and feeding. Common examples include starfish and sea urchins.

Nematoda

Nematoda, or roundworms, are a phylum of unsegmented worms that have a complete digestive system and a pseudocoelom, which is a body cavity not entirely lined by mesoderm. They lack an internal skeleton and are found in various environments, including soil and aquatic habitats. Many nematodes are important in ecosystems and some are parasitic.

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02:05

Nematodes

Platyhelminthes

Platyhelminthes, commonly known as flatworms, are a phylum of soft-bodied invertebrates that exhibit bilateral symmetry and are characterized by their flattened bodies. They possess a gastrovascular cavity, which serves both digestive and circulatory functions, but lack a true coelom. Examples include planarians, flukes, and tapeworms.

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11:32

Lophotrochozoans

Pratica correlata

Domanda del libro di testo

In the following figure, which two main clades branch from the most recent common ancestor of the eumetazoans?

a. Porifera and Cnidaria

b. Lophotrochozoa and Ecdysozoa

c. Cnidaria and Bilateria

d. Deuterostomia and Bilateria

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Domanda del libro di testo

In Figure 33.7, assume that the two medusae shown at step 4 were produced by one polyp colony. Review Concept 12.1 and Concept 13.3, and then use your understanding of mitosis and meiosis to select which of the following is true.

a. Both the medusae and the gametes are genetically identical.

b. Neither the medusae nor the gametes are genetically identical.

c. The medusae are not genetically identical but the gametes are genetically identical.

d. The medusae are genetically identical but the gametes differ genetically.

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Domanda del libro di testo

The water vascular system of echinoderms

a. Functions as a circulatory system that distributes nutrients to body cells

b. Functions in locomotion and feeding

c. Is bilateral in organization, even though the adult animal is not bilaterally symmetrical

d. Moves water through the animal's body during filter feeding