Textbook Question
Propose an explanation for why annelids and arthropods were thought to be closely related, before phylogenetic analyses in the late 1990s.
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Ch. 31 - Protostome Animals
Freeman8th EditionBiological ScienceISBN: 9780138276263
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Table of contents
- Ch. 1 - Biology: The Study of Life13
- Ch. 2 - Water and Carbon: The Chemical Basis of Life14
- Ch.3 - Protein Structure and Function10
- Ch.4 - Nucleic Acids and the RNA World10
- Ch. 5 - An Introduction to Carbohydrates10
- Ch. 6 - Lipids, Membranes, and the First Cells11
- Ch. 7 - Inside the Cell10
- Ch. 8 - Energy and Enzymes: An Introduction to Metabolism10
- Ch. 9 - Cellular Respiration and Fermentation11
- Ch. 10 - Photosynthesis12
- Ch. 11 - Cell-Cell Interactions12
- Ch. 12 - The Cell Cycle8
- Ch. 13 - Meiosis12
- Ch. 14 - Mendel and the Gene23
- Ch. 15 - DNA and the Gene: Synthesis and Repair15
- Ch. 16 - How Genes Work16
- Ch. 17 - Transcription, RNA Processing, and Translation16
- Ch. 18 - Control of Gene Expression in Bacteria16
- Ch. 19 - Control of Gene Expression in Eukaryotes12
- Ch. 20 - The Molecular Revolution: Biotechnology, Genomics, and New Frontiers15
- Ch. 21 - Genes, Development, and Evolution12
- Ch. 22 - Evolution by Natural Selection16
- Ch. 23 - Evolutionary Processes13
- Ch. 24 - Speciation15
- Ch. 25 - Phylogenies and the History of Life13
- Ch. 26 - Bacteria and Archaea15
- Ch. 27 - Diversification of Eukaryotes16
- Ch. 28 - Green Algae and Land Plants16
- Ch. 29 - Fungi18
- Ch. 30 - An Introduction to Animals9
- Ch. 31 - Protostome Animals15
- Ch. 32 - Deuterostome Animals17
- Ch. 33 - Viruses16
- Ch. 34 - Plant Form and Function16
- Ch. 35 - Water and Sugar Transport in Plants16
- Ch. 36 - Plant Nutrition13
- Ch. 37 - Plant Sensory Systems, Signals, and Responses16
- Ch. 38 - Flowering Plant Reproduction and Development16
- Ch. 39 - Animal Form and Function17
- Ch. 40 - Water and Electrolyte Balance in Animals16
- Ch. 41 - Animal Nutrition16
- Ch. 42 - Gas Exchange and Circulation16
- Ch. 43 - Animal Nervous Systems16
- Ch. 44 - Animal Sensory Systems16
- Ch. 45 - Animal Movement11
- Ch. 46 - Chemical Signals in Animals16
- Ch. 47 - Animal Reproduction and Development16
- Ch. 48 - The Immune System in Animals16
- Ch. 49 - An Introduction to Ecology15
- Ch. 50 - Behavioral Ecology16
- Ch. 51 - Population Ecology16
- Ch. 52 - Community Ecology20
- Ch. 53 - Ecosystems and Global Ecology17
- Ch. 54 - Biodiversity and Conservation Ecology18
Chapter 31, Problem 8
Which of these choices is an example of homology (similarity due to common ancestry)?
a. Suspension feeding in sponges and clams
b. Ectoparasite lifestyle in aphids and ticks
c. Cnidocytes (stinging cells) in jellyfish and sea anemones
d. Radial symmetry in cnidarians and echinoderms
Verified step by step guidance1
Understand the concept of homology: Homology refers to similarities between organisms that arise from a common ancestor. These traits are inherited from a shared ancestor and may serve different functions in the descendants.
Analyze each choice to determine if the trait is due to common ancestry: For each option, consider whether the trait is likely inherited from a common ancestor or if it evolved independently.
Option a: Suspension feeding in sponges and clams. Consider the evolutionary history of sponges and clams. They belong to different phyla, and their suspension feeding mechanisms evolved independently, not due to common ancestry.
Option b: Ectoparasite lifestyle in aphids and ticks. Aphids and ticks are from different classes and have independently evolved to be ectoparasites, so this is not an example of homology.
Option c: Cnidocytes in jellyfish and sea anemones. Both jellyfish and sea anemones are part of the phylum Cnidaria, and cnidocytes are a characteristic feature of this phylum, indicating a common ancestry. This is an example of homology.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Homology
Homology refers to the similarity in characteristics resulting from shared ancestry. It is a fundamental concept in evolutionary biology, indicating that certain traits or structures in different species have evolved from a common ancestor. Homologous structures may serve different functions but share a similar underlying anatomy.
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Cnidocytes
Cnidocytes are specialized cells found in cnidarians, such as jellyfish and sea anemones, used for capturing prey and defense. These cells contain organelles called nematocysts, which can deliver a sting to potential threats or prey. The presence of cnidocytes in both jellyfish and sea anemones suggests a common evolutionary origin, making them an example of homology.
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Radial Symmetry
Radial symmetry is a form of symmetry where body parts are arranged around a central axis, common in organisms like cnidarians and echinoderms. While radial symmetry is a shared trait, it is not necessarily due to common ancestry, as it can arise independently in different evolutionary lineages. Thus, it is not an example of homology but rather convergent evolution.
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Related Practice
Textbook Question
Use your understanding of insect evolution to predict two adaptations for terrestrial living that occurred in spiders.
Textbook Question
Pose a hypothesis to explain why the evolution of the wing was such an important event in the evolution of insects.
Textbook Question
Evaluate this statement: Evolution is said to occur when new traits accumulate over time, increasing complexity.
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Textbook Question
A team of 102 scientists spent a year surveying a small area of the San Lorenzo rain forest in Panama to count the number of species of arthropods living there. After collecting 129,494 specimens—using nets, traps, shovels, tree-climbing harnesses, helium balloons, and other creative gear—it took the team eight years to sort and identify the arthropods. Which of the following nested groups best describes the taxonomic context for the San Lorenzo project?
a. Animalia > Bilateria > Arthropoda > Ecdysozoa
b. Protostomia > Lophotrochozoa > Ecdysozoa > Arthropoda
c. Arthropoda > Protostomia > Ecdysozoa > Bilateria
d. Bilateria > Protostomia > Ecdysozoa > Arthropoda