Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

31. Invertebrates

Ecdysozoans

General Biology

31. Invertebrates

Ecdysozoans

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1:34 minutes

Problem 7

Textbook Question

Molecular comparisons place nematodes and arthropods in clade Ecdysozoa. What characteristic do they share that is the basis for the name Ecdysozoa?
a. A complete digestive tract
b. Body segmentation
c. Molting of an exoskeleton
d. Bilateral symmetry

Verified step by step guidance

Understand the term 'Ecdysozoa': This clade includes organisms that undergo ecdysis, which is the process of molting or shedding their outer covering (exoskeleton) as they grow.

Review the characteristics of nematodes and arthropods: Both groups are known to have an external covering. Nematodes have a cuticle, while arthropods have a more rigid exoskeleton.

Connect the process of molting to the clade name: The term 'Ecdysozoa' is derived from 'ecdysis,' which refers to the shedding of the exoskeleton or cuticle. This is a defining feature of this clade.

Analyze the answer choices: a) A complete digestive tract is not unique to Ecdysozoa, as many other organisms also have this feature. b) Body segmentation is a characteristic of arthropods but not nematodes. c) Molting of an exoskeleton is directly tied to the process of ecdysis, which defines the clade. d) Bilateral symmetry is a common feature in many animal groups, not specific to Ecdysozoa.

Select the correct answer: Based on the shared characteristic of molting, the correct answer is c) molting of an exoskeleton.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ecdysozoa

Ecdysozoa is a clade of animals characterized by their ability to molt, or shed their exoskeleton. This process, known as ecdysis, allows for growth and development in organisms that have a rigid outer covering. Nematodes (roundworms) and arthropods (insects, crustaceans, etc.) are key members of this group, highlighting the evolutionary significance of molting in adapting to various environments.

Molting

Molting is the biological process through which certain animals, particularly those in the Ecdysozoa clade, periodically shed their exoskeleton or cuticle. This process is crucial for growth, as the rigid exoskeleton does not expand. After molting, the new exoskeleton is initially soft and allows for further growth before hardening, which is essential for the survival and development of these organisms.

Exoskeleton

An exoskeleton is a hard outer structure that provides support and protection to certain animals, including arthropods and some other invertebrates. Unlike an endoskeleton, which is internal, the exoskeleton must be periodically shed through molting to allow for growth. This feature is a defining characteristic of the Ecdysozoa clade, emphasizing the evolutionary adaptations that facilitate survival in diverse habitats.

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Molecular comparisons place nematodes and arthropods in clade Ecdysozoa. What characteristic do they share that is the basis for the name Ecdysozoa? a. A complete digestive tract b. Body segmentation c. Molting of an exoskeleton d. Bilateral symmetry

Key Concepts

Ecdysozoa

Molting

Exoskeleton

Watch next

Molecular comparisons place nematodes and arthropods in clade Ecdysozoa. What characteristic do they share that is the basis for the name Ecdysozoa?
a. A complete digestive tract
b. Body segmentation
c. Molting of an exoskeleton
d. Bilateral symmetry