Item 2 Protostomes are categorized into two clades: Lophotrochozoa and Ecdysozoa

Question

Item 2

Protostomes are categorized into two clades: Lophotrochozoa and Ecdysozoa. Ecdysozoa includes about eight phyla, including the phyla Arthropoda and Nematoda. Arthropods and nematodes (roundworms) are among the most abundant of all animal groups.

The simplified evolutionary tree below shows the relationship between arthropods, nematodes, and lophotrochozoans. (There are more ecdysozoan phyla than shown on this tree.)

Part A - Comparing nematodes and arthropods

Nematodes and arthropods are the largest ecdysozoan phyla.

Which of the following statements are true?

Select all that apply.

Select all that apply.

Some nematodes are parasitic on humans. Arthropods are named for their jointed appendages. Nematodes are acoelomate, whereas arthropods are coelomate. Nematodes possess a closed circulatory system. The cuticle in nematodes lengthens as the animal grows. Both nematodes and arthropods must molt in order to increase in size. Both nematodes and arthropods have segmented body plans. Both nematodes and arthropods possess an external covering, or cuticle. Arthropods possess an open circulatory system.

Explanation / Answer

* Both nematodes and arthropods possess an external covering, or cuticle.
* Arthropods possess an open circulatory system.
* Some nematodes are parasitic on humans.
* Both nematodes and arthropods must molt in order to increase in size.
* Arthropods are named for their jointed appendages.

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