Which lineage of Echinoderms is made up of about 950 species of sea urchins and sand dollars, which have their ossicles fused into solid tests that restrict flexibility but provide excellent protection?

a. Holothuroidea
b. Crinoidea
c. Asteroidea
d. Echinoidea


Answer: d. Echinoidea

Biology & Microbiology

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The nutrition of some plants depends on a mutually beneficial association between a root and a fungus. The association is known as a _____

a. root nodule c. root hair b. mycorrhiza d. root hypha

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This animal has a pseudocoelom, is

unsegmented, a cuticle, and no circulatory system. This animal is ___.

a. a roundworm b. an earthworm c. a flatworm d. a leech e. more than one of these

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Which type of stem cell gives rise to red and white blood cells?

a. endothelial b. epithelial c. hematopoietic d. mesenchymal

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The scientific method starts with a(n)

A) hypothesis. B) proposal. C) question. D) observation. E) prediction.

Biology & Microbiology