Explanation:
Echinoderms belong to a very diverse phylum of marine-dwelling invertebrates, which have integral roles in salt water aquatic ecosystems. They comprise brittle stars, starfish, sea-urchins, sand dollars, and sea cucumbers. They have distinct characteristics, they:
- are only marine animals.
- show bilateral symmetry as larvae, and radial symmetry as adults
- show three layers (germ)
- show complex-level organisation, i.e. organs are seen
- have a fluid-filled body cavity
Learn more about other phyla at brainly.com/question/9504034
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Answer: C. Oxygen delivery to muscle is increased when more carbon dioxide is produced by the muscle.
Explanation:
When someone is doing an exercise, for example, his heart rate increases. This increases the rate at which oxygen is carried from the blood to the muscles and carbon dioxide is moved from the muscles to the lungs, where it will be breathed out.
This is because the GP120 protein
of the HIV virus that forms the ‘knob’ is
essential for the infection of CD4 cells
of the immune system by the virus. The glycoprotein is, therefore, a good
target for vaccines especially since the
molecule is highly conserved because most mutations in the region could be highly deleterious to the virus.