General Biology Questions?

Question

1. Give two uses for a radula.

2. Distinguish between protostomes and deuterostomes.

3. What is the explanation for why deuterostomes became the largest animals on land and sea?

4. Which germ layers does a diploblastic animal have?

5. Give a human disease caused by a member of the Nematoda.

Answer 1

1. Radula is the scientific name for the toothed chitinous ribbon in the mouth of gastropods. They use it to graze and scrape diatoms and other microscopic algae off rock surfaces and other substrata.

2 . The major distinctions between deuterostomes and protostomes are found in embryonic development. In protostome development, the first opening in development, the blastopore, becomes its mouth. In deuterostome development, the blastopore becomes the animal's anus. Protostomes have what is known as spiral cleavage which is determinate, this meaning that the fate of the cells is determined as they are formed. This is in contrast to deuterostomes which have radial cleavage that is indeterminate.Another contrast resides in the formation of the coelom. Protostomes are schizocoelomates, meaning a solid mass of the embryonic mesoderm split to form a coelom. Deuterostomes are enterocoelous, meaning the folds of the archenteron for the coelom.

3. Deuterostomia ---- The Deuterostomia comprise the enterocoels—echinoderms, arrowworms, hemichordates, and chordates—the rest of the animal kingdom. These phyla are united mainly by developmental characteristics and may be related to the lophophorates, some of which also have an enterocoelous manner of forming the coelom. In addition, no segmentation exists of the sort found in annelids. Another important link of the deuterostomes to the lophophorates is the presence, in some members of both groups, of three pairs of coelomic cavities and three corresponding body regions. Adult deuterostomes have become quite modified. Thus, arrowworms are equipped for floating and swimming; echinoderms have lost their bilateral symmetry and reverted to radial symmetry (often with five rays, as in most starfish); the wormlike hemichordates have a very simple structure; and such advanced features as a complex brain and the capability for rapid locomotion evolved within the chordate lineage.

4 . Diploblasty is a condition of the ovum in which there are two primary germ layers: the ectoderm and endoderm.
Diploblastic organisms are organisms which evolve from such an ovum, and include cnidaria and ctenophores. The endoderm allows them to develop true tissue.

5 . Nematodes commonly parasitic on humans include whipworms-- is a roundworm, which causes trichuriasis when it infects a human large intestine.Hookworms--- causes anchylostomiasis . Pinworms--- causes enterobiasis .