Taenia shows pseudometamerism, that is A) Segmentation where youngest segment is posterior most B) Segmentation where youngest segment is anterior most C) Segmentation where youngest segment is at the middle D) None of the above
Hint:Taenia is the genus of tapeworm which is an important parasite of livestock. It is responsible for taeniasis and cysticercosis in humans, that is helminthiasis.
Complete answer: ->Metamerism is defined as the structural similar segment present in the animal body. Although, not all segments are the same as some segments performing different functions. Every segment of the animal body is called the metamers. ->Metamerism is further divided into types: >Homonymous metamery :True metamerism and Pseudometamerism >Heteronomous metamery ->is present on the cestoda. ->Tapeworm contains so many repeating segments for basic nutrient requirements and for reproduction. ->Each segment in the tapeworm body works entirely different from one another. Segmentation in tapeworm is occurring by segmentation of ectoderm. ->The similar units of tapeworm body form eggs which cause infection while released in the environment. ->Pseudometamerism has the arrangement of internal organs without external metamerism where the every new segment formed at the anterior end, behind the scolex. Whereas, the youngest segments at the anterior end and the old segments at the posterior end.
Hence option B is the correct answer.
Note:There are so many species of genus Taenia.Segmentation basically occurs when an animal has growth.