Exam 7: Animal Growth and Development

Which of the following is incorrectly paired?

Which of the following organisms could result from a developing embryo where the mouth develops second?

Caenorhabditis elegans is a nematode with an adult body length of approximately 1 mm. It is a free-living organism that lives in temperate soil environments. It has played a major role as a model organism for research into molecular and developmental biology. This nematode lives for about 2-3 weeks and passes through four juvenile stages before reaching sexual maturity. It has six chromosomes and a transparent body that facilitates the study of cell differentiation and development. C. elegans has been used extensively in the study of aging. In these studies, scientists have discovered a gene called daf-2, which plays a significant role in controlling the aging process and longevity. In fertile nematodes where there is a mutation in the daf-2 gene, animals lived for almost twice as long as animals with the normal gene. The daf-2 gene produces molecules that play an important role in cell signaling pathways associated with growth and aging of individual cells. Reducing the activity of these molecules extends the life span of the whole animal. A mutation in the DNA of C. elegans means ____________________.

Caenorhabditis elegans is a nematode with an adult body length of approximately 1 mm. It is a free-living organism that lives in temperate soil environments. It has played a major role as a model organism for research into molecular and developmental biology. This nematode lives for about 2-3 weeks and passes through four juvenile stages before reaching sexual maturity. It has six chromosomes and a transparent body that facilitates the study of cell differentiation and development. C. elegans has been used extensively in the study of aging. In these studies, scientists have discovered a gene called daf-2, which plays a significant role in controlling the aging process and longevity. In fertile nematodes where there is a mutation in the daf-2 gene, animals lived for almost twice as long as animals with the normal gene. The daf-2 gene produces molecules that play an important role in cell signaling pathways associated with growth and aging of individual cells. Reducing the activity of these molecules extends the life span of the whole animal. Nematodes have an outer nonliving layer called a cuticle that must shed as the animal passes from one juvenile stage to the next. This cuticle is produced by the epidermal cells that originate from which germ layer?