Biology, Eighth Edition (Raven)

Chapter 19: Cellular Mechanisms of Development

Post Test

Which of the following is NOT one of the four subprocesses of overall development? (p. 370)
D)Pattern formation
Why are embryonic stem cells so enticing to researchers looking for solutions to many medical problems? (p. 372)
A)These cells can develop into any tissue in the animal.
B)Stem cells give rise to a single cell type, and so are predictable in culture.
C)These cells are easily obtained from the outer cell layer of a 5 day old embryo.
D)It is simple to alter the genetic content of these cells by use of microinjection or other technologies.
E)These cells are particularly sensitive to environmental cues and so can be coached into new, rarely expressed, developmental pathways.
What is the standard test for determination of cellular fate in an embryonic tissue? (p. 373)
A)Remove some cells and see if they form a new individual in a petri dish.
B)Place them next to undifferentiated cells and see whether these other cells change their developmental fate.
C)Introduce a new nucleus to the cells in question to see if they alter their developmental pathway.
D)Extract mRNA from the cell to see what kinds of gene expression have occurred.
E)Transplant cells from one end of an embryo to another and see if the structure which forms was consistent with the source location or the transplanted position.
In Drosophila, what is the result of underexpression of the Dorsal protein in developing dorsal mutants? (p. 384)
A)The embryos will not form appropriate ventral structures.
B)The dorsal/ ventral axis will be reversed.
C)Genes responsible for formation of ventral structure establishment will take over development.
D)Normal stimulation of the gurken genes by the Dorsal protein cannot occur.
E)Antigens against the Dorsal protein will uniformly label all cells of the mutant blastoderm stage embryos.
During gastrulation, cells take up different positions with respect to each other, eventually forming the primary germ layers. What happens if the extracellular matrix (ECM) is exposed to antibodies which adhere to fibronectins and integrins? (p. 390)
A)The cell would develop normally, although slowly.
B)An inflammation response would activate the immune system, which would clear away the antibodies to allow development to continue.
C)Cell migration would occur too quickly because the ECM would not hold together appropriately.
D)Cell proliferation would increase because the cells would drift apart, activating cell division programs which are repressed by high cell density.
E)Internalization of mesoderm would probably not occur.
Why drawback is there in the high use of C. elegans and Drosophila in developmental analysis? (p. 391)
A)Their regular and consistent development under laboratory conditions can lead to an underappreciation of the effects of the environment on development in wild organisms.
B)They are too small to be properly applied to real-life technological use.
C)They have such different genomes from other organisms that although we understand a lot about how they develop and grow, it has limited applicability to mammalian systems.
D)They only grow in the laboratory and therefore normal environmental influences cannot be investigated.
E)Natural selection does not operate on genes in laboratory animals. They therefore do not respond in a realistic way to experimentation.
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