Mutations in which of the following genes lead to transformations in the identity of entire body parts?
A) morphogens
B) segmentation genes
C) egg-polarity genes
D) homeotic genes
E) inducers
Answer: D
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In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores
Afterward, the capsids go from being full to being "empty." Which of the following best fits these observations? A) Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus. B) The viral envelope is not required for infectivity, since the envelope does not enter the nucleus. C) Only the genetic material of the virus is involved in the cell's infectivity, and is injected like the genome of a phage. D) The viral envelope mediates entry into the cell, the capsid mediates entry into the nuclear membrane, and the genome is all that enters the nucleus. E) The viral capsid mediates entry into the cell, and only the genomic DNA enters the nucleus, where it may or may not replicate.
The ecological niche of a plant in your yard includes (select all that apply)
A. the pH of its soil. B. the insects that eat it. C. the tree that shades it. D. the depth to which the soil freezes in the winter. E. none of these.
Which of the following choices regarding fixed action patterns is incorrect?
a) A fixed action pattern can be potentially maladaptive. b) Fixed action patterns are innate behaviors. c) Once it is triggered, a counter-stimulus could halt a fixed action pattern. d) Fixed action patterns require no learning. e) A fixed action pattern of one organism can be exploited for the benefit of another.
Helper T cells activate both B cells and cytotoxic T cells.
Answer the following statement true (T) or false (F)