There are cases, particularly in fruit flies, in which a normal body part grows in the wrong spot. For instance, legs on the head growing instead of antennae, or a second set of wings behind the normal pair. What can explain this?
A. These are due to the reappearance of stem cells, which are totipotent.
B. These are due to misregulation of hormones from environmental contamination with pesticides.
C. These occur as a result of mutations in homeotic genes, which normally act to direct development along the anterior-posterior axis.
D. These naturally occur sometimes in animals that have metamorphic development, due to different organization of homeotic gene expression in larvae versus adults.
C. These occur as a result of mutations in homeotic genes, which normally act to direct development along the anterior-posterior axis.
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Mendel’s theory of independent assortment states
that a. one allele is always dominant to another. b. hereditary units from the male and female parents are blended in the offspring. c. the two hereditary units that influence a certain trait segregate during gamete formation. d. each hereditary unit is inherited separately from other hereditary units. e. all of these are true.
The theory that a severe drought was responsible for
the disappearance of the Jamestown colony and the hardships of the Virginia colony came from evidence a. that showed corn from plants grown during that time. b. that showed the trees completely lacked growth rings. c. that showed Cypress trees from both colonies experienced low growth. d. from witnesses from both colonies. e. none of these.
Short, hairlike structures used only by eukaryotic cells for movement are called
A) pili. B) flagella. C) fimbriae. D) pseudopodia. E) cilia.
Microscopic examination of a lung biopsy shows thick-walled cysts. What is the etiology of the symptoms?
A) Blastomyces B) Coccidioides C) Histoplasma D) Mycobacterium E) Pneumocystis