Removal of sea otters from a system results in a massive increase in sea urchins and subsequent loss of kelp beds. This is an example of
A) a trophic cascade.
B) apparent competition.
C) bottom-up control.
D) indirect mutualism.
A
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What is the primary determinant of airway resistance?
A) traction competency B) presence of mucous C) rate of air exchange D) compliance E) airway radius
An inflammation of the mucous membranes of the oral cavity caused mostly by herpes simplex virus is:
a. laryngitis. b. pharyngitis. c. Vincent angina. d. stomatitis.
All of the following are adaptations against excessive water and salt exchange between animals and their surrounding environment except:
a. having very permeable tissues. b. covering body with mucus. c. living inside a tube that can be isolated from the external environment. d. covering the body with a hard exoskeleton. e. actively absorbing salt ions with gills.
Which statement about the fate of progenitor cells in Caenorhabditis elegans is not correct?
A. The fate of progenitor cells is determined by their proximity to the anchor cell, which secretes epidermal growth factor. B. Epidermal growth factor binds and activates a transmembrane receptor protein in the cell nearest to the anchor cell. C. In the cell closest to the anchor cell, genes for differentiation into a type 1 cell are activated by epidermal growth factor binding to its receptor. D. Following epidermal growth factor receptor activation, the cell closest to anchor cell inhibits adjacent cells from differentiating to type 1 cells. E. Differentiating into a type 2 cell occurs spontaneously without the need for special genes for type 2 differentiation.