Why do some hormones need to trigger a "second messenger" to activate a target cell?
What will be an ideal response?
they cannot cross cell membranes
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The __________ prevents food and fluids from
entering the __________. a. epiglottis; larynx b. pharynx; larynx c. epiglottis; esophagus d. pharynx; trachea e. larynx; pharynx
Woese and his co-workers demonstrated that the Archaea were different from the Bacteria because of
differences noted in their:a. mechanism of cellular respiration. b. preferred habitats. c. signature sequences of SSU rRNA. d. ability to utilize oxygen.. e. resistance to antibiotics
If a plant is living under conditions that limit root growth, shoot growth is
A) limited as well, due to more auxin being produced by the apical meristem. B) unaffected by the amount of root growth. C) stimulated, due to more auxin being produced by the apical meristem. D) stimulated, due to less cytokinin being produced by the root. E) limited as well, due to less cytokinin being produced by the root.
All of the following are functions of the citric acid cycle except
A) production of ATP. B) production of NADH. C) production of FADH2. D) release of carbon dioxide. E) adding electrons and protons to oxygen, forming water.