Oxytocin and cholecystokinin are transported through the bloodstream and arrive at the uterus at the same time. Oxytocin causes the uterus to contract, whereas cholecystokinin has no effect. Why?
A. The uterus has receptors for oxytocin, but
not for cholecystokinin.
B. Oxytocin blocks the activity of
cholecystokinin.
C. Oxytocin alters gene expression patterns,
whereas cholecystokinin does not.
D. Oxytocin is able to diffuse through the
plasma membrane of uterine cells, whereas
cholecystokinin cannot.
E. Oxytocin is at a higher concentration in the
bloodstream than cholecystokinin.
A
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Which one of the following statements about RNA is incorrect?
A. The nucleotide at the 5' end of an RNA molecule is typically a nucleoside triphosphate. B. RNA is usually found in double-stranded form, just like DNA. C. RNA molecules are typically shorter than DNA molecules. D. RNA molecules can form base pairs within a single strand. E. RNA molecules are capable of evolving their enzymatic activity over time.
Which of the following organisms has the largest brain compared to their body size?
A. elephants B. blue whales C. gorillas D. humans E. goldfish
The biological species concept of Ernst Mayr cannot be applied to
A. sympatric organisms. B. allopatric organisms. C. eukaryotic organisms. D. prokaryotic organisms. E. asexually-reproducing organisms.
The hypothalamus and pituitary link the activities of the endocrine system and nervous system by
a. neurohormones being secreted in response to the summation of neural messages that enter the hypothalamus. b. shifts in hormonal concentrations being detected by the anterior pituitary. c. pheromones being secreted as a response to photoperiodic stimuli. d. the nervous tissue of the anterior lobe of the pituitary sending stimuli to the glandular tissue of the posterior pituitary to produce hormones that will be secreted by the hypothalamus. e. direct neural connections.