¡¡¡¡£¨A£© Stimulates behavior in the mouse and in humans£¬ whereas adenosine stimulates behavior in humans only
¡¡¡¡£¨B£© has mixed effects in the brain£¬ whereas adenosine has only a stimulatory effect
¡¡¡¡£¨C£© increases cyclic AMP concentrations in target neurons£¬ whereas adenosine decreases such concentrations
¡¡¡¡£¨D£© permits release of neurotransmitters when it is bound to adenosine receptors£¬ whereas adenosine inhibits such release
¡¡¡¡£¨E£© inhibits both neuron firing and the production of phosphodiesterase when there is a sufficient concentration in the brain£¬ whereas adenosine inhibits only neuron firing
¡¡¡¡4. In response to experimental results concerning IBMX£¬ Snyder et al contended that it is not uncommon for psychoactive drugs to have
¡¡¡¡£¨A£© mixed effects in the brain
¡¡¡¡£¨B£© inhibitory effects on enzymes in the brain
¡¡¡¡£¨C£© close structural relationships with caffeine
¡¡¡¡£¨D£© depressive effects on mouse locomotion
¡¡¡¡£¨E£© the ability to dislodge caffeine from receptors in the brain
¡¡¡¡5. The passage suggests that Snyder et al believe that if the older theory concerning caffeine's effects were correct£¬ which of the following would have to be the case£¿
¡¡¡¡¢ñ¡£All neurotransmitters would increase the short-term concentration of cyclic AMP in target neurons.
¡¡¡¡¢ò¡£Substances other than caffeine that inhibit the production of phosphodiesterase would be stimulants.
¡¡¡¡¢ó¡£All concentration levels of caffeine that are high enough to produce stimulation would also inhibit the production of phosphodiesterase.
¡¡¡¡£¨A£© ¢ñ only
¡¡¡¡£¨B£© ¢ñ and ¢ò only
¡¡¡¡£¨C£© ¢ñand ¢ó only
¡¡¡¡£¨D£© ¢ò and ¢ó only
¡¡¡¡£¨E£© ¢ñ£¬¢ò£¬and ¢ó
¡¡¡¡6. According to Snyder et al£¬ all of the following compounds can bind to specific receptors in the brain EXCEPT
¡¡¡¡£¨A£© IBMX
¡¡¡¡£¨B£© caffeine
¡¡¡¡£¨C£© adenosine
¡¡¡¡£¨D£© theophylline
¡¡¡¡£¨E£© phosphodiesterase
¡¡¡¡7. Snyder et al suggest that caffeine's ability to bind to A1 and A2 receptors can be at least partially attributed to which of the following£¿
¡¡¡¡£¨A£© The chemical relationship between caffeine and phosphodiesterase
¡¡¡¡£¨B£© The structural relationship between caffeine and adenosine
¡¡¡¡£¨C£© The structural similarity between caffeine and neurotransmitters
¡¡¡¡£¨D£© The ability of caffeine to stimulate behavior
¡¡¡¡£¨E£© The natural occurrence of caffeine and adenosine in the brain
¡¡
