1 Nicotine would the rate at which sodium ions Na enter the

[1] Nicotine would _______the rate at which sodium ions (Na⁺) enter the post-synaptic neuron (after the synapse) through sodium channels.

a) increase         b) decrease          c) have no effect on.

2. Addition of nicotine to a synapse would result in ___ activity (action potentials/neurotransmitter release) at the pre-synaptic membrane and _____ activity (action potentials) at the post-synaptic membrane.                                            

a) more, more                                                                                                                                           b) more, less                                                                                                                                                                   c) the same, more                                                                                                                                     d) the same, less                                                                                                                                                                    e) the same, the same                                                                                                                                                                    

3. What would you correctly predict about the insects that die because they eat tobacco?                                                                                                                                                   

a) All those that die would appear first to have seizures.                                                              b) All those that die would appear first to be paralyzed.                                                                                c) Some of those that die would first appear to be paralyzed and others would randomly appear to have seizures first.                                                                                                                                     d) They would have neither paralysis nor seizures prior to death.

4. Atropine (in an extract from the belladonna plant) was used by many Renaissance ladies (like Mona Lisa) as a beauty aid to enlarge their pupils. It acted by relaxing the muscles of the iris that control pupil size. Today, the military uses atropine as the antidote of choice against the lethal nerve gas sarin. You would hypothesize that sarin gas acts as an inhibitor of…

a) acetylcholine binding to receptors

b) acetylcholine breakdown

c) acetylcholine release

d) Na⁺ channel opening

e) K⁺ channel opening

5. A 20-acre field of mature belladonna plants in Sicily was subject to gale force winds in late autumn, randomly dispersing seeds downwind. The following spring, botanists sampled belladonna plants from one-acre plots east, northeast and southeast of the original field—none of which had grazing animals. The botanists noted that the plants in the northeastern plot average a higher amount of atropine per plant that from the other locations. Assuming all windblown seeds developed into plants, you would correctly hypothesize that their observation was a consequence of__.

a) coevolution

b) natural selection

c) the founder effect

d) thermoregulation

e) adaptive radiation

6. Following an action potential, if ATP is no longer available in the axon of a nerve, you would predict that…

a) subsequent action potentials would occur more frequently.

b) the sodium ion (Na⁺) channel would not close.

c) the axon would not return to resting potential.

d) a sodium ion (Na⁺) gradient would rapidly reform.

e) the Na⁺/ K⁺ (ATPase) pump would increase the rate of Na⁺ pumping.

7. When puffer fish toxin binds to Na⁺ channels, blocking them open on the victim’s axon membranes, what immediate sequence of events would you predict?

a) failure to release neurotransmitter, action potential inhibition in axon; muscle paralysis

b) failure to release neurotransmitter; action potential inhibition in axon; muscle spasms

c) action potential inhibition in axon; failure to release neurotransmitter; muscle paralysis

d) action potential inhibition in axon; failure to release neurotransmitter; muscle spasms

e) Na⁺ K⁺ (ATPase) pump inhibition; failure to release neurotransmitter; muscle paralysis

8. Other potent drugs that act at the neuromuscular junction (NMJ = the synapse between the neuron and muscle) have been used in medicine. One such paralytic drug, curare, is derived naturally from the tropical vine plant Strychnos toxifera. Although it has been smeared on arrowheads by indigenous hunter-warriors in the Amazon, curare in dilute form has medicinal value. It has been added to the anesthetic “cocktail” prescribed by surgeons as a muscle relaxant used prior to surgery. You would correctly hypothesize that the presence of curare…

a) enhanced the fitness of Strychnos toxifera.

b) is an adaptation Strychnos toxifera developed to avoid extinction.

c) is acquired by a new mutation only when insects start to eat Strychnos toxifera.

d) will someday be present in all rapidly growing plants.

e) all of the above

Solution

1. A) increases

2. B) more and more

3.

4. b) acetylcholine breakdown

5. E) adaptive radiation

6. c) the axon would not return to resting potential.

7. e) Na+ K+ (ATPase) pump inhibition; failure to release neurotransmitter; muscle paralysis

8. a) enhanced the fitness of Strychnos toxifera.