Tutor profile: Hillary K.
According to Skinner's experiments in which he trained mice to press levers, which reinforcement schedule produced the lease amount of behavior extinction (the mice did not stop pressing the lever)? a) continuous reinforcement b) fixed ratio reinforcement c) fixed interval reinforcement d) variable ratio reinforcement
The answer is D-- variable ratio reinforcement a) Continuous Reinforcement-- positive reinforcement every time a specific behavior occurs (every time a lever is pressed a pellet is delivered, and then food delivery is shut off) Extinction rate is fast because the mouse is no longer being rewarded for the behavior b) Fixed Ratio Reinforcement-- behavior is reinforced only after the behavior occurs a specified number of times (reinforcement is given after every so many correct responses-- every 5th correct behavioral response) Extinction rate is medium c) Fixed Interval Reinforcement-- one reinforcement is given after a fixed time interval as long as at least one correct response has been made. An example would be every 15 minutes a pellet of food is delivered to the mouse (providing at least one lever press has been made) then food delivery is shut off Extinction rate is medium d) Variable Ratio Reinforcement-- behavior is reinforced after an unpredictable number of times. Extinction of the behavior is rate is slow (very hard to get rid of because of the reward unpredictability, the mouse will keep pressing the level thinking the next time will be the time he gets food)
Oxidative phosphorylation is the pathway necessary to allow cells to derive energy from food. Which of the following enzymes is not involved in oxidative phosphorylation? a) ATP synthase b) Succinate dehydrogenase c) Cytochrome C Oxidase d) Lactate dehydrogenase
The answer is D. Lactate dehydrogenase catalyzes the reversible conversion of lactate to pyruvate. This enzyme is mainly used in the muscles when oxygen supplies are low in anaerobic metabolism when oxidative phosphorylation cannot be carried out. All of the other enzymes are used in oxidative phosphorylation.
Loss of function of which nerve would result in inability to dorsiflex the foot (a problem known as foot drop)? a) tibial nerve b) deep fibular nerve c) sural nerve d) femoral nerve
This question has two steps to solve it. The first step to answering this question is to figure out which muscle dorsiflexes the foot--the tibialis anterior muscle. Then, you must figure out which listed nerve innervates the tibialis anterior--the deep fibular nerve (choice B). Another way to solve to solve this question is to go through what each listed nerve innervates: a) tibial nerve--posterior lower leg compartment and doesn't supply the tibialis anterior c) sural nerve--no motor innervation, it is a sensory nerve d) femoral nerve-- supplies skin on upper thigh and inner leg and supplies muscles in upper leg that extend the knee
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