Biology 305 Laboratory Midterm Exam Spring 2009 KEY Name: _______________________________ Day of Lab:_______________________Anyone caught cheating or aiding another in cheating will have their exam confiscated immediately and will be given a score of zero. In addition, further action will be pursued through UMBC’s Academic Conduct Committee and/or the Office of the Provost as described in the Policy for Academic Misconduct in Undergraduate Courses.Adaptation is the process by which a sensory system becomes less sensitive to stimuli during prolonged or repeated stimulation. Ringers solution is the name of the fluid used to keep tissue hydrated and maintain conductance. Rana pipiens is the scientific name of the leopard frog.In lab, the crayfish abdomen was curled _______________ to induce stretch in the _________________________________.Ventrally, superficial extensor muscleIf you apply 60 stimuli at a rate of 5 Hz, over what period of time would these stimuli be applied?12 secondsPlease view the diagram of the sciatic nerve preparation (below). Pay close attention to theposition of the electrodes, including the ground, which are connected to the nerve bath at the pins indicated (pins are numbered on the bath). Leads are labeled positive (+) and negative (–) as well as stimulating and recording. The nerve is pictured as the thick line within the nerve bath chamber.To determine conduction velocity, you decide to create a “short path” by changing the electrode configuration from the one pictured above. Which of the following would be consistent with creating this “short path”?Move the negative stimulating electrode to Pin #6 and the positive stimulating electrode to Pin #7Once you’ve determined that the nerve conducts in one direction, you want to show that it conducts bidirectionally. How would you go about doing this?Perform C and D onlyList THREE factors that influence the rate of action potential propagation in a single neuron. Accept any of the following (2 pts. each for a total of 6 pts):- Temperature- Presence of meylination- Length of axon- Diameter of axon5 6 7 8 91 2 3 4++Recording ElectrodeStimulating Electrode -- --GroundList THREE properties of fast twitch muscle (as discussed in lecture):Accept any of the following (2 pts. each for a total of 6 pts):- Use glycolysis (anaerobic) to produce ATP- Fatigue easily- Low blood supply- Few mitochondria- Provide quick, powerful contractionsDefine polyneuronal innervation in words. In what type of organism do we observe it? Draw a figure that clearly illustrates polyneuronal innervation (note: your drawing must be CLEAR to get credit!)2 pts. for definition:- The innervation of a single skeletal muscle fiber by more than one motor neuron2 pts. for organism type:- Occurs in invertebrates, specifically arthropods 2 pts. for CLEAR illustration (see below)A human subject is connected to a pulse transducer and produces a trace with a period of 0.6 seconds. Make a drawing of this trace (as it would appear in LabScribe), paying close attention to the time scale. Include at least 5 cycles in your drawing and label the axes. Next, determine the heart rate for the subject. Show ALL work and include units! Motor Neuron #1 Motor Neuron #21 pt. for CLEAR illustration (see above) with 5+ cycles, labeled axes2 pts. for correct time scale (correctly labeling time as per period) on x axis2 pts. for calculations, showing ALL worko 0.6 sec/cycle  1 / 0.6 = 1.67 cycles/sec (Hz)  (1.67 cycles/sec) * (60 sec/ min) 1 pt. for correct answer with units o 100 beats per minute (bpm)How are sensory stimuli transduced by the nervous system (i.e. what form does a stimulus take within the nervous system?). How do sensory neurons encode the intensity of stimulation? Finally, how would sensory neurons communicate a change in stimulus intensity (going from a low to high stimulus amplitude, for example)? 2 Pts. for each of the following (bulleted points) for a total of 6 pts.- Sensory systems/neurons/receptors transduce sensory stimuli into electrical impulses. - The strength (amplitude) of a stimulus is encoded through the frequency of action potentials fired. - The greater the stimulus intensity, the greater the frequency of action potentials fired.V 0.6 1.2 1.8 2.4 3.0 sec Time2 Pts. for each of the following (bulleted points) for a total of 6 pts.- The graph above illustrates five data points, including the first response and maximum response, however, the majority of the data points are taken at or beyond the maximum response. - More data points must be collected between the first response andmaximum response (between stimuli of 0  1.0 Volts, for example) to illustrate recruitment- Students need to return to the experiment, decrease the increments between stimuli. For example, test the muscle responseto stimuli at 0.2, 0.4, 0.6, 0.8 Volts and so forth)As part of the skeletal muscle laboratory, you were asked to make a graph illustrating skeletal muscle recruitment. What is wrong with the graph below? What would you suggest be done to better illustrate recruitment? Be Descriptive! Use values on the graph to support your answer. 0 1.0 1.5 2.0 2.5Stimulus AmplitudeResponse Amplitude4.03.02.01.00.0You place your hand on a hot stovetop and immediately withdraw your hand. This reflex occurs even before you perceive a burning sensation in your hand or experience pain. Describe the stimulus-response pathway that is occurring using terminology used in lab (ex: afferent/efferent). Begin with the stimulus and trace the signal through to the ultimate action, the withdraw of your hand. 1 pt. for each of the following for a total of 4 pts:- Stimulus = heat/stovetop- Afferent pathway = one or more sensory neurons- Efferent pathway = one or more motor neurons- Effector = skeletal muscle in arm 2 pts. for stating /inferring the brain is not involved in the reflex response. Something to the following effect:- In all reflex pathways, sensory and motor neurons synapse in the spinal cord- Information does not ascend to the brain before the motor response is initiatedAction potentials fired from a single