The nervous systemIB MYP Biology: Subtopic test

1. 1
   A chef accidentally touches a hot pan with her hand. She pulls her hand away before she feels any pain, and only a moment later does she notice the burn.

   (a)

   Which part of the chef's body is the effector in this reflex?

   [1 mark]

   • AThe temperature receptors in her skin
   • BThe muscle in her arm
   • CThe spinal cord
   • DThe sensory neurone

   (b)

   Which sequence shows the correct order of events in a reflex arc?

   [1 mark]

   • AStimulus, effector, motor neurone, coordinator, sensory neurone, receptor, response
   • BStimulus, sensory neurone, receptor, motor neurone, coordinator, effector, response
   • CReceptor, motor neurone, coordinator, sensory neurone, effector, stimulus, response
   • DStimulus, receptor, sensory neurone, coordinator, motor neurone, effector, response

   (c)

   Explain why the reflex pulls the chef's hand away faster than a decision made by her brain.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   At a food festival in Mumbai, judges assess a new snack. They look at its colour, smell it, taste it, feel its texture in the mouth and listen to how loudly it crunches.

   (a)

   Which sense organ detects chemicals in food that are dissolved in saliva?

   [1 mark]

   • AThe tongue
   • BThe eye
   • CThe skin
   • DThe ear

   (b)

   Which stimulus is detected by the receptors in the retina of the eye?

   [1 mark]

   • ASound
   • BChemicals in the air
   • CLight
   • DPressure

   (c)

   Suggest why food seems to have less flavour when you have a blocked nose.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A class investigates whether reaction time is different for the dominant hand and the non-dominant hand, using the ruler-drop test. One student holds a 30 cm ruler vertically above the open fingers of a partner and drops it without warning. The partner closes the fingers as fast as possible, and the distance the ruler fell is read from the top of the thumb. Each student does five drops with each hand. One student's distances for the dominant hand were 14, 12, 13, 25 and 13 cm. For the non-dominant hand they were 18, 20, 19, 17 and 21 cm.

   (a)

   Identify the independent variable, the dependent variable and one control variable in this investigation.

   [3 marks]

   (b)

   Identify the anomalous result in the data. Calculate the mean distance for each hand, leaving out any anomalous result, and state a conclusion.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Doctors test reflexes by tapping just below the knee with a small hammer, which makes the lower leg kick forward without the patient deciding to move it. Missing or unusual reflexes can show damage to the nerves or spinal cord. For some patients with spinal cord injuries, researchers are now trialling implants that stimulate nerves electrically to help them move paralysed muscles.

   (a)

   Explain how the knee-jerk reflex happens, from the tap of the hammer to the movement of the leg.

   [6 marks]

   (b)

   Discuss and evaluate the use of electrical nerve implants to help patients with spinal cord injuries. Give a justified conclusion.

   [6 marks]

   Total for question 4: 12 marks

End of questions