# Lesson Worksheet: Reflex Actions Biology

In this worksheet, we will practice describing the structure of the reflex arc and explaining the advantages of having reflex actions.

Q1:

You are planning an investigation to measure reflex-reaction times. The method is outlined below:

1. Hold a ruler above your partner’s hand.
2. Drop the ruler.
3. Measure at what distance (in centimeters) your partner caught the ruler.
4. Repeat at different times of the day.

In this investigation, what is the independent variable?

• AThe ruler
• BThe person
• CThe distance the ruler is dropped from
• DThe distance the ruler is caught at (in centimeters)
• ETime of day

In this investigation, what is the dependent variable?

• AThe ruler
• BThe distance the ruler is dropped from
• CTime of day
• DThe person
• EThe distance the ruler is caught at (in centimeters)

Which of the following describes a way to make this study more accurate?

• AChanging the person dropping the ruler each time
• BRepeating the study three times and calculating the average reaction time for each time of day
• CChanging the person catching the ruler each time
• DUsing a different ruler every time so reaction time with different rulers can be measured
• ERepeating the study three times and determining the median reaction time

Q2:

You are in a building when someone shouts, “fire!” Without thinking, you start running.

In this reflex action, what is the stimulus?

• AThe fire
• BThe shout of “fire”
• CPeople running
• DThe muscles in your legs

In this reflex action, what is the effector?

• AShouting
• BSound receptors in your ears
• CThe muscles in your leg
• DRunning

Q3:

A bright light is pointed into your eye. Your pupil contracts to restrict the light entering.

In this reflex action, what is the effector?

• AThe eye
• BThe light
• CThe muscles around the pupil

In this reflex action, what is the response?

• AThe muscles around the pupil
• BLight receptors in eyes
• CThe pupil contracting

Q4:

You spot a football flying towards your face in a park. Without thinking, you duck.

In this reflex action, what is the response?

• BThe football
• CRunning
• DThe muscles in your body

In this reflex action, what is the receptor?

• ALight receptors in the eyes
• BPressure receptors in the skin
• CSound receptors in the ears
• DSound receptors in the skin

Q5:

Which of the following shows the correct process of a reflex arc?

• AStimulus, receptor, motor neuron, relay neuron, sensory neuron, effector, response
• BStimulus, receptor, sensory neuron, relay neuron, motor neuron, effector, response
• CReceptor, stimulus, sensory neuron, relay neuron, motor neuron, effector, response
• DReceptor, stimulus, relay neuron, sensory neuron, motor neuron, effector, response
• EStimulus, receptor, sensory neuron, relay neuron, motor neuron, response, effector

Q6:

For the following situations, choose the receptor that would most likely detect each stimulus.

A loud crash makes you jump.

• ASound receptors in the ears
• BPain receptors in the skin
• CLight receptors in the eyes
• DSound receptors in the skin
• ELight receptors in the brain

You hold your hand over a kettle and feel that it is warm.

• APain receptors in the muscle
• BPressure receptors in the skin
• CHeat receptors in the muscle
• DHeat receptors in the skin
• EPain receptors in the skin

You feel a sharp pinch in your arm as you are having an injection.

• APain receptors in the muscle
• BPressure receptors in the muscle
• CPain receptors in the skin
• DHeat receptors in the skin
• EPressure receptors in the skin

You see a bright light flash in the distance.

• APressure receptors in the eyes
• BLight receptors in the eyes
• CHeat receptors in the skin
• DSound receptors in the ears

Q7:

Why is it beneficial that reflex actions do not require thinking?

• ASignals are not passed to the brain, allowing the body to respond more quickly.
• BSignals bypass the entire central nervous system, so reactions are very slow.
• CSignals are not passed to the brain, allowing the body to respond slowly.
• DSignals are passed to the brain, allowing the body to respond more quickly.
• ESignals bypass the entire central nervous system, so reactions are very quick.

Q8:

Which of the following is not an advantage of having reflex actions?

• AReflex actions prevent a person from feeling pain.
• BReflex actions take care of basic bodily functions like breathing and heart rate.
• CReflex actions are involuntary.
• DReflex actions do not require the brain to think about responses before acting.
• EReflex actions allow a quick response to danger.

Q9:

You reach over an oven and accidentally touch a hot baking tray. You immediately pull your arm away.

In this reflex action, what is the stimulus?

• AThe hot baking tray
• BThe muscles in your arm
• CThe oven
• DThe movement of your arm

In this reflex action, what is the receptor?

• APain receptors in the brain
• BPressure receptors in the skin
• CPressure receptors in the brain
• DPain receptors in the skin

In this reflex action, what is the effector?

• AThe muscles in your arm
• BThe hot baking tray
• DThe movement of your arm

In this reflex action, what is the response?

• AThe hot baking tray
• BThe movement of your arm
• CThe movement of your legs
• DThe muscles in your arm

Q10:

Which of the following best describes the role of receptors in the human body?

• AThey bring about a response.
• BThey transmit signals across the central nervous system.
• CThey detect changes in the external environment.
• DThey transmit electrical impulses across synapses.
• EThey release hormones.

This lesson includes 28 additional questions for subscribers.