Reflex Arc

Q.

What are the components of a reflex arc?

Q.

Which of the following is not involved in knee-jerk reflex?

(a) Muscle spindle (b) Motor neuron (c) Brain (d) inter neurons

Q.

Define reflex arc and its component.

Q.

Which of the following is an unconditioned reflex action?

1. Knee jerk

2. Playing musical instrument

3. Knitting without looking

4. Reading as well as writing

Q.

What are neurotransmitters? Give an example.

Q. Which of the following is not a part of the reflex arc during a reflex action?

1. Afferent neuron
2. Efferent neuron
3. Brain
4. Spinal cord

Q.

Give a reason for the following:

We quickly remove our hand when our finger gets accidentally pricked by a pin.

Q.

Which of the following statements is/are incorrect about the electrical synapse ?
a. At electrical synapses, the membranes of pre and post synaptic neurons are in very close proximity.
b. Electrical current can flow directly from one neuron into the other across the synapses
c.Transmission of an impulse across electrical synapses is very similar to impulse conduction along single axon
d. Electrical synapses are fast
e. Electrical synapse are more in our system.

1. b and d only

2. e only

3. a and c only

4. c only

Q. What is an example of conditioned reflex?

1. Your took up a stone and the dog runs away
2. You move your hand away when somebody pierces you with a needle
3. Eyes closed when anything enters into it
4. Movement of digestive food in the alimentary canal

Q. In the knee jerk reflex, the effector and receptor are respectively,

1. muscle spindle and motor endplate
2. afferent and efferent neuron
3. motor endplate and muscle spindle
4. sensory and motor neuron

Q. Complete the statement by choosing appropriate match among the following

Column I	Column II
(a)Resting potential	i. chemicals involved in the transmission of impulses at synapses.
(b)Nerve impulse	ii. gap between the pre synaptic and post synaptic neurons
(c)Synaptic cleft	iii.electrical potential difference across the resting neural membrane
(d)Neurotransmitters	iv.an electrical wave like response of a neuron to a stimulation.

Q.

Which of the following is an unconditioned reflex action?

1. Knee jerk

2. Playing musical instrument

3. Reading as well as writing

4. Knitting without looking

Q.

Reflex arc is the

1. response to external stimuli

2. instantaneous response without thought

3. pathway of impulses to and from spinal cord

4. pathway of the impulse to sense organs

Q. Describe reflex action and reflex arc.

Q. What is a reflex arc? Draw a neat labelled diagram of the components in a reflex arc. Why do impulses flow only in one direction in a reflex arc?

Q.

In a synapse, chemical signals are transmitted from

1. dendritic end of a neuron to the axonal end of another neuron.

2. axon to the cell body of the same neuron.

3. cell body to the axonal end of the same neuron.

4. axonal end of one neuron to the dendritic end of another neuron.

Q. Collateral fibres are given out along its way is–

1. Muscle fibre
2. Axon
3. Dendron
4. Dendrites

Q. The diagram given below shows the internal structure of a spinal cord depicting a phenomenon. Study the diagram and answer the questions.

(iii) Name the parts numbered 1, 2 and 3.

Q.

A reflex arc in man is best described as the movement of stimuli from

1. receptor cell, sensory neuron, relaying neuron, effectors muscles

2. receptor cell, efferent nerve, relaying neuron, muscles of the body

3. receptor cell, spinal cord, motor neuron, relaying neuron

4. receptor cell, synapse, motor neuron, relaying neuron

Q.

What are the parts of a typical reflex arc?

Q.

Why does Knee-jerk when you hit it?

Q. If we happen to touch a hot object unknowingly, we immediately pull back our hand.
What is the type of action known as?

Q.

Name the following:
Cells or neurons which are capable of perceiving stimuli.

Q. Draw a labelled diagram of reflex arc and explain reflex action.

Q. The following is the scheme showing the path of the reflex arc. Identify the different labelings A, B, C, D, E and F in the reflex arc

1. A - Stimulus, B - Effector, C - Motor nerve, D - Sensory nerve, E - Receptor, F - Response
2. A - Stimulus, B - Receptor, C - Motor nerve, D - Sensory nerve, E - Effector, F - Response
3. A - Stimulus, B - Effector, C - Sensory nerve, D - Motor nerve , E - Receptor, F - Response
4. A - Stimulus, B - Receptor, C - Sensory nerve, D - Motor nerve , E - Effector, F - Response

Q. Identify the statements as true/false. (xiv) Swallowing of food is an example of conditioned reflex

Q. Which of the following statements is an example of conditioned reflex?

1. Hand moving away when pierced with a needle
2. A trained dog salivating for food after the blow of whistle
3. In digestion food goes forward in the alimentary canal
4. Eyes closing when something enters into it.

Q. (a) What is a reflex action? Explain with the help of an example.

Q. Categorise the following under the headings, stimulus and response.
(iii) Withdrawal of hand on touching a hot plate.

Q.

A reflex arc in man is best described as movement of stimuli from:

1. Receptor cell, sensory neuron, relaying neuron, effector muscles.

2. Receptor cell, efferent nerve, relaying neuron, muscles of the body.

3. Receptor cell, spinal cord, motor neuron, relaying neuron.

4. Receptor cell, synapse, motor neuron, relaying neuron.