Photo AI
Eyestalk retraction in a crab is under the control of a sensory-motor reflex as shown in the diagram below - VCE - SSCE Biology - Question 16 - 2010 - Paper 1
Question 16
Eyestalk retraction in a crab is under the control of a sensory-motor reflex as shown in the diagram below. Note that the sensory and inhibitory neurones both form ... show full transcript
Worked Solution & Example Answer:Eyestalk retraction in a crab is under the control of a sensory-motor reflex as shown in the diagram below - VCE - SSCE Biology - Question 16 - 2010 - Paper 1
Step 1
A. retraction of the eyestalk if the sensory hair is stimulated.
Answer
If the sensory hair is stimulated, it will initiate the sensory-motor reflex pathway. This leads to the activation of the motor neurone, causing contraction of the retractor muscle and resulting in the retraction of the eyestalk. Therefore, this statement is true.
Step 2
B. retraction of the eyestalk if the inhibitory neurone is stimulated after cutting the sensory neurones at site J.
Answer
Cutting the sensory neurones at site J would prevent any sensory input from being integrated by the motor neurone. Even if the inhibitory neurone is stimulated, there is no sensory signal to process. Thus, this statement is false as retraction will not occur.
Step 3
C. no retraction of the eyestalk if the sensory and inhibitory neurones are stimulated after cutting the inhibitory nerve at site K.
Answer
If the inhibitory neurone is cut, its effect on the motor neurone will no longer be present, meaning there would be nothing preventing the retraction signal. Therefore, if sensory inputs are applied, there would be retraction, contradicting the statement. Thus, this option is also false.
Step 4
D. retraction of the eyestalk if the sensory and inhibitory neurones are stimulated at the same time at locations S and T respectively.
Answer
When both neurones are stimulated simultaneously, their effects will depend on their interplay. Typically, the co-activation of both may lead to a canceling effect depending on their dynamic with the motor neurone. However, retraction may still occur if the sensory input is dominant. This statement could potentially be true under certain conditions.