Question

The roundworm Caenorhabditis elegans is a widely studied animal model, in part because of its small number of neurons and easily manipulated genome. Nociception is the neural perception of an actually or potentially harmful stimulus. In C. elegans, it evokes a self-preserving withdrawal behavior. However, repeated stimulation can result in reduced withdrawal response, or habituation. Researchers compared the withdrawal response to disturbing light stimuli in wild-type C. elegans and a mutant C. elegans line that exhibits a slower response of sensory neurons (PVD) The given scatterplot shows the data of the percent of animals tested that exhibited a withdrawal reaction to a noxious stimulus consisting of varying numbers of consecutive light pulses. Failure to react indicates habituation Circles represent wild-type C. elegans, and squares represent the mutant line 100 80 o Wild type Mutant 20 5 10 15 20 Number of light pulses What does the scatterplot show about the difference between wild-type and mutant C. elegans lines? Explain why these results suggest an involvement of PVD sensory neurons in nocicep tion and habituation. Select the correct statement. Both the wild-type and the mutant C. elegans show a negative linear association indicative of habituation, but the habituation is stronger for the mutant. The difference in reaction to the number of light pulses suggests that PVD sensory neurons are not involved in nociception and habituation Both the wild-type and the mutant C. elegans show a positive linear association indicative of habituation, but the habituation is stronger for the mutant. The difference in reaction to the number of light pulses suggests that PVD sensory neurons are involved in nociception and habituation Both the wild-type and the mutant C. elegans show a negative linear association indicative of habituation, but the habituation is stronger for the mutant. The difference in reaction to the number of light pulses suggests that PVD sensory neurons are involved in nociception and habituation.

Answer 1

The scatterplot shows that there is a decreasing pattern for Wild type and Mutant. The decreasing pattern shows that there is a negative linear association indicative of habituation, but the slope is different for both Wild type and Mutant. If the same number of stimuli provided, the percentage of animals displays the withdrawal reaction is more for wild type compared to the withdrawal reaction for mutant. This indicates that the habituation is stronger for mutant. The difference in reaction to the number of light pulses states that PVD sensory neurons are involved in non-inception and habituation. The correct answer is option(c).