Question

Response Questions Part A To B The roundworm Caenorhabditis elegans is a widelystudied animal model, in part because ofits small number of neurons and easilymanipulated 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. elegansand a mutant C. elegans line that exhibits a slower response of sen sory neurons (PVD). The given scatterplot shows the data of the percent ofanimals tested that exhibited a withdrawal reaction to a noxious stimulus consisting of varying numbers of consecutive light pulses. Failure to react in dcates habituation. Circles represent wild-type C. elegans, and squares represent the mutant line 100 80 60 40 e Wild type 20 10 15 20 Number of light pulses (a) What does the scatterplot show about the pattern of w ithdrawalresponses in wi-type C. elegans for increasing numbers of light pulses? stimulus is more pronounced when the stimulus is applied more times. more pronounced when the stimulus is applied more times. le ss pronounced when the stimulus is applied more times The negative linear associati on in the wild-type C. elegans does not indicate habi tuation: The response to the harmful The negative linear association in the wild-type C. elegans indicates habituation: The re sponse to the harmful stimulus is The negative linear associati on in the wild-type C. elegans indicates habituation: The re sponse to the harm ful stimulus is The negative linear associati on in the wild-type C. elegans does not indicate habituation: The response to the harmful stimulus is less pronounced when the stimulus is applied more times. (b) What does the scatterplot show about the difference between wild-type and mutant C elegans lines? Expain why these results suggest an invoy ement of PVD sensory neurons in nociception and habituation. Both the wild-type and the mutant C. elegans show a negative linear asso ciation in dicative of habiation, but the habituation is stronger for the mutant. The di are not involved in e in reaction to the number of light pulses suggests that PVD sensoryneurons nociception and habituation. Both the wild-type and the mutant C. elegans show a positive linear association indicative ofhabituation, but the habituation is stronger for the mutant. The difference in reaction to the number of light pulses suggests that PVD sensoryneurons 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 waker for the mutant. The difference in reaction to the number of light pulses suggests that PVD sensory neurons d 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 sensoryneurons d in nociception and habituation.

Answer 1

The experiment consists of studying the effect of stimulus on the withdrawal behavior of wild-type C anda mutant. Repeated stimulation can result in reduced withdrawal response or habituation. Hence, in the process of habituation the withdrawal is reduced as the stimuli is increased A scatterplot is drawn for the number of animals reacting against the number of light pulses. (a) The scatterplot indicates a decreasing pattern for both Wild type and Mutant. The decreasing pattern of the scatterplot indicates that with an increase in the stimuli the animal withdrawal reaction is decreased, that is, with an increase in the stimuli the habituation is increased. Therefore, the negative linear association in wild type-C elegans indicates habituation. The response to the harmful stimulus is less pronounced when the stimulus is applied more times. Thus, the third option is correct. (Ъ) The slope for the scatterplot of Wild Type and Mutant is different. For same number of stimuli provided, the percent of animals displaying a withdrawal reaction is more for Wild type as compared to Mutant. This implies that habituation is stronger for mutant. The difference in reaction to the number of light pulses suggests that PVD sensory neurons are involved in non-inception and habituation. Therefore, the fourth option is correct.