"use strict"; ({ prompt: "Suppose the researchers want to build an irritant _dose-response curve_, in order to determine the concentration of the irritant that produces the greatest mitotic index. Which variables should be graphed in the y and x-axes, respectively?", explanation: "For an irritant dose-response curve, the response is the Mitotic index, which should be graphed in the y-axis, while the stimulus is the concentration of irritant, which should be graphed in the x-axis.", itemType: "passageChooseOne", options: null, passage: "One of the most important functions of the cell is cell division. In this process, new cells are formed. All cells except for sexual cells carry out cell division by a process called _mitosis_, in which one parent cell produces two identical daughter cells.\n\nA group of scientists was studying cell division in the epidermis. The _epidermis_ is the outermost tissue of the body, and it is a barrier of entry for dangerous microorganisms. Studying cell division is important to assess the ability of the epidermis to self-heal and regenerate.\n\nScientists were studying the effect of some irritants on the mitotic response in the epidermis. The studied irritants were: dimethylacetamide (DMAC), 5% hydrochloric acid (HCl), 1% benzalkonium chloride (BACl), and 1% aqueous sodium lauryl sulfate (SLS). After applying these irritants to the skin of adult human males for a given period of time, the mitotic index (mitoses per thousand viable cells) was obtained. The results are shown in Table 1. An untreated control at time 0 h had a mitotic index of 0.94 ± 0.16.\n\n

Table adapted from Fisher, Louis B., and Howard I. Maibach. \"Effect of some irritants on human epidermal mitosis.\" _Contact Dermatitis_ 1.5 (1975): 273-276.
Table 1
Irritant	Mitotic index after time T
T = 24h	T = 48h	T = 96h
DMAC	0.13 ± 0.05	2.47 ± 0.61	0.89 ± 0.14
5% HCl	1.21 ± 0.16	1.35 ± 0.29	1.14 ± 0.24
1% BaCl	2.42 ± 0.32	1.59 ± 0.30	1.23 ± 0.16
1% SLS	2.51 ± 0.54	15.46 ± 3.70	9.33 ± 1.59

", answer: "Mitotic index vs. Irritant concentration", distractors: ["Irritant concentration vs. Mitotic index", "Mitotic index vs. Time", "Time vs. Mitotic index"] });

Loading...