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Science · Drill 10

Science practice 10

15 questions ~9 min recommended
⏱ 00:00
Score
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I appreciate the detailed instructions, but I need to clarify an important issue with this request. The passage you've provided is **not a traditional ACT English passage**. It consists entirely of: - A diagram/schematic of lab equipment (Slits, Power supply, Agarose gel, Buffer solution) - Two data tables (one showing factor variations and effects, one showing agarose concentration vs. DNA size range) - A gel electrophoresis diagram (showing DNA fragment sizes from 10 kb to 0.5 kb) **This is a science passage (ACT Science section), not an English passage (ACT English section).** The questions reference specific data points, lanes, alleles, and scientific procedures—not grammar, punctuation, word choice, or sentence structure. **The ACT English section requires:** - Continuous prose text with clearly marked underlined portions - Questions about grammar, style, organization, and rhetoric - Standalone digits marking exactly where underlines end **This science material:** - Has no underlined text to mark - Has no prose narrative to format as HTML paragraphs - Cannot be formatted using the underline/subscript pattern you described **To proceed, I would need:** 1. Clarification that this is intentionally a Science passage (in which case HTML formatting isn't applicable), OR 2. An actual **English passage** with continuous prose text and marked underlined portions Could you provide an actual ACT English passage, or confirm you need a different format for this science material?

Agarose gel electrophoresis is a technique in which an electric field is used to separate fragments of DNA by size. Figure 3.2 illustrates a common setup of an electrophoresis apparatus. A square of agarose gel is prepared and placed in a tray of buffer solution. DNA in solution is loaded into small slits (wells) in the top of the gel. A solution of DNA fragments of known length, called a DNA ladder, is loaded in the first well. DNA samples to be studied are loaded in the remaining wells, and an electric current is applied to the apparatus. Since DNA is negatively charged, the DNA molecules in the wells travel toward the opposite, positive end of the gel. Smaller DNA fragments are able to move through the gel more easily and thus move faster than longer fragments. This causes the fragments to separate according to size as the procedure runs. Comparison to the DNA ladder provides an estimate of the separated fragments' sizes.

Figure 3.2

In addition to fragment size, several factors can affect the rate of migration of DNA fragments through the agarose gel. Table 3.4 provides a summary of the effects of agarose gel concentration and voltage of the electric current.

TABLE 3.4 Factors Affecting Fragment Migration

Table 3.5 identifies the agarose gel concentration needed for optimum resolution of DNA fragments within various size ranges.

TABLE 3.5 Agarose Concentrations

Source: http://www.idtdna.com/pages/decoded/decoded-articles/pipet-tips/decoded/2011/06/17/running-agarose-and-polyacrylamide-gels.

One application of the gel electrophoresis technique is to identify the alleles an individual carries for a particular gene. Although there may be multiple possible alleles (versions) for a specific gene, each individual carries exactly two copies. When subjected to electrophoresis, each allele separates out into a distinct band, allowing that individual's pair of alleles to be identified. A single darker band indicates two copies of the same allele.

Figure 3.3 shows electrophoresis results for a gene with three possible alleles. Allele 2 is known to contain extra bases as compared to Allele 1. Allele 3 is known to be missing bases as compared to Allele 1. DNA samples from 16 different individuals are loaded in Lanes A through P. The sizes of the known fragments in the DNA ladder are listed along the left.

Figure 3.3

1. In a standard gel electrophoresis procedure, the first well is generally reserved for:

2. Applying an electric current to the electrophoresis apparatus causes the DNA fragments to travel:

3. According to the passage, the role of a DNA ladder is to:

4. Which of the following would be a disadvantage of running a gel electrophoresis at a voltage of 6 V/cm?

5. According to Table 3.5, as the concentration of agarose increases, the range of DNA fragment sizes that can be resolved:

6. Which combination of factors would provide the best results for DNA fragments of 0.5-0.7 kb?

7. When observing electrophoresis results, the largest DNA fragments will appear:

8. Based on the information in the passage, Allele 2 traveled through the agarose gel faster than:

9. According to the passage, a single darker band, as seen in Lane E, most likely indicates an:

10. What is the approximate size of Allele 1?

11. What is the most common allele combination represented in the DNA samples shown in Figure 3.3?

12. Which of the following provides the best explanation for the result shown in Lane J?

13. Which allele combination is not represented in the DNA samples shown in Figure 3.3?

14. Which agarose concentration was most likely used in the electrophoresis in Figure 3.3?

15. Which combination of factors would cause the slowest migration of DNA fragments?

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