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Paper 28

ACT December 2017

Form A10 · Science Test · 40 questions

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Paper 28 · ACT December 2017 · Form A10 · Science Test

3% aqueous mixture of which gum has the highest viscosity. wxyz wxyz gum mixture gum mixture

AGumwBGumxCGumyDGutn Z

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Paper 28 · ACT December 2017 · Form A10 · Science Test

Based on Table I, if a just-prepared 1.0% aqueous mixture of Gum Y is ajlowed to sit at rest for 100 min at 65°C, its viscosity will most likely be: ACT-A10 39 GO ON TO THE NEXT PAGE. 40000000004 Pa88age11 Study 2 The students prepared 7 different mixtures of BD and PD, each containing a different percent by volume of BD. Then, they measured A at 1,746 cm for a sample of each of the 7 mixtures, a sample of pure BD, and a sample of pure PD (see Figure 2). Biodiesel (BD) is a renewable alternative to tradi- tional petroleum diesel (PD). BD is typically prepared by reacting soybean oil with melbanol in the presence of a cat- alyst, forming Compounds called falty acid methyl e.Flers (FAMES). In contrasL PD contains no FAMES. The pres- ence of FAMES in BD causes BD to absorb infrared light differently than does PD. This difference allows pure BD, pure PD, and mixtures of BD and PD to be distinguished by analyzing the absorbance of infrared light. Students performed 3 studies in which they deter- mined the infrared absorbance characteristics of pure BD, pure PD, and mixtures of BD and PD. Study I The students measured the absorbance, A, of a sample of pur¢ BD and a sample of pure PD at wavenumbers from 600 cm through 1,800 cm The wavenumber corre- sponding to a given wavelength is defined as the wavelength ' where the wavelength is given in cm and the resulting wavenumber is given in cm They plotted the results for each sample (see Figure l). 20 40 60 80 100 percent BD by volume Figure 2 Figures 1 and 2 adapted from A. P. Ault and R. Pomery, "Quanlita- tive Investigations of Biodi8sel Fu81 Using Infrared Spectroscopy.. An Instrumental Analysis Experiment for Und8rgraduatÈ Chemistry Students." 2011 by Division of Chemical Educatlon, In¢,, Ameri- can Chemlcal Society. Key BD PD Study 3 The students obtained 4 different Siimples of commer- cial fuel blends of BD and PD (Samples W-Z). They mea- sured A at 1,746 cm for each sample, and then used Figure 2 to calculate the percent BD by volume of each sample (&*ee Table l). Table I Sample Percent BD by volume 600 800 1,000 1,2(K) 1,400 1,600 1,800 wavenumber (¢m ) Table 1 adapted Irom Z. V. Feng and J. T. Buchman, "Inslrumenlal Analysls of Biodie8el Cont8nt in Commerclal Diesel Blends: An Experlment for Undergraduate Analytical Chemistry." @2012 by Dtvision of Chemical Education, Inc., American Chemical Swiely. Figure I ACT-A10 40 GO ON TO THE NEXT PAGE. 40000000004

Aless than 500 CP.Bbetween 500 CP and 800 CP.Cbetween 8(X) CP and 1,100 CP.Dgreater than I, IOO CP. 0.15 0.10 0.05

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Paper 28 · ACT December 2017 · Form A10 · Science Test

Compound X is a chemical that caui>es genetic muta- tions in human cells. Suppose it were determined that human neurons grown in the presence of Compound X agc at the same rate as human neuron.s grown in the absence of Compound X. This finding would weaken the explanation(s) given by which of the .8tudents? animal cells increases the rate at which those cells age. animal cells increases the rate at which those cells age. cells increases the rate at which those cells age. Lells increases the rate at which those cells age. ACT-A10 45 GO ON TO THE NEXT PAGE. 4000000000 Passage V In a lake, water leaches (dissolves out) soluble organic compounds from decaying tree leaves, producing dissolved orgartic carbon (DOC). DOC is subsequently rcmoved from the water if it is adsorbed by (becomes adhered to the surface of) clay mineral particles that are suspended in the water. Three studies done at a lake exam- ined DOC adsorption by 3 clay minerals-cm I, CM2, and CM3-found in the lake's sediment. Study 2 Study I was repeated, substitutkng CM2 for CMI (see Figure 2). 60 50 40 30 20 10 Green leaves were collected from 5 types of trees around the lake (maple, oak, pine, magnolia, and rhodo- dendron). A 5 L volume of lake water was filtered to remove all solid particles. The following procedures were performed for each type of leaf: A 100 g sample of the leaves was mixed with a l L volume of the filtered lake water. The mixture was then placed in the dark for 10 weeks at 4°C while lea¢hing occurred. At 10 weeks, the mixture was filtered to remove all solid particles. The resulting liquid (the leachate) was analyzed for DOC. leachale Figure 2 Study I The following Procedures were performed for each leachate: A 100 ML volume of the leachate was mixed with 10 g of CMI. The mixture was stirred continuously for 2 hr, then filtered to remove all solid particles. The result- ing liquid (thefiltrate) was analyzed for DOC. The percent of the leachate DOC that had been adsorbed by CMI was calculated (see Figure l ). Siud.v 3 Study I was repeated, substituting CM3 for CMI (see Figure 3). 50 60 50 40 10 20 10 leachate Figure 3 leachate Flgures and table adapted Irom Todd Ti8tj8n, Ans81 vahatalo, and Robert Wetzel, °Effects of Clay Mineral Turbidity on Dissolved Organic Carbon and Bact8rial Production. 2005 by the Swiss Federal In81itut8 for Environmental Science and Technology. Figure I ACT.A10 46 GO ON TO THE NEXT PAGE. 40000000004

AStudent 2 onlyBStudent 3 onlyCStudents l and 3 onIyDStudents 2 and 4 onlyEIncreasing the number of protein cross-links in6Decreasing the number of protein cro88-liiiks in7Increasing the antioxidant concentration in animal8. Decreasing the antioxidant concentration in animal

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Paper 28 · ACT December 2017 · Form A10 · Science Test

What was the indcpcndent (manipulated) variable in each of the 3 studies and what was the independent variable across the 3 studies? in each study volume of leaf leachate volumc of filtratc across the studies type of clay mineral type of clay mineral mass of clay mineral mass of leaves ACT.A10 47 GO ON TO THE NEXT PAGE. 40000000004 Pa8sage Vl Plant roots can respond to a stimulus. Response to light Is phototropism; response to gravity is gravitropism. Growth toward a stimulus is a positive tropism; growth away from a stimulus is a negative tropism. For 2 experimenis with wild-type (WT) and mutant (M) Arabidopsis seeds, nutrient agar was put into each of 8 petri dishes (PDI-PD8). Experiment I Six WT Arabidopsis seeds were placed in each of PDI and PD2. Six M Arabidopsis seeds were placed in each of PD3 and PD4. Then, PDI and PD3 were placed in the dark for 70 hr, and PD2 and PD4 were exposed to light from above for 70 hr. Figure I shows the growth of the hypocolyls (seedling stems) above the surface of the nutri- ent agar and the growth of the radicles (s¢edling roots) below the surface of the nutrient agar in each disb at 70 hr. Then, PD5 and PD7 wer¢ exposed to light from above for 25 hr while PD6 and PD8 were exposed to light from below for 25 hr. At various times during the 25 hr, thc downward curvature, in degrees (.), of the radicle (Telative to its starting position) of each seedling in each dish was measured. The average downward curvature of the Tadicles in each dish at each measurement time is shown in Figure 3. Key -o- PD5 PD6 -D-- PD7 -•-- PD8 20 40 light from above light from below nutrient agar 100 0 5 10 15 20 25 0 5 10 15 20 25 time (hr) PDI PD2 Figure 3 Figures adapted from Stanislav Vltha, Liming Zhao. and Fr8d David Sack, °Interaction of Root Gravitroplsm and Phototropism in Arabidopsis Wild-Type and Starchless Mutants." 2000 by Ameri. can Society of Plant Physiologists. PD3 PD4

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Atyp¢ of lake wat¢rBtype of leaf leachateCChoice H — see source imageDChoice J — see source image

Form A10 · Science Test · 40 questions

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