Victory for the ACT Student Text 15e

310 • S CIENCE

10. ……‘”†‹‰ –‘ ”‡Ž‹ƒ„Ž‡ •…‹‡–‹ϐ‹…”‡•‡ƒ”…Šǡ dry whole milk contains approximately 38% lactose by weight and liquid whole milk contains between 3.6% and 5.0% lactose by weight. Which of the following best explains why dry whole milk has a much higher lactose content than liquid whole milk? F. Removing water from whole milk greatly reduces the weight of the product while the amount of lactose remains the same. G. The process of removing water from whole milk to produce dry whole milk also removes an equal weight of lactose. H. When whole milk is processed into dry milk, the loss of liquid weight is balanced by the addition of an equal weight of lipids. J. Removing water from whole milk to produce dry milk concentrates the starch content in the dry milk left behind. PASSAGE III Erosion refers to processes that wear down rocks and soil, as well as processes that transport the worn-away materials to other locations. Although these processes usually cause effects gradually (over geologic time), laboratory models can be designed to investigate which environmental factors affect erosion rate. Three experimental sandboxes were set up that were identical in size (10-by-10- foot), had identical types of soil and rocks, ƒ† ™‡”‡ ϐ‹ŽŽ‡† –‘ ‡“—ƒŽ †‡’–Š• ȋ͵ ˆ‡‡–ȌǤ Š‡ sandboxes were kept for two weeks in large environmental chambers, each maintained at a constant temperature, with a continuous wind ϐŽ‘™ ‘ˆ ͷ ’ŠǤ Sandbox 1 One-half of Sandbox 1 was kept bare (just soil and rocks), while the other half had a variety of grasses and weeds planted among the soil and rocks. After two weeks, the bare half had small channels (ruts) running along

11. The students created an additional test substance by mixing whole milk with sucrose and then testing the mixture with Benedict’s solution following the procedures used in Experiment 1. The expected color of the liquid is: A. blue. B. green. C. yellow. D. red-brown.

RESEARCH SUMMARY STRATEGIES

its length that averaged 1 inch in width. The planted half had few channels, and those that were found averaged less than 1 inch wide. Sandbox 2 The conditions of Sandbox 2 were identical to those of Sandbox 1, with the addition that both halves were subjected to light, 15-minute showers of water every 12 hours. After two weeks, the bare half had channels averaging 4 inches wide, while the planted half had fewer channels, averaging 2 inches wide. Sandbox 3 The conditions of Sandbox 3 were identical to those of Sandbox 2, but the entire box was mechanically raised to rest at an angle of 15° to simulate a steep slope. After two weeks, the bare half had channels averaging 7 inches wide, while the planted half had fewer channels, averaging 4 inches wide.

The Cambridge Edge Use the following strategies for Research Summary passages: 1. Identify the controls and the variables. 2. Anticipate how to alter experimental variables to support alternative hypotheses and predict the results of these new experiments. 3. For depicted data trends, determine any proportional or inverse relationships. 4. Question the validity of any assumptions.