Practice Test 6
•25 QuestionsA biology teacher described an experiment in which students placed identical sprigs of aquatic plant into three sealed jars of pond water, each jar receiving the same mass of plant and the same volume of water. Jar 1 sat on a sunny windowsill; Jar 2 remained in a dark cabinet; Jar 3 stayed on the windowsill but was wrapped in a thin cloth that allowed warmth through while dimming the light. On the first afternoon, students noted small bubbles clinging to leaves in Jar 1, fewer bubbles in Jar 3, and none in Jar 2. By the next morning, Jar 2’s water appeared slightly cloudy, and the plant looked limp, while Jar 1’s water remained clear and the sprig looked firm. The teacher did not name the gas in the bubbles, but she asked students to record how quickly bubbles formed after the jars were gently shaken, and she reminded them that the lids were never opened. When a student suggested adding sugar “to feed the plant,” the teacher only asked whether the plant’s “food” was more like a solid, a gas, or a form of energy, then pointed to the cloth-wrapped jar and said, “Notice what changed and what did not.” At the end of the week, the class weighed the sprigs again; Jar 1’s sprig had gained a small amount of mass, Jar 3’s had changed little, and Jar 2’s had lost mass.
A biology teacher described an experiment in which students placed identical sprigs of aquatic plant into three sealed jars of pond water, each jar receiving the same mass of plant and the same volume of water. Jar 1 sat on a sunny windowsill; Jar 2 remained in a dark cabinet; Jar 3 stayed on the windowsill but was wrapped in a thin cloth that allowed warmth through while dimming the light. On the first afternoon, students noted small bubbles clinging to leaves in Jar 1, fewer bubbles in Jar 3, and none in Jar 2. By the next morning, Jar 2’s water appeared slightly cloudy, and the plant looked limp, while Jar 1’s water remained clear and the sprig looked firm. The teacher did not name the gas in the bubbles, but she asked students to record how quickly bubbles formed after the jars were gently shaken, and she reminded them that the lids were never opened. When a student suggested adding sugar “to feed the plant,” the teacher only asked whether the plant’s “food” was more like a solid, a gas, or a form of energy, then pointed to the cloth-wrapped jar and said, “Notice what changed and what did not.” At the end of the week, the class weighed the sprigs again; Jar 1’s sprig had gained a small amount of mass, Jar 3’s had changed little, and Jar 2’s had lost mass.