=== Compounds and C. elegans ===
Based on the results of Experiment 1, the C. elegans were most attracted to which of Compounds X, Y, or Z, if any? On Dish3 in Experiment1, the number of C.elegans that moved toward Compound Z was approximately how many times as great as the number of C.elegans that moved toward Compound Y? The single-dish experimental design shown in which of the following figures would have best allowed the students to determine which compound (X, Y, or Z) was most attractive to the C.elegans? In Experiments 1 and 2 combined, Compound Z was placed on a total of how many dishes? Based on the description of C.elegans in the passage, a cell from a C.elegans lacks which of the following structures? In Experiment 2, as the amount of pre-exposure time increased, did the number of C. elegans that were attracted to Compound Z increase or decrease?
=== Pythons and Metabolic Rate ===
In the python (Python molurus), a species of snake, organ mass and metabolic rate may decrease between meals, conserving energy. Figure 1 shows, for a group of juvenile pythons (GroupV), the average mass of the small intestine before and after each python ingested a single meal that had a mass equal to 25% of the python’s body mass. Figure 2 shows, for 4 groups of juvenile pythons (Groups W−Z), the average oxygen consumption rate, in milliliters of oxygen consumed per gram of body mass per hour (mL/g/hr), before and after each python ingested a single meal. Table 1 shows the relative mass of the meal ingested by the pythons in each group.
=== Solubility of Substances ===
The solubility of a substance is typically defined as the maximum mass, in grams (g), of the substance (the solute) that will stay dissolved in 100g of a solvent (such as water). The solubility of a substance generally varies as the temperature of the solvent changes. Figure1 shows, for each of 5 substances, how solubility in water varies with temperature.
=== Karymsky Lake ===
Karymsky Lake is located within a volcanic caldera. In April 1993, water samples were collected from the lake and analyzed for pH, for Na+, and for SO4. On January 2, 1996, a 2-day-long underwater eruption occurred in the lake. The eruption produced a crater on the bottom of the lake at the north end. In April 1996, water samples were again collected from the lake and analyzed for pH, for Na+, and for SO4.
=== ... ===
Twenty-five mL of methanol (a solvent) was added to the flask, and the mouth of the flask was covered with aluminum foil. The contents of the flask were boiled until a color change was observed (which signaled that the I2 had been completely consumed). The flask was allowed to cool, and the contents of the flask were filtered using filter paper. The filter paper was dried, and the mass of unreacted Zn on the filter paper was determined. The filtrate (the liquid that passed through the filter) was poured into a beaker and heated to evaporate the methanol, leaving a dry solid in the beaker. The mass of the dry solid was measured. The percent by mass of Zn and of I in the dry solid was calculated.