All practice questions

A researcher studying bacterial bioluminescence (*Vibrio fischeri*) sets up four separate culture tubes to evaluate light output under various conditions. Match each experimental setup (left) with its corresponding role or baseline condition in the study (right).

Match each trigonometric function on the left with its correct combination of amplitude and period on the right.

A geochemist designed an experiment to evaluate the adsorption capacity of engineered biochar for lead ($Pb^{2+}$) ions in contaminated synthetic groundwater. In a series of experimental trials, the researcher systematically set the solution pH to different specific levels ($4.0$, $6.0$, and $8.0$) to observe its direct effect on heavy metal removal. After a $24$-hour equilibrium period, the scientist measured the final concentration of adsorbed $Pb^{2+}$ ions remaining on the biochar surface. Throughout all trials, the initial $Pb^{2+}$ concentration ($50\text{ mg/L}$), mass of biochar ($0.50\text{ g}$), vessel volume ($100\text{ mL}$), ambient temperature ($25^\circ\text{C}$), and agitation speed ($150\text{ rpm}$) were held strictly constant.

Match each experimental component listed on the left with its correct variable classification on the right.

An acoustic engineer conducts an investigation to measure how changing the thickness of fiberglass insulation panels affects the sound intensity level (in decibels) transmitted through a drywall frame assembly. During all test runs, the sound source frequency is held constant at $1,000\text{ Hz}$, the room temperature is maintained at $22^\circ\text{C}$, and the dimensions of the drywall test frame remain identical. Match each experimental element from the study to its correct variable classification.

Researchers conducted an experiment to evaluate the inhibitory effect of copper sulfate (CuSO4) on the enzymatic activity of catalase, which breaks down hydrogen peroxide (H2O2) into water and oxygen. Four test tubes were prepared under identical temperature and pH conditions:

- Tube 1: 5.0 mL H2O2 solution + 1.0 mL distilled water (No catalase enzyme, no CuSO4)
- Tube 2: 5.0 mL H2O2 solution + 1.0 mL catalase solution (Catalase present, no CuSO4)
- Tube 3: 5.0 mL H2O2 solution + 1.0 mL catalase solution + 0.1 mM CuSO4
- Tube 4: 5.0 mL H2O2 solution + 1.0 mL catalase solution + 1.0 mM CuSO4

Match each experimental setup on the left with its intended baseline or experimental role on the right.

Oceanographers conducted an investigation to determine how variations in seawater salinity affect the vertical settling rates of marine micro-calcite ($CaCO_3$) particles. Synthetic seawater samples were prepared at four salinity levels ($30\ \text{PSU}$, $33\ \text{PSU}$, $35\ \text{PSU}$, and $38\ \text{PSU}$). In each trial, micro-calcite particles of uniform diameter ($50\ \mu\text{m}$) were dropped into a $1\text{-meter}$ vertical settling column maintained at a constant water temperature of $20^\circ\text{C}$. The elapsed transit time required for each particle to sink through the $1\text{-meter}$ distance was recorded to calculate its terminal sinking velocity.

Match each experimental component from the investigation to its correct variable classification.

A botanist conducted a 6-week experiment to evaluate the efficacy of three newly developed organic fertilizers ($F_1$, $F_2$, and $F_3$) on the growth rate of *Solanum lycopersicum* (tomato plants). All groups were maintained under controlled environmental conditions ($22^\circ\text{C}$, 16-hour light cycle). Match each experimental group setup to its corresponding functional role in the experiment.

A student constructs a respirometer apparatus to measure the rate of cellular respiration ($O_2$ consumption) in germinating seeds. Match each component of the apparatus to its primary experimental function in the setup.

A team of microbiologists investigated the impact of synthetic micro-plastic additives ($P_1$ and $P_2$) on the rate of nitrogen fixation by *Rhizobium* bacteria in soil culture vessels. Four identical culture vessels were prepared and incubated at $22^\circ\text{C}$ with $15\%$ baseline soil moisture for 14 days under the following conditions:

- Vessel 1: Standard nutrient medium + live *Rhizobium* bacteria (no plastic additives)
- Vessel 2: Standard nutrient medium + sterile (non-viable) *Rhizobium* bacteria + additive $P_1$
- Vessel 3: Standard nutrient medium + live *Rhizobium* bacteria + additive $P_1$
- Vessel 4: Standard nutrient medium + live *Rhizobium* bacteria + additive $P_2$

Match each experimental vessel on the left with its intended role in establishing control conditions or testing experimental variables on the right.

A team of atmospheric chemists investigated the photochemical formation of secondary organic aerosols (SOAs) in a $5\text{ m}^3$ Teflon smog chamber. Across four distinct experimental runs, researchers introduced constant initial concentrations of $\alpha$-pinene ($100\text{ ppb}$) and ozone ($200\text{ ppb}$) into the chamber alongside ammonium sulfate seed aerosols ($15\ \mu\text{g/m}^3$). Chamber temperature was maintained at $298\text{ K}$ and relative humidity at $50\%$. The ultraviolet (UV) light irradiance was set to a different value for each run ($0\text{ W/m}^2$, $25\text{ W/m}^2$, $50\text{ W/m}^2$, or $100\text{ W/m}^2$). After 4 hours of continuous irradiation, the researchers measured the final total SOA mass concentration ($\mu\text{g/m}^3$) produced in the chamber.

Match each experimental component to its correct variable classification.

An environmental science team investigated the effects of soil moisture on soil microbial respiration rates. In five experimental plots, they adjusted the soil volumetric water content to values ranging from $10\%$ to $50\%$. Throughout all trials, they kept the soil temperature constant at $22^\circ\text{C}$ and maintained a uniform soil bulk density. At the end of 48 hours, they measured the total carbon dioxide ($CO_2$) efflux from each plot.

Match each experimental component listed on the left with its correct variable classification on the right.

Biomechanical engineers investigated how the initial knee flexion angle affects the peak vertical ground reaction force generated by athletes during a countermovement jump on a stationary force plate. In the experiment, athletes performed jumps starting from pre-determined knee flexion angles (30°, 45°, 60°, and 75°), while force plate sensors continuously recorded the maximum force exerted against the platform during takeoff. All trials were conducted using the same athlete cohort wearing identical athletic footwear under standardized indoor temperature and humidity conditions. Based on this experimental design, match each experimental component to its corresponding variable classification.

A team of biogeochemists investigated anaerobic oxidation of methane by marine sediment microbes under simulated deep-sea temperature conditions ($4^\circ\text{C}$). Four distinct reactor setups were prepared containing equal masses of marine sediment and methane gas, but with varying additions of electron acceptors, heat sterilization, and hydrostatic pressures.

Match each experimental setup to its corresponding role or baseline function in the experiment.

A marine biologist conducted an experiment to evaluate how water flow velocity affects the peak bioluminescence intensity produced by the dinoflagellate *Pyrocystis fusiformis*. In four separate experimental trials, cell cultures were exposed to flow velocities of $0.1\text{ m/s}$, $0.5\text{ m/s}$, $1.0\text{ m/s}$, and $2.0\text{ m/s}$. In each trial, the cell density ($1{}000\text{ cells/mL}$), water temperature ($20^\circ\text{C}$), and ambient light intensity ($0\text{ lux}$) were kept constant.

Match each experimental variable category on the left with its corresponding component from the experiment on the right.

A team of atmospheric chemists investigated photochemical smog formation by measuring ozone ($O_3$) production in a sealed $10\text{ m}^3$ environmental chamber. Across five experimental trials, the researchers systematically varied the ultraviolet (UV) light irradiance level ($20$, $40$, $60$, $80$, and $100\text{ W/m}^2$). In all trials, chamber temperature ($25^\circ\text{C}$), relative humidity ($50\%$), and initial concentrations of nitrogen dioxide ($NO_2$, $0.5\text{ ppm}$) and volatile organic compounds ($VOCs$, $2.0\text{ ppm}$) were held constant. The rate of $O_3$ concentration accumulation was recorded over a 60-minute period.

Match each experimental component to its correct variable classification.

Engineers conducted an oceanographic experiment to test the efficacy of two nanocomposite surface coatings (Type-X and Type-Y) designed to prevent biofouling-induced galvanic corrosion on submerged sensor housings. Four identical titanium alloy test cylinders were placed in separate environmental chambers containing synthetic seawater for 30 days under the following conditions:

- Chamber 1: Uncoated titanium cylinder in sterile synthetic seawater (no biofouling organisms).
- Chamber 2: Uncoated titanium cylinder in synthetic seawater containing *Balanus amphitrite* larvae (biofouling organisms present).
- Chamber 3: Type-X coated titanium cylinder in synthetic seawater containing *Balanus amphitrite* larvae.
- Chamber 4: Type-Y coated titanium cylinder in synthetic seawater containing *Balanus amphitrite* larvae.

Match each experimental chamber to its corresponding role or purpose within the experimental design.

A team of materials scientists investigated the damping performance of magnetorheological (MR) fluids for automotive suspension systems. Identical $50\text{ mL}$ MR fluid samples at a constant temperature of $25^\circ\text{C}$ were exposed to four different magnetic field strengths ($0.1\text{ T}$, $0.3\text{ T}$, $0.5\text{ T}$, and $0.7\text{ T}$) while maintaining a constant rheometer shear rate of $100\text{ s}^{-1}$. The apparent yield stress of the fluid was measured for each trial.

Match each experimental factor on the left with its correct variable classification on the right.

A chemist measured the volume of carbon dioxide ($CO_2$) gas collected during a reaction at three different temperatures over a 10-minute period, recorded in the table below.

Match each reaction temperature condition with the curve characteristic that best describes its dataset when translated into a line graph of Volume vs. Time.

A team of aerosol scientists investigated the drying kinetics of levitated liquid microdroplets in an acoustic levitation chamber. In four separate trials, the relative humidity inside the chamber was adjusted to $10\%$, $30\%$, $50\%$, or $70\%$. In all trials, the acoustic transducer frequency was maintained at $40\text{ kHz}$, the ambient temperature was held constant at $22^\circ\text{C}$, and each droplet had an initial volume of $5.0\text{ }\mu\text{L}$. The researchers measured the rate of droplet volume reduction over time.

Match each experimental component on the left with its corresponding variable role on the right.

A plant physiologist conducted an experiment to investigate stomatal conductance in *Phaseolus vulgaris* (bean plant) leaves under various treatments of a synthetic phytohormone analog, Compound Y. Match each experimental group to its specific baseline or functional role within the experimental design.