Scientific Method and Process

Trends:  An interpretation of data to decide if there is a relationship.

EX: Which of the following statements about the effect of mulch age on the consumption of mulch by R.flavipes is consistent with the figure? As mulch age increased from 1 week through 48 weeks, the mass of mulch consumed by R.flavipes:

• A. decreased for all 5 types of mulch
• B. increased for all 5 types of mulch
  
• C. initially decreased for all 5 types of mulch, but then increased for some of the 5 types of mulch.
  
• D.initially increased for all 5 types of mulch, but then decreased for some of the 5 types of mulch.
  

Direct correlation: occurs when two variables change in the same way over time.

EX: According to Figure 1, as the nickel concentration in the nutrient solutions increased, the average zinc content of Species M plants:

• F. increased only.
• G. decreased only.
• H. increased, then decreased.
• J. decreased, then increased.

Indirect (inverse) correlation: When two variables change in inverse proportion.

When Column A (Atomic #) increases, Column B (Abundance %) decreases.

EX: According to Study 3, as distance from the urban site increased, the annual wet deposition:

Study 3: The annual wet deposition of Cu²⁺ and of Zn²⁺ for the 12-month period, in µg/m², was calculated for the urban site (the source of the Cu²⁺ and Zn²⁺) and also for Rural Sites 1 and 2, located 50 km and 100 km east, respectively, of the urban site

• A. increased for both Cu²⁺ and Zn²⁺
• G. increased for Cu²⁺ but decreased for Zn²⁺
  
• H. decreased for both Cu²⁺ and Zn²⁺
• J. remained the same for both Cu²⁺ and Zn²⁺
  

No Direct or Inverse relationship: variables that are neither inversely nor directly related.

EX: Based on Table 1 and Figure 2, as the soil percent soil percentage decreased from 100% to 0%, the average plant yield:

• A. increased only.
  B. decreased only.
  C. increased, then decreased.
  D. decreased, then increased.

Extrapolation: an estimation to predict values for points outside the range of data points taken.

Interpolation: an estimation to predict values that fall within the range of data points taken.

EX: According to Figure , at 1 atm, a temperature of 130°C would most likely yield an absolute pressure:

• A. Less than 80 kN/ m²
• B. Between 80 and 100 kN/ m²
• C. Between 100 and 120 kN/m²
• D. Greater than 120 kN/m²

EX: Based on Table 1, a cosmic ray flux of 440,000 particles/m²/hr. would correspond to a cover of low clouds that is closest to which of the following?

• F. 28.7%
• G. 29.0%
• H. 29.3%
• J. 29.6%

EX: According to Figure , at 1 atm, a temperature of  65°C would most likely yield an absolute pressure:   

• F. Less than 20 kN/ m²
• G. Between 10 and 20 kN/ m²
• H. Between 20 and 40 kN/ m²
• J. Greater than 60 kN/m²

EX: If a trial had been performed in Experiment 2 at 425°C and 225 atm, the amount of NH₃ produced would most likely have been:

• A. less than 230 kg.
  B. between 230 kg and 320 kg.
  C. between 320 kg and 410 kg.
  D. greater than 410 kg

Data bridge: A skill that links multiple figures or tables.

EX: Based on the results of Experiments 1 and 2, which of the following is a possible transition range for curcumin?

• 
  F. pH = 3.9 to pH = 7.3
  G. pH = 4.2 to pH = 6.6
  H. pH = 7.4 to pH = 8.6
  J. pH = 8.4 to pH = 9.5

Variables: any factor that can be controlled, changed, or measured in an experiment.

Independent variables: are factors that a scientist Changed “Controlled” in an experiment.

Example: Did the scientists increase the heat in the experiment? Did they add or remove pressure?

EX: Based on samples 7-9, which element represents the independent variable?

• F. Sun
• G. Soil
• H. Water (mL)
• J. Height (cm)

Dependent variables: are factors that a scientist observe and measure in an experiment.

EX: Based on samples 1-3, which element represents the dependent variable?

• A. Sun
• B. Soil
• C. Water (mL)
• D. Height (cm)

Constant: parts of the experiment that the scientists keep the same.

EX: Based on Samples 4-6, which element(s) represent constants?

• F. Sun only
• G. Soil only
• H. Sun and Water
• J. Sun and Height

Control “Constant” variable: a variable that does not change during an experiment.

Examples of control variables include:

If a temperature is held constant during an experiment, it is controlled.

EX: Amount of light, using the same type of glassware, constant humidity, or duration of an experiment.

• EX: Which dish in the study was intended to serve the purpose of testing whether some of the S. typhimurium cells became His⁺ revertants without the addition of a mutagen?
• F. Dish 1
  G. Dish 2
  H. Dish 3
  J. Dish 4

Controlled experiments: an experiment in which all factors are held constant except for one: the independent variable.

Control group: The independent variable is “controlled” or held constant in an experiment.

Experimental group:  The independent variable is changed in an experiment.

EX: In this experiment, a student set up two identical pots. Both contain ten bean seeds planted in the same type of soil, and both are placed in the same window. except the following:

Hypothesis:  a part of the scientific method. It is a prediction or explanation that is tested by an experiment.

Inference: An educated guess made through an observation.

Example: The researchers conducting the studies chose to use a box made of a type of plastic rather than of wood to ensure that all of the water from the melting ice would flow from the box and into the trough. The researchers most likely made that choice because that type of plastic, unlike wood, is:

• F. porous and permeable, and therefore incapable of absorbing water.
• G. nonporous and impermeable, and therefore incapable of absorbing water.
• H. porous and permeable, and therefore capable of absorbing water.
• J. nonporous and impermeable, and therefore capable of absorbing water.