Question

independent versus dependent variable worksheet.
an independent variable is the one thing you intend to vary in an experiment.
a dependent variable is the thing that will change that you intend to measure as a quantitative assessment of the effect.
in the following examples identify the independent and dependent variables and then also list several potential confounding variables that the experimenters would have to consider.
sample hypotheses

1. if skin cancer is related to ultraviolet light, then people with a high exposure to uv light will have a higher frequency of skin cancer. what will you do to test this proposal? what will you vary or change? what will you measure?

independent variable --
dependent variable -

1. if leaf color change is related to temperature, then exposing plants to low temperatures will result in changes in leaf color.

independent variable --
dependent variable -

1. if the speed of plant germination is related to the hardness of the hull of its seed, then softening the seed with water or a weakly acidic solution prior to planting will hasten germination. blah, blah, blah…

independent variable --
dependent variable -

1. if photosynthesis is related to light energy, then the portions of a leaf shaded from light will test negative for starch, since starch is a product of photosynthesis.

independent variable --
dependent variable -

1. if animal metabolism is related to temperature, then increasing resting room temperature will increase animal metabolism (as measured by carbon dioxide gas production which is one of the waste products of animal metabolism).

independent variable --
dependent variable -

1. if root growth is related to gravity, then roots will always turn toward the earth regardless of a seed’s orientation.

independent variable --
dependent variable -

1. if hatching of brine shrimp is related to salinity (or temperature), then the greater the salt concentration, the higher the hatching rate.

independent variable --
dependent variable -

1. if the thickness of annual growth rings in trees is related to annual rainfall, then examining wood samples will reveal correlations in the growth rings to the historical records for rainfall in its environment.

independent variable --
dependent variable -

1. if poking a skunk will always result in the emission of noxious and toxic fumes.

independent variable --
dependent variable -

Explanation:

Independent variables are intentionally varied; dependent variables are measured outcomes. Confounding variables are extraneous factors affecting results.

Answer:

1. Independent variable: UV light exposure

Dependent variable: Frequency of skin cancer
Confounding variables: Sunscreen use, skin type, age

1. Independent variable: Temperature

Dependent variable: Leaf color change
Confounding variables: Light exposure, plant species, water availability

1. Independent variable: Seed hull hardness (softening method)

Dependent variable: Speed of plant germination
Confounding variables: Soil moisture, temperature, seed age

1. Independent variable: Light energy (shading)

Dependent variable: Starch presence in leaf portions
Confounding variables: Leaf health, CO₂ levels, time of day

1. Independent variable: Room temperature

Dependent variable: Animal metabolism (CO₂ production)
Confounding variables: Animal species, diet, activity level

1. Independent variable: Gravity (seed orientation)

Dependent variable: Root direction
Confounding variables: Soil texture, water location, seed type

1. Independent variable: Salinity (salt concentration)

Dependent variable: Brine shrimp hatching rate
Confounding variables: Temperature, water pH, shrimp egg quality

1. Independent variable: Annual rainfall

Dependent variable: Thickness of tree growth rings
Confounding variables: Temperature, soil nutrients, tree species

1. Independent variable: Poking a skunk

Dependent variable: Emission of noxious fumes
Confounding variables: Skunk stress level, time of day, presence of threats