Identify the dependent and independent variables. Suggest possible controlled variables.?

Question

a) The height of bean plants is recorded daily for two weeks.

Dependent variable(s)___________

Independent variable____________

Controlled variables_____________

b) Guinea pigs are kept at different temperatures for six weeks. Percent weight gain is recorded.

Dependent variable(s)___________

Independent variable____________

Controlled variables_____________

c) Geranimums are given different types of fertilizers, and the number of seeds produced by each plant is counted.

Dependent variable(s)___________

Independent variable____________

Controlled variables_____________

d)Batches of seeds are soaked in different concentrations of salt solutions and number of seeds germinated is counted for each batch.

Dependent variable(s)___________

Independent variable____________

Controlled variables_____________

Answer 1

The above poster has his/her variables mixed up. The dependent variable changes as a result of you (or something else) changing the independent variable. For example, plants change height as a result of time, time doesn't change as a result of plants getting taller. Controlled variables are those that can affect the outcome so you keep them the same across all samples.

a) Dependent variable: height

Independent: time

Controlled: amount of water, food given, etc.

b) Dependent: weight

Independent: temperature

Controlled: food fed, exercise, etc.

c) Dependent: seeds produced

Independent: fertilizer type

Controlled: soil composition, water, sunlight

d) Dependent: number of seeds

Independent: salt concentration

Controlled: sunlight, soil type, etc.

Answer 2

Just remember here that the dependent variable is the one you're changing or time.  The independent variable is the one that you're measuring to see "what happened".  The controlled variables are everything else that might effect the final outcome if they varied between the members being tested.

a) The height of bean plants is recorded daily for two weeks.

Dependent variable(s) - time (# of days from start)

Independent variable - bean height

Controlled variables - light, water, fertilizer, temperature, soil type, pot size

b) Guinea pigs are kept at different temperatures for six weeks. Percent weight gain is recorded.

Dependent variable(s) - temperature

Independent variable - weight gain

Controlled variables - animal gender and age, food, water, cage size, amount of exercize allowed

c) Geranimums are given different types of fertilizers, and the number of seeds produced by each plant is counted.

Dependent variable(s) - fertilizer type

Independent variable - # of seeds

Controlled variables - light, amount of fertilizer, water, soil type, pot size

d)Batches of seeds are soaked in different concentrations of salt solutions and number of seeds germinated is counted for each batch.

Dependent variable(s) - salt concentration

Independent variable - # of germinated seeds

Controlled variables - light, plant species (should all be the same type of seeds for comparison), light, temperature

This is by no means the only "set" of answers - there are lots of other items, especially in the "controlled variables" that could be considered.