Question

dr. vet is developing new puppy–food formulas. she performs an experiment to see which of her three formulas causes the greatest increase in mass. she feeds a different formula to each of the three puppies. each puppy receives the same amount of food. each puppy’s mass in grams at the end of each week is recorded. in this situation,
a. what constant variables would you need in the experiment? name at least three.
b. what is the dependent variable?
c. what is the independent variable in this experiment?

Explanation:

Part a

Step1: Recall constant variables

Constant variables are factors kept the same in an experiment. Here, to ensure a fair test, factors like the amount of food each puppy gets, the puppies' initial mass (if controlled), and the time period (e.g., each week of feeding) should be constant.

Step2: List examples

Examples of constant variables:

1. The amount of food given to each puppy daily/weekly.
2. The initial mass of each puppy (if they start with similar masses).
3. The age of the puppies (if they are of the same age group).
4. The environment (e.g., same temperature, living conditions) for all puppies.

Step1: Define dependent variable

A dependent variable is what is measured/observed and depends on the independent variable. In this experiment, Dr. Vet measures the mass of puppies, which depends on the food formula (independent variable).

Step2: Identify the dependent variable

The mass of the puppies (in grams) at the end of each week is the dependent variable as it is the outcome being measured based on the food formula used.

Step1: Define independent variable

An independent variable is the factor that is changed/manipulated in an experiment to observe its effect on the dependent variable. Here, Dr. Vet is testing different food formulas.

Step2: Identify the independent variable

The independent variable is the type of puppy - food formula (since different formulas are used to see their effect on puppy mass).

Answer:

Examples of constant variables: amount of food per puppy, initial puppy mass, puppy age (or environment, etc.).

Part b