Question

annotation guidelines

• before you answer a question, identify the variables on the x axis and y axis, the independent and dependent variables, and the trend(s) that you observe
• read a question first, then look back at the text, data tables, and graphs (and the captions next to them)
• you must circle where you are finding all of the answers, and put the question number next to it

the spiny water flea called b. longimanus is a nonnative species in harp lake, canada. scientists conducted a study to determine the average abundance (number of organisms per cubic meter of water) of 4 different species (species k, m, n, and p) of zooplankton in harp lake before and after b. longimanus were introduced in 1993. table 1 lists the average abundance for each species each year from 1991 through 1997.

1. take a look at table 1 and answer the following:

a. what is the independent variable?
________________________
b. what is the dependent variable?
________________________
table 1
note: from 1991 through 1997, the lake had an average annual ph of 6.3.
table adapted from the article \changes in zooplankton and the phenology of the spiny water flea, bythotrephes, following its invasion of harp lake. ontario, canada\ by norman d. yan et al. (©2001 by nrc canada).

Explanation:

• Independent variable: The variable that is changed or controlled in a scientific experiment. In this study, the factor that is manipulated (by the introduction of B. longimanus in 1993) and is represented on the x - axis (if we were to graph this data) in terms of time progression (years from 1991 - 1997) is the year.
• Dependent variable: The variable that is measured in an experiment. Here, it is the quantity that responds to the change (introduction of B. longimanus). The average abundance (number of organisms per cubic meter of water) of the 4 species (Species K, M, N, and P) is what is being measured.

Answer:

a. Year
b. Average abundance (organisms/m³) of Species K, M, N, and P