Question

before you answer a question, identify the variables or the 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? c. what trends do you notice based on table 1? fill in the blanks: from 1991 to 1997, the average abundance of species k and species n while the average abundance of species m and species p then 2. based on table 1, as time elapsed from 1991 through 1997, the average abundance of species p: (circle where you found your response in the table, and put the question number next to it) a. decreased only. c. decreased and then increased b. increased only. d. increased and then decreased 3. in the study that produced the results shown in table 1, was year an independent variable or a dependent variable, and was average abundance an independent variable or a dependent variable? (circle where you found your response in the table, and put the question number next to it) a. year: independent; average abundance: independent b. year: independent; average abundance: dependent c. year: dependent; average abundance: independent d. year: dependent; average abundance: dependent

Explanation:

1.
a. The independent variable is the one that is changed or controlled in a scientific experiment. Here, the year is what is being changed (from 1991 - 1997), so the independent variable is year.
b. The dependent variable is the variable that is measured and changes in response to the independent variable. The average abundance of the species (number of organisms per cubic meter of water) is measured and depends on the year, so the dependent variable is average abundance (organisms/m³).
c. For Species K: 1991 (1050) - 1992 (1150) - 1993 (400) - 1994 (205) - 1995 (100) - 1996 (25) - 1997 (13). It first increased (1991 - 1992) then decreased (1992 - 1997). For Species N: 1991 (69) - 1992 (61) - 1993 (80) - 1994 (15) - 1995 (24) - 1996 (36) - 1997 (41). It first decreased (1991 - 1992), then increased (1992 - 1993), then decreased (1993 - 1994), then increased (1994 - 1997). For Species M: 1991 (2300) - 1992 (3100) - 1993 (1600) - 1994 (2200) - 1995 (2050) - 1996 (1000) - 1997 (800). It first increased (1991 - 1992) then decreased (1992 - 1997). For Species P: 1991 (200) - 1992 (250) - 1993 (320) - 1994 (410) - 1995 (1075) - 1996 (1000) - 1997 (500). It first increased (1991 - 1995) then decreased (1995 - 1997). So from 1991 to 1997, the average abundance of Species K and Species N first increased/decreased then decreased/increased (depending on the species - K: increased then decreased; N: decreased - increased - decreased - increased). The average abundance of Species M and Species P first increased then decreased.

1. Looking at Species P: 1991 (200) - 1992 (250) - 1993 (320) - 1994 (410) - 1995 (1075) - 1996 (1000) - 1997 (500). It increased from 1991 - 1995 and then decreased from 1995 - 1997. So the answer is d. Increased and then decreased.
2. As explained in 1a and 1b, year is the independent variable (it is the variable that is manipulated - the years are chosen for the study) and average abundance is the dependent variable (it depends on the year). So the answer is b. Year: independent; Average abundance: dependent.

Answer:

1.
a. Year
b. Average abundance (organisms/m³)
c. Species K: increased then decreased; Species N: decreased - increased - decreased - increased; Species M: increased then decreased; Species P: increased then decreased

1. d. Increased and then decreased
2. b. Year: independent; Average abundance: dependent