Question

reviewing the living environment: biology
phosphorus concentrations
which statement represents a valid conclusion based on information in the graph?
1 there was a decrease in the amount of phosphorus dumped at site 2 from 1991 to 1997.
2 pollution controls may have been put into effect at site 1 starting in 1995.
3 there was most likely no vegetation present near site 2 from 1993 to 1994.
4 there was a greater variation in phosphorus concentration at site 1 than at site 2.

1. the concentration of salt in

Explanation:

1. Analyze each statement:

• Statement 1: The graph shows an overall increase in phosphorus concentration at Site 2 from 1991 - 1997, so it's false.
• Statement 2: Phosphorus concentration at Site 1 starts to decline from 1995, which could be due to pollution - control measures being implemented. This is a valid conclusion.
• Statement 3: The graph gives no information about vegetation near Site 2, so this is an invalid conclusion.
• Statement 4: The variation in phosphorus concentration at Site 2 is similar to that at Site 1, so this is false.

Answer:

1. Pollution controls may have been put into effect at Site 1 starting in 1995.