Ecologists designed an experiment to determine if nitrates or phosphates are more limiting to algae growth. They divided a lake in Canada into two equal-sized sections by a vinyl curtain. Then they fertilized each sub-basin of the lake, one with nitrates and carbon, and the other with phosphates, nitrates and carbon. The amount of phytoplankton in the lake was then measured in each side, with the side of the lake with phosphates added showing a greater rate of phytoplankton growth.
1. Frequently, studies in nature are difficult to set up and may lack some aspects of more traditional laboratory-based experiments. What element of this experiment could be considered lacking?
A) dependent variable
B)control
C)constants
D)repeated trials
E)independent variable
MY ANSWER IS D.
2. What is the independent? I put the phosphate added to one side of the lake
3. Constant?
a. depth of the lakes
b. the nitrate and carbon added to both lakes
c. the amount of phosphate added
d. the amount of phytoplankton growth
e. the species of fish in both lakes compared to other lakes
MY ANSWER IS B....or is it A?
4. What concept below best describes the process being studied in this experiment?
a. the greenhouse effect
b. cultural eutrophication
c. denitrification in response in fertilizers
d. red tide events
e. acid rain deposition
4. my answer is B
The correct answers to the questions are as follows:
1. The element of this experiment that could be considered lacking is E) independent variable. In the given experiment, only one type of independent variable (either nitrates or phosphates) was tested at a time, making it difficult to determine the specific effects of each factor.
2. The independent variable in this experiment is the addition of phosphates to one side of the lake.
3. The constant in this experiment is B) the nitrate and carbon added to both lakes. By keeping the amount of nitrate and carbon constant in both sides of the lake, the researchers can isolate the effects of the phosphates.
4. The concept that best describes the process being studied in this experiment is B) cultural eutrophication. Cultural eutrophication refers to the excessive enrichment of water bodies with nutrients, such as nitrates and phosphates, leading to increased growth of algae and other aquatic organisms. This phenomenon is often caused by human activities, such as the use of fertilizers in agriculture or the discharge of wastewater containing high nutrient loads.
1. The correct answer is B) control. In this experiment, there is only one treatment group (phosphate added) and one control group (nitrates and carbon added). However, a more traditional laboratory-based experiment would typically include additional control groups to compare the effects of different factors without any fertilizers added. This is done to ensure that any observed changes in the experimental group can be attributed specifically to the factor being tested.
2. The correct answer is the phosphate added to one side of the lake. The independent variable is the factor being manipulated by the researchers to observe its effect on the dependent variable (phytoplankton growth). In this experiment, the independent variable is the presence or absence of phosphates.
3. The correct answer is C) the amount of phosphate added. Constants are the variables that are kept the same throughout the experiment to ensure that only the independent variable is affecting the dependent variable. In this case, the depth of the lakes (A) and the nitrate and carbon added to both lakes (B) are parameters that are kept constant. However, the amount of phosphate added (C) is the specific factor being varied as the independent variable. The amount of phytoplankton growth (D) is the dependent variable, meaning it is being measured and expected to change as a result of the independent variable. The species of fish in both lakes compared to other lakes (E) is not mentioned as a relevant factor in this experiment.
4. The concept that best describes the process being studied in this experiment is B) cultural eutrophication. Cultural eutrophication refers to the process of excess nutrients, such as phosphates and nitrates, entering bodies of water, leading to an overgrowth of algae or phytoplankton. In this experiment, the researchers are determining if nitrates or phosphates are more limiting to algae growth, which is directly related to the process of cultural eutrophication. The other options listed (the greenhouse effect, denitrification in response to fertilizers, red tide events, and acid rain deposition) are all different environmental processes that are not directly related to this experiment.