Question

Sam wished to investigate how fertilizer run-off affects the growth of algae in freshwater lakes and streams. He set his experiment up as follows. He placed 900 ml of water into each of five 1000 ml glass beakers. To each beaker, he added 5 ml of water from an aquarium which contained a large concentration of algae. The beakers were placed under a lamp which was on a timer to provide 12 hours of light each day. Liquid fertilizer was added to the beakers in the following amounts.

Beaker -

A - 8 ml

B - 6 ml

C - 4 ml

D - 2 ml

E - 0

Each week, a random sample from each of the beakers was examined under a microscope to get a count of the number of algal cells present.\

hours of daylight



size of beakers

amount of fertilizer

amount of aquarium water

What is the

Independent Variable -
Dependent Variable -

Which of the following is NOT a controlled variable in this experiment?

Which of the following is the control group for the experiment?

Answer 1

amount of alagal cells

Step-by-step explanation:

Answer 2

Part 1.

The independent variable in this experiment is the amount of fertilizer given to algae in different beakers.

Step-by-step explanation:

• An independent variable in the experiment can be defined as the input of experiment which can be changed.
• Like the amount of fertilizer can be changed independently.
• This amount is not depend on anything while results depends on it.

Part 2.

The dependent variable in the experiment is the growth of algae in beakers, Concentration of algae.

Step-by-step explanation:

• Usually dependent variable in experiment are the outputs of experiments and these are dependent on the the independent variable of experiment.
• Here growth of algae depends on the amount of fertilizer. so it is independent variable.

Part 3.

The option C is not the controlled variable in this experiment which is amount of fertilizer.

Step-by-step explanation:

• A controlled variable is a variable which is kept constant throughout the experiment.
• It actually don't concerns with the experiment results but if it is effected it can change the correlation between Independent Variable and Dependent Variable.

Part 4.

The option A, B and D are the control group for the experiment which are hours of daylight and size of beakers , amount of aquarium water.

Step-by-step explanation:

• In this experiment these above given things remain throughout the experiment.
• A controlled variable is a variable which is kept constant throughout the experiment.

• It actually don't concerns with the experiment results but if it is effected it can change the correlation between Independent Variable and Dependent Variable.