Biology, 13.08.2020 09:01 josh3419

Design a controlled experiment to test the effect of water temperature on goldfish. be sure to include your hypothesis, independent variable, dependent variable as well as experimental group and control group.

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Answer from: jfox8741

In this experiment, indepedent variable will be temperature and dependent variable will be the respiratory rate of goldfish. Temperature affects the respiratory rate of goldfish, as it's respiratory rate decreases with decrease in temperature of water, the experiment is as follows:

Take two glass containers filled with water A and B and put one goldfish in each container.Measure the temperature of the water using a thermometer.Count mouth movement of both the fishes in certain time.Now put some ice in container B that will decrease the temperature of water and measure the temperature again.Now count the mouth movement of both the fishes for the same time it was counted earlier.

The result will be that respiratory rate of goldfish decreases with the decrease in temperature in container B in comparison to container A goldfish.

Answer from: branj1317

An experiment meant to determine the cause of an effect, the effect is the independent variable, while the cause is the dependent variable

A controlled experiment to test the effect of water temperature on goldfish is designed as follows:

The experimental group are: The gold fish in a glass Jar X filled with fresh water and with the lid left open (the treatment of temperature reduction is applied to the experimental group)

The control group are: A second gold fish (selected at random) of the same size, in another glass jar Y filled to the same level with fresh water collected from the same source of the first gold fish

Independent variable: The independent variable is the temperature of the water which will be varied by placing ice cube gradually into the glass jar B

Dependent variable: The number times the gold fish gulp air by rising to the surface, and or the number of time goldfish opens its mouth, which indicates that the goldfish is breathing

The hypothesis: The breath rate of goldfish decreases with decrease in temperature because the goldfish metabolic rate decreases and the water holds more dissolved air and therefore oxygen at a reduced temperature

The Experiment Design:

The experiment is conducted by measuring the initial temperature and breathing rate of both fishes

The temperature of the fresh water in jar X is decreased gradually by adding ice cubes and recording the temperature and breathing rate of the goldfish

A similar experiment from an online source (Maryland School improvement website) the following results where obtained

$\begin{array}{|c|cc|} \underline {Breathing \ rate}&&\underline {Water \ Temperature } \\&&\\ (Dependent \ Variable)&&(Independent \ Variable)\ \\&&\\103&&78.8 ^{\circ}F\\78&&68^{\circ}F\\55&&57.2^{\circ}F\\28&&46.4^{\circ}F\\4&&35.6^{\circ}F\end{array}\right]$

From the experiment, it can be seen that the in the experimental group dependent variable, which is the breathing rate of the goldfish reduces as the temperature which is the dependent variable is reduced

Learn more about experimental variables here:

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