Question

- Read the following hypothesis

- Write the independent and dependent variables that would be used in an experiment designed to test each hypothesis.

- Establish an experimental control/control for each hypothesis

- Establish a positive and negative control for each hypothesis

- Identify a controlled variable for each hypothesis

1. If the concentration of salts in solution surrounding the red blood cell is related to the osmotic pressure in the red blood cell, then decreasing salt concentrations of the solution will cause the cell to swell and burst.

2. If the amount of enzyme is related to the rate of the chemical reaction, then increasing the amount of enzyme will increase the speed of the reaction.

3. If the type of sugar provided to growing yeast is related to the amount of alcohol produced by the yeast, then growing yeast in different sugars will result in different amounts of alcohol produced.

4. If the time under UV light is related to bacterial death, then increasing the time under UV light will increase the number of bacteria killed.

Answer 1

1.INDEPENDENT VARIABLE-it is the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable.

DEPENDENT VARIABLE- it is the variable that is tested and measure in a scientific experiment.

• In hypothesis 1,the salt concentration is the independent variable where as, osmotic pressure is the dependent variable.Because salt concentration can be manipulated according to the osmotic pressure but osmotic pressure is measurable and can be tested.
• In hypothesis 2,amount of enzyme is the independent variable,where as the rate of chemical reaction is the dependent variable
• In hypothesis 3,type of sugar is the independent variable,where as the amount of alcohol is the dependent variable
• In hypothesis 4,time is the independent variable and the number of bacterial death is the dependent variable

2.EXPERIMENTAL CONTROL-The experimental control or control group is a set of object or population which is statistically similar to the group that is being tested.A control is used as a standard of comparison for checking the result of an experiment.

• In hypothesis 1,solution with out salt concentration is the experimental control.
• In hypothesis 2,chemical reaction with out enzyme is the control group.
• In hypothesis 3,growing yeast with out sugar is the control group
• In hypothesis 4,there is no experimental control

3.POSITIVE CONTROL-It is the experimental control that gives the positive result at the end of the experiment

NEGATIVE CONTROL-It is the experimental control that does not give a response to the test

• In hypothesis 1,solution with salt concentration is the positive control,whereas the solution with out salt concentration is the negative group
• In hypothesis 2,chemical reaction with enzyme is the positive control and with out enzyme is the negative control
• In hypothesis 3,growing yeast with sugar is the positive group,where as the yeast with out sugar is the negative group
• In hypothesis 4,there is no positive and negative controls

4 CONTROLLED VARIABLE

• controlled variable is one that must be kept constant for a fair test,you must make sure that you keep control variable constant throughout your experiment to ensure that you are carrying out a fair test
• In hypothesis 1,volume of solution surrounding the red blood cell is the controlled variable
• In hypothesis 2,type of chemical reaction is the controlled variable
• In hypothesis 3,amount of sugar and yeast is the controlled variable
• In hypothesis 4,quantity of uv light, is the controlled variable