Question

Darwin's experiments are just one way to study phototropism. A student wants to investigate the effects of phototropism in bean plants. She places a light source directly above one plant, at a forty‐five degree angle to another, and at a ninety‐degree angle from the third.

What is her independent variable?

What is a hypothesis she might write for her experiment?

Answer 1

The independent variable is the angle of the light source in relation to the bean plants. A hypothesis the student might write for the experiment is provided.

Step-by-step explanation:

The independent variable in the student's experiment is the angle at which the light source is placed in relation to the bean plants. The three angles chosen - directly above, at a forty-five degree angle, and at a ninety-degree angle - represent the different treatments used in the experiment.

A hypothesis the student might write for this experiment could be: 'If the angle of the light source affects phototropism in bean plants, then the plant with the light source directly above will exhibit the greatest bending towards the light, followed by the plant with the light source at the forty-five degree angle, and the plant with the light source at the ninety-degree angle will exhibit the least bending towards the light.'

Answer 2

The independent variable is what is being changed or altered in the experiment (light position), the dependant variable is what is altered or changed by the independent variable (plant).

Step-by-step explanation:

Consider what is being changed in this experiment to investigate the effects? The plant itself is not changed by the experiment but the positioning of the light source is. That is your independent variable. The plant may change as a result of the independent variable but isn't being altered or changed as part of the method (dependent).

What is a hypothesis she might write?

Consider a hypothesis as a prediction. Researchers come up with their hypothesis based on the information they already know. So to write your hypothesis think about what you already know about phototropism. What do you think will happen to the plant in relation to the positioning of the lamp? Will the plant not move? Will it bend or move to face the lamp?

Hope this helps.