Question

Aerobic Cellular Respiration In Beans lab experiment

1. What caused the bromothymol blue in some of the beakers to change colors?

2. What metabolic process was occurring in the beans that produced a color change?

3. What was the purpose of soaking some of the beans first?

4. What was the purpose of soaking some of the beans first?

4. What was the purpose of preparing some beakers with no beans?

Answer 1

Question 1)

Bromothymol blue changed colour due to the increasing concentration of Carbon Dioxide CO₂. Thus CO₂ is responsible for the colour change.

Explanation:-

Bromothymol blue is a pH indicator. It changes its colour when added into a reaction mixture as pH of the solution gets more acidic and that is why it is used to measure the activity of photosynthesis and respiration in the cell. When the pH turns acidic, it turns Yellow and indicates accumulation of the products of the respiration.

Question 2:-

Since bromothymol blue is a pH indicator of aerobic respiration, the colour change in the beaker with soaked beans it indicates the cellular respiration. Thus, the process which is taking place is Aerobic respiration or to be specific, Oxidative phosphorylation as it is this process which generates Carbon dioxide.

Question 3:-

Beans are soaked before setting up the experiment because dry beans are dormant, so to make them metabolically active we soaked them.

Explanation:-

In dry seeds, there is no water content and that work as a preservation condition since enzymes which are responsible for the breakdown of the substrate available inside the cells are active when there is water available. Water is required by the enzyme as they need water in their environment to be properly folded in the conformation which is suited for their activity.

Question 4:- What was the purpose of preparing some beakers with no beans?

The beakers with no beans serve as the control for the experimental setup. The purpose of the control is to test the experimental design and also to prove if the hypothesis is wrong or right. In this setup, we are using the empty beakers as a control to test and to make sure that the colour changed observed is due to the beans respiration, not because of the environment or some other factors like contamination.

If there is no colour change in the control, this means that the experiment was conducted without any error and the colour change is due to the seeds respirating.