Cellular Respiration Lab Walkthrough

Summary

In this instructional video, Mr. Andersen guides viewers through a cellular respiration lab experiment. He details the materials needed, such as germinating and non-germinating peas, glass beads, and potassium hydroxide, explaining how to prepare respirometers. The process involves measuring the oxygen consumption of germinating peas compared to non-germinating peas by observing changes in water levels in pipettes. Throughout, Mr. Andersen emphasizes careful measurement and the importance of maintaining controlled conditions to accurately assess respiration rates. This lab provides a hands-on experience for understanding the principles of cellular respiration.

Takeaways

• 🧪 Step 1: Gather three vials with steel washers at the bottom for the experiment.
• 💧 Fill a graduated cylinder with approximately 50 ml of water for measurements.
• 🌱 Add 15 germinating peas to the water and measure the volume change.
• 🔍 Ensure to document the volume of germinating peas (approximately 7 ml).
• ⚖️ Repeat the process for glass beads to match the volume of the peas.
• ❌ Use non-germinating peas and adjust with glass beads to reach a total of 7 ml.
• 🧼 Construct a respirometer using absorbent and non-absorbent cotton with potassium hydroxide.
• ⏱️ Allow an equilibration period of 10 minutes for temperature stabilization.
• 💧 Immerse the respirometers in water, ensuring pipettes remain above water for accurate measurements.
• 📏 Record oxygen consumption and carbon dioxide production at specific time intervals (0, 5, 10, 15, and 20 minutes).

Q & A

What is the first step in the cellular respiration lab?

The first step is to obtain three vials with steel washers on the bottom.

How much water should be filled in the graduated cylinder?

Approximately 50 ml of water should be filled in the graduated cylinder.

What should be added to the water in the graduated cylinder?

Fifteen germinating peas should be added to the water.

How do you determine the volume of germinating peas?

You measure the change in volume after adding the peas to the water; it should increase by about 7 ml.

What is the purpose of the glass beads in the experiment?

Glass beads are used to ensure the same volume is maintained and to account for temperature changes.

What is the significance of potassium hydroxide in the experiment?

Potassium hydroxide absorbs carbon dioxide produced during respiration, turning it into a solid.

What safety precautions should be taken when handling potassium hydroxide?

You should avoid contact with eyes and skin as it is a poisonous substance.

What should be done during the equilibration period?

The respirometers should be placed under water for about 10 minutes to ensure the temperature inside matches the water temperature.

How do you measure the respiration rates in the respirometers?

You record the initial amount in each pipette and then measure the levels at 5, 10, 15, and 20 minutes.

What happens to the water levels in the pipettes during respiration?

As the organisms consume oxygen and produce carbon dioxide, the water levels will rise in the pipettes due to the absorption of carbon dioxide by potassium hydroxide.