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Respiration Calculation

BIOLOGY

Animal Physiology

Driving Question: Which invertebrates do excrete CO2 and use the largest amount of glucose?

Introduction

Aerobe dissimilation is the process in the mitochondria in which enzymes convert glucose and oxygen into carbon dioxide and water to produce energy. In this activity, we will prove that carbon dioxide is indeed excreted when glucose is dissimilated. In addition, we will calculate the amount of glucose the invertebrate will use during the day by measuring the amount of used oxygen.

Material

In your investigations, you will use:

– Interface (Datalogger, CMA vincilab)– Oxygen gas sensor (BT59i)– CO2 detection capsule– Clear calcium hydroxide solution – scale– Water– Small invertebrate

Procedure

2. Open the coach activity ‘Respiration calculation’.3. If necessary calibrate the oxygen sensor with a value dependant of the humidity. A

detailed instruction is included in the manual.4. Take the cup with holes out of the detection capsule and fill the capsule with a layer

Respiration calculation - Student

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of calcium hydroxide solution (20 ml)5. Place back the cup in the capsule and place a small insect in the capsule. 6. Place the oxygen sensor on the capsule. Make sure the sensor closes the capsule

and start the measurement. 7. Calcium hydroxide is an indicator. Inspect after the measurements the water surface

in the capsule. What do you see and what does it mean?8. Look at the results of the oxygen sensor. What happened with the oxygen levels in

the capsule?9. Compose the chemical reaction formula of the respiration of glucose based on the

information found in questions 7 and 8.10. In the following questions, we will determine the amount of glucose the invertebrate

used. To do so we first need to determine the volume of the capsule. Take the oxygen sensor from the capsule and remove the invertebrate.

11. Place the capsule on the scale and tare the scale. Fill the capsule up with water.12. Read out the weight of the capsule filled with water and calculate the volume with

the density of water. (ρ= 1 g/cm3= 1 g/ml). The formula is V=mρ .

13. Use the read-out function in the graph the oxygen percentage at the start and end of the measurement.

14. Use the answers of question 12 and 13 to calculate the volume oxygen used by the insect.

15. The molar volume is equal for all gasses with the same pressure and temperature (Vm=22.5 dm3/mol = 22.5 ml/mmol). Calculate the amount of mole oxygen used by the invertebrate.

16. Calculate the amount of mole glucose used by the invertebrate, using the answers of question 8.

17. Calculate amount of used glucose in grams. Use the molar mass of glucose (180.16 g/mol).

18. Read out the time the measurement took from the graph. How much glucose would this invertebrate use for one day? Which percentage of its own bodyweight is this?

Resources

Coach Activity: Respiration calculation.cma7

Coach Result: Respiration calculation.cmr7

CMA Learning and Teaching Resources