Name: Respiration in Hydra and Grasshopper
Uploaded: 2019-07-19
Duration: 7 min 16 s
Description: Hydra look like they are all over the place. Well, their respiration definitely is; through the general body surface! What about respiration in the grasshopper?

Question

Plan an investigation to test the below hypothesis:

'Germinating peas respire faster as temperature increases, up to an optimum'.

Think carefully about controlling variables, what you will measure and when, and how you will keep yourself and others safe. Describe how you will record, display and interpret your results. Predict what the results will be if the hypothesis is correct.

Accepted Answer

Objective: To check the hypothesis 'Germinating peas respire faster as temperature increases, up to an optimum'.

In order to check this hypothesis, we have to measure the rate of cellular respiration for germinating peas by measuring the rate of exchange for oxygen. When germinating seeds consume oxygen, carbon dioxide will be liberated through the oxidation or breakdown of nutrients (carbohydrate/fat/protein). In this experiment, a microrespirometer will be used, which will measure the rate of respiration of the germinating seed.

Steps followed to perform the experiment:

At first, we have to set up the control in which the plunger is removed from a prepared respirometer. Then it is labelled with "CR" or "CH" respectively, depending on whether it is the 'control room temperature' or 'heated treatment'.

Then glass microbeads are added to each of the microrespirometers up to the 0.5 mL mark, and the plunger is pushed in the syringe to the 1 mL mark.

Then 3 - 4 washers onto the flared end of each microrespirometer are added to weigh microbeads down while in the water bath.

Then control devices are set to the side.

To set up the experimental seated respirometers, the plunger is removed from a prepared microrespirometer and labelled with "ER" or "EH" respectively, depending on whether it is the 'experimental room temperature' or 'heated treatment'.

Then 0.5 mL of germinating seeds is measured into the tuberculin syringe of the microrespirometer.

After that, the syringe is pushed to the 1 mL mark.

Then 3 - 4 washers are placed onto the flared end of each microrespirometer to weigh them down while in the water bath.

Then to use the microrespirometers, "CR" and "ER" microrespirometers are pressed into the room temperature water bath. (Note: The whole syringe should be submerged, but the capillary tubes should be entirely exposed.)

Then water from the bath is removed, making sure the top of the capillary tube is open.

The same procedure is performed for the "CH" and "EH" microrespirometers to set up the higher temperature experimental group.

Then we need to wait 5 minutes before moving on to allow the temperature in the microrespirometers to equalize with the water bath.

Then a single drop of manometer fluid is added to the top of each of the four capillary tubes, which seals the microrespirometer chambers. (NOTE: The manometer fluid will be sucked into the capillary chamber if the chambers are working properly.)

The plunger is set in the bath to suck the manometer fluid into the capillary. The flowing of the bath is stopped when the fluid is about halfway down the capillary tube. After this setup, the microrespirometer should not be disturbed.

Then the bottom edge of the manometer fluid, which is closer to the chamber, is marked. This marked point represents time point zero.

After 5 minutes, a new mark is created where the manometer fluid is on each microrespirometer.

This marking is repeated every 5 minutes until 25 minutes has passed or until the manometer fluid has travelled the entire length of the capillary tube.

After that, respirometers from the water baths are removed. Then the distance between each of the marks is measured.

Temperature is an external factor essential for respiration. A germinating is expected to utilize more energy because it is required to grow and develop. The germinating seeds respire rapidly to fulfil their need for energy. Through this experiment, we can measure the rate of respiration by measuring the amount of carbon dioxide liberated. The carbon dioxide will be absorbed by potassium carbonate resulting in the gradual reduction of overall gaseous pressure in the respirometer. Thus, after 25 minutes, the gaseous pressure must have reduced, which indicates the liberation of high respiration.

Important Questions on Respiration and Gas Exchange

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