STRUCTURED/APPLICATION/SKILL TYPE
The following diagram refers to an apparatus which is used to demonstrate a physiological process:
(a) What is the purpose of keeping potassium hydroxide solution in the test tubes X and Y?
(b) Why has the coloured water risen in tube 1?
(c) What is the purpose of keeping boiled peas soaked in a disinfectant in test tube Y?
(d) Name the biological process which causes the above rise.
(e) Define the biological process shown in the experiment.

Hint: Physiological processes are the interactions between organ structures, muscles, tissues, cells, and biomolecules to achieve the complex purpose of sustaining life. Photosynthesis and Cellular respiration are both physiological processes.

Complete answer:
(a) The test tubes X and Y contain potassium hydroxide, which reacts chemically with carbon dioxide and absorbs it to create a precipitate.

(b) Due to the creation of a partial vacuum inside tube 1, the coloured water rises. This occurs because the carbon dioxide produced by germinating seeds is soaked up by potassium hydroxide in the flask containing those seeds. As a result of the CO2 soaking, a partial vacuum is created, sucking the water up and raising the water level.

(c) As a control, test tube Y contains boiling peas soaked in disinfectant. The process of respiration will not take place in this test tube because the peas have been cooked, so it will take place in test tube X.

(d) Cellular respiration is the biological process that induces the above rise.

 (e) The mechanism by which energy is released from the breakdown of organic compounds (glucose) is known as cellular respiration. This usually occurs inside the mitochondria. Photosynthesis is the polar opposite of this process.

Note: Cellular respiration is a process that occurs in all organisms' cells. It can be found in both autotrophs like plants and heterotrophs like animals. The cytoplasm of cells is where cellular respiration starts and it ends in the mitochondria.

Since the energy in glucose cannot be utilised by cells until it is contained in ATP, cellular respiration is necessary for most organisms' survival. The process by which cells use oxygen to help them turn glucose into energy is known as aerobic cellular respiration.