6. LIFE PROCESSES
Experiment to prove release of CO2 during respiration in human
- Take some freshly prepared lime water in 2 test tubes.
- In one, blow air through lime water. It immediately turns lime water milky.
- In other test tube, pass air using a syringe or pichkari. It takes much time to turn the lime water milky.
- It shows that the breath-out air contains more CO2 as compared to atmospheric air.
Experiment to prove release of CO2 during respiration in Yeast
- Add some yeast to fruit juice or sugar solution. Take this mixture in a test tube fitted with a one-holed cork.
- Fit the cork with a bent glass tube. Dip its free end into a test tube containing freshly prepared lime water.
- Air taken out through the tube makes lime water milky. It is due to the production of CO2 in the mixture of yeast & sugar solution. Here, fermentation occurs.
Anaerobic respiration: It is the respiration in the absence of air (oxygen). It releases less energy. E.g.
- In yeast, the pyruvate is converted into ethanol & CO2. It occurs during fermentation.
- Sometimes, when there is no oxygen in our muscle cells, the pyruvate breaks down into lactic acid (3-carbon). This build-up of lactic acid in muscles during sudden activity causes cramps.
ATP is used to fuel all other cellular activities. When the terminal phosphate linkage in ATP is
broken using water, energy (30.5 kJ/mol) is released. It drives
the endothermic reactions in the cell.
Gas exchange in plants:
It occurs through stomata. Here, CO2 & oxygen are exchanged by diffusion. The large intercellular spaces in leaves help the cells in contact with air.
During day, CO2 formed by respiration is used for photosynthesis. So, CO2 is not released but oxygen is released. At night, photosynthesis does not occur. So, CO2 is released out but oxygen is not released.
Gas exchange in animals:
Aquatic animals breathe dissolved oxygen in water.
In fishes, the respiratory organ is gills with gill slits behind their eyes. They may be covered by operculum.
During breathing, fishes open and close mouth & gill slits (or operculum) in a coordinated manner and timing. They take in water through mouth and pumps over the gills. From the gills, dissolved O2 is taken up by blood.
The amount of dissolved O2 is lower than that in the air. So, the rate of breathing in aquatic organisms is faster than that in terrestrial organisms.
In terrestrial animals, there are different types of organs to breathe atmospheric oxygen. They increase surface area which is in contact with the atmosphere.
Surface of respiratory organs is very fine and delicate for easy gas exchange. To protect this surface, it is placed within the body. So, some passages are necessary to carry air in and out of respiratory organ.
Human respiratory system
It involves lungs & air passage.
Tobacco or tobacco products affect tongue, lungs, heart and liver. Smokeless tobacco also causes heart attacks, strokes, pulmonary diseases & cancers.During the breathing cycle, the lungs always contain a residual volume of air so that there is sufficient time to absorb oxygen and release CO2.
Oral cancer is highly reported in India due to tobacco chewing in the form of gutkha.
Smoking destroys cilia on the upper respiratory tract. As a result, germs, dust, smoke etc. enter lungs and cause infection, cough & lung cancer (common cause of death).