Experiment to demonstrate the production of CO₂ in aerobic respiration:
1) Take small quantity of any seed (groundnut or bean seeds) and allow them to germinate by imbibing them. While they are germinating place them in a conical flask. A small glass tube containing 4 ml of freshly prepared. Potassium hydroxide (KOH) solution is hung into the conical flask with the help of a thread and tightly close the one holed cork (Figure).
2) Take a bent glass tube, the shorter end of which is inserted into the conical flask through the hole in the cork, while the longer end is dipped in a beaker containing water. Observe the position of initial water level in bent glass tube.
3) This experimental setup is kept for two hours and the seeds are allowed to germinate. After two hours, the level of water rises in the glass tube. It is because, the CO₂ evolved during aerobic respiration by germinating seeds will be absorbed by KOH solution and the level of water will rise in the glass tube.
CO₂+2KOH⟶K₂CO₃+H₂O

4)In the case of ground nut or bean seeds, the rise , of water is relatively lesser because these seeds use fat and proteins as respiratory substrate and release a very small amount of CO₂, But in the case of wheat grains, the rise in water level is greater because they use carbohydrate as respiratory substrate. When carbohydrates are used as substrate, equal amounts of CO₂ and O₂ are evolved and consumed.

Significance of pentose phosphate pathway:
1) HMP shunt is associated with the generation of two important products,NADPH and pentose sugars, which play a vital role in anabolic reactions.
2) Coenzyme NADPH generated is used for reductive biosynthesis and counter damaging the effects of oxygen free radicals
3) Ribose 5 phosphate and its derivatives are used in the synthesis of DNA, RNA, ATP, NAD+, FAD and coenzyme A.
4) Erythrose is used for synthesis of anthocyanin, lignin and other aromatic compounds.
5) It is characterized by the production of CO₂ and it is used for Carbon fixation in photosynthesis

During the Glycolytic pathway of respiration, 2, phospho glycerate is converted to phospho enol pyruvate. During this process, a molecule of water is removed by the enzyme enolase. This is called Enolation.

1) The conversion of pyruvate to ethanol takes place in malted barley and grapes through fermentation. Yeasts carryout this process under anaerobic conditions and this conversion increases ethanol concentration.
2) If the concentration increases, it's toxic effect kills yeast cells and the left out is called beer and wine respectively