Respiration of Class 7
When cells carry out break down of nutrients without utilizing molecular oxygen; the process is called anaerobic respiration. A number of micro-organisms including yeast derive energy through anaerobic respiration. Louis PasteurFounder of microbiology, discovered the role of bacteria in fermentation. He disproved the theory of spontaneous generation and developed the technique of pasteurization.
It involves two steps :
- Glycolysis :It is similar to glycolysis of aerobic respiration except that aerobic glycolysis produces 2 ATP and 2 NADH2. (Aerobic glycolysis is 4 times more efficient than anaerobic glycolysis.)
- During anerobic respiration 1 molecule of glucose (food) produces only 2 energy-rich ATP molecules. A few organsims such as yeast plants and certain bacteria can obtain energy from food in the absence of oxygen by the process of anaerobic respiration. All the cells do not use oxygen to produce energy. Energy can be produced in cells even without oxygen.
- Anaerobic breakdown of pyruvic acid :Depending upon the organism, type of tissue and nature of end product, anaerobic respiration or fermentation is of following types :
- Alcoholic fermentation :It is that fermentation where product is ethyl alcohol and CO2& two molecules of ATP are formed.
- Lactic acid fermentation : It is that fermentation where sugar is converted into lactic acid.
NCERT SOLUTION FOR CLASS-7 SCIENCE (Science for grade-7 NCERT solutions)