CBSE Class 8 > Class 8 Notes > Year 8 Biology (Cambridge) > PPT - Respiration in Organisms
PPT - Respiration in Organisms
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Page 1 WHY DO WE RESPIRE? • All the living organisms are made up of small microscopic units called the cells. • These cells have different functions to perform in these organisms such as digestion, respiration, transportation and excretion. Page 2 WHY DO WE RESPIRE? • All the living organisms are made up of small microscopic units called the cells. • These cells have different functions to perform in these organisms such as digestion, respiration, transportation and excretion. • The cells can perform this function only if they get the energy to do so. • Hence, all living organisms need food which gives them the required energy. • The energy present in the food gets released when the organisms respire or breathe. Page 3 WHY DO WE RESPIRE? • All the living organisms are made up of small microscopic units called the cells. • These cells have different functions to perform in these organisms such as digestion, respiration, transportation and excretion. • The cells can perform this function only if they get the energy to do so. • Hence, all living organisms need food which gives them the required energy. • The energy present in the food gets released when the organisms respire or breathe. CELLULAR RESPIRATION Cellular respiration can be defined as the process in which the food that we eat is broken down inside the cells which results in the release of energy. All the cells in living organisms undergo cellular respiration. Page 4 WHY DO WE RESPIRE? • All the living organisms are made up of small microscopic units called the cells. • These cells have different functions to perform in these organisms such as digestion, respiration, transportation and excretion. • The cells can perform this function only if they get the energy to do so. • Hence, all living organisms need food which gives them the required energy. • The energy present in the food gets released when the organisms respire or breathe. CELLULAR RESPIRATION Cellular respiration can be defined as the process in which the food that we eat is broken down inside the cells which results in the release of energy. All the cells in living organisms undergo cellular respiration. The cellular respiration takes place in a cell organelle called mitochondria. The oxygen that an organism breathes in reacts with the carbohydrates (glucose) present in the food and results in the release of carbon dioxide, water and energy. Page 5 WHY DO WE RESPIRE? • All the living organisms are made up of small microscopic units called the cells. • These cells have different functions to perform in these organisms such as digestion, respiration, transportation and excretion. • The cells can perform this function only if they get the energy to do so. • Hence, all living organisms need food which gives them the required energy. • The energy present in the food gets released when the organisms respire or breathe. CELLULAR RESPIRATION Cellular respiration can be defined as the process in which the food that we eat is broken down inside the cells which results in the release of energy. All the cells in living organisms undergo cellular respiration. The cellular respiration takes place in a cell organelle called mitochondria. The oxygen that an organism breathes in reacts with the carbohydrates (glucose) present in the food and results in the release of carbon dioxide, water and energy.Read More
FAQs on PPT - Respiration in Organisms
| 1. What's the difference between aerobic and anaerobic respiration in organisms? |  |
Ans. Aerobic respiration requires oxygen to break down glucose and release energy, while anaerobic respiration occurs without oxygen and produces less energy. Aerobic respiration happens in mitochondria and yields approximately 38 ATP molecules, whereas anaerobic respiration in the cytoplasm produces only 2 ATP molecules. Both processes are essential for different organisms and environmental conditions.
| 2. Why do plants respire if they make their own food through photosynthesis? | |
Ans. Plants respire because photosynthesis produces glucose for growth, but respiration releases energy from that glucose to fuel all life processes like cell division, transport, and synthesis. Photosynthesis and respiration are distinct processes-one builds molecules while the other breaks them down for usable energy. Without respiration, plants cannot survive despite producing their own food.
| 3. How does breathing differ from cellular respiration in living organisms? | |
Ans. Breathing is the physical exchange of gases (oxygen in, carbon dioxide out) through the lungs or gills, while cellular respiration is the biochemical breakdown of glucose inside cells to release energy. Breathing supplies oxygen for respiration but is not respiration itself. Organisms can breathe but still respire aerobically or anaerobically depending on oxygen availability.
| 4. What happens to glucose during the stages of aerobic respiration? | |
Ans. Glucose undergoes three main stages: glycolysis (in cytoplasm, splitting glucose into pyruvate), the Krebs cycle (in mitochondria, breaking down pyruvate), and the electron transport chain (releasing maximum energy as ATP). Each stage extracts more energy from glucose molecules progressively. The complete oxidation of one glucose molecule yields approximately 38 ATP molecules for cellular energy.
| 5. Why do muscles produce lactic acid during intense exercise and how does it affect performance? | |
Ans. During intense exercise, muscles lack sufficient oxygen for aerobic respiration, so they switch to anaerobic respiration, producing lactic acid as a byproduct. Lactic acid accumulation causes muscle fatigue and soreness, temporarily reducing performance and endurance. Recovery occurs when oxygen becomes available again, allowing the liver to convert lactic acid back into glucose through gluconeogenesis.
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