Life processes


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Gives information about the life processes.

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Life processes

  1. 1.  Various functions carried out by living beings; which are necessary to maintain and continue life are called life process.
  2. 2.  Nutrition  Respiration  Transportation  Excretion  Movement  Reproduction
  3. 3.  The process of taking in food and utilizing it is called nutrition.  The term ‘nutrition’ comes from the word ‘nutrient’.  A nutrient is an organic or inorganic substance required for the maintenance of life and survival of a living organism.  The food taken in by an organism contains a large number of nutrients like carbohydrates, fats, proteins
  4. 4.  Autotrophic 1. Photosynthesis 2. Chemosynthesis  Heterotrophic 1. Parasitic 2. Holozoic 3. Saprophytic
  5. 5.  The word ‘auto’ means ‘self’ and ‘trophe’ means ‘nutrition’.  Autotrophic nutrition is that mode of nutrition in which an organism makes its own food from the simple organic materials like carbon dioxide and water present in the surroundings (with the help of sunlight energy)  Those organisms which can make their own food from carbon dioxide and water are called autotrophs.
  6. 6.  Green plant are autotrophs and synthesis their own food by the process of photosynthesis.  ‘Photo’ means light and ‘synthesis’ means build, thus photosynthesis means ‘build up by light’.  The process by which green plants make their own food from carbon dioxide and water by using sunlight energy in the presence of chlorophyll is called photosynthesis.  Raw material required are carbon dioxide and water.  Oxygen gas is released during photosynthesis.
  7. 7.  The process of photosynthesis takes place in the green leaves of a plant.  The food prepared by the green leaves of a plant is in the form of a simple sugar called glucose.  The extra glucose is changed into another food called starch.  The green plants convert sunlight energy into chemical energy by making carbohydrates (food).  Site of photosynthesis is Chloroplasts. 6CO2 + 6H2O + Light Energy ---- C6H12O6 + 6CO2
  8. 8.  The photosynthesis takes place in the following four steps : 1. Absorption of sunlight energy by chlorophyll. 2. Conversion of light energy into chemical energy. 3. Splitting of water molecules into hydrogen and oxygen by light energy. 4. Reduction of carbon dioxide to form carbohydrates like glucose by utilising the chemical energy.
  9. 9.  The conditions necessary for photosynthesis to take place are: 1. Sunlight 2. Chlorophyll 3. Carbon Dioxide 4. Water
  10. 10.  The word ‘heteros’ means other and ‘trophe’ means nutrition, thus heterotrophic means nutrition obtained from others.  All animals have a heterotrophic mode of nutrition.  Those organisms which cannot make their own food from inorganic substance like carbon dioxide and water depend on other organism for their food are called autotrophs.
  11. 11.  Saprotrophic Nutrition  Parasitic Nutrition  Holozoic Nutrition
  12. 12.  Saprophytic nutrition is that nutrition in which an organism obtains its food from decaying organic matter of dead plants, dead animals, and rotten bread, etc.  Saprophytes are the organisms which obtain their food from dead plants, dead and decaying animal bodies, and other decaying matter.  Saprotrophic nutrition is also called saprophytic nutrition.  E.g. Mushroom, yeast, etc.
  13. 13.  The parasitic nutrition is that nutrition in which an organism derives its food from the body of another living organism (called its host) without killing it.  A parasite is a organism which feeds on another living organism called its host.  E.g Cuscuta, Plasmodium, etc
  14. 14.  Holozoic nutrition means ‘feeding on solid food’.  The holozoic nutrition is that nutrition in which an organism takes the complex organic food material into its body by the process of ingestion, the ingested food is digested and then absorbed into the body cells of the organism.  E.g. Amoeba, frog, etc.
  15. 15.  Animals obtain their food from plants and animals thus are heterotrophs.  Animals can be divided into three groups on the basis of their food habits: 1. Herbivores 2. Carnivores 3. Omnivores
  16. 16.  The nutrition in human beings takes place through human digestive system  The human digestive system consists of the alimentary canal and its associated glands.  The various organs of the human digestive system in sequence: Mouth, Oesophagus, Stomach, Small Intestine, and Large Intestine.  The glands which are associated with the human digestive system and form a part of the human digestive system are: Salivary Glands, Liver, and Pancreas.
  17. 17.  The process of releasing energy from food is called respiration.  The process of respiration involves taking in oxygen into the cells, using it for releasing energy by burning food, and the eliminating the waste products from the body.  Food + Oxygen ----- Carbon Dioxide + Water + Energy  Respiration is essential for life because it provides energy for carrying out all the life processes which are necessary to keep the organisms alive.
  18. 18.  The respiration which uses oxygen is called aerobic respiration