life process

• Life processes in living organisms are necessary for maintaining their life
• The basic life processes are: nutrition, respiration, transportation, and excretion
• Nutrition is the process of taking food by an organism and its utilization by the body for life processes
• Respiration is the process by which food is burnt in the cells of the body with the help of oxygen to release energy
• Transportation is the process by which food, oxygen, water, waste products are carried from one part of the body to the other
• Excretion is the process by which waste products are removed from the body
• Modes of nutrition:

  • Autotrophic nutrition: organisms prepare their own food from simple inorganic substances like carbon dioxide and water in the presence of sunlight and chlorophyll
  • Heterotrophic nutrition: organisms get their food directly or indirectly from plants
• Photosynthesis is the process by which plants prepare food by using carbon dioxide and water in the presence of sunlight and chlorophyll
• Requirements of photosynthesis:

  • Carbon dioxide, water, chlorophyll, and Solar Energy (sunlight)
• Process of photosynthesis:

  • Absorption of light energy by chlorophyll
  • Conversion of light energy into chemical energy and splitting up of water molecules into hydrogen and oxygen
  • Reduction of carbon dioxide by hydrogen to form carbohydrates
• Heterotrophic nutrition:

  • Saprophytic nutrition: organisms get their food from dead and decaying organisms
  • Parasitic nutrition: organisms get their food from living organisms without killing them
  • Holozoic nutrition: organisms take food directly and then digest and absorb it
• Nutrition in amoeba:

  • Ingestion, Digestion, Absorption, Assimilation, Egestion
• Nutrition in paramecium:

  • Ingestion, Digestion, Absorption, Assimilation, Egestion
• Nutrition in Human beings:

  • Takes place in the digestive system consisting of the alimentary canal and glands
  • Main organs: mouth, oesophagus, stomach, small intestine, large intestine, and anus
  • Main glands: salivary glands, gastric glands, liver, pancreas, and intestinal glands
• Stomach:

  • Hydrochloric acid makes the medium acidic and helps in the action of pepsin
  • Mucous protects the walls of the stomach from the action of the acid
  • Food passes into the small intestine after being in the stomach
• Small Intestine:

  • Made up of three regions: duodenum, jejunum, and ileum
  • Receives partially digested food from the stomach
  • Duodenum receives bile from the liver, enzymes from the pancreas, and secretes some enzymes on its own
• Liver:

  • Largest gland in the human body
  • Helps in emulsification of fats
  • Converts acidic food coming from the liver into alkaline with bile juice
• Gallbladder:

  • Small pouch under the liver
  • Stores bile produced by the liver
• Pancreas:

  • Second largest gland in the human body
  • Produces pancreatic juice with enzymes such as Trypsin, pancreatic amylase, and pancreatic lipase
  • Trypsin helps in protein digestion, pancreatic amylase in carbohydrate digestion, and pancreatic lipase in fat digestion
• Small Intestine:

  • Glands in the walls produce intestinal juice
  • Enzymes in the intestinal juice convert carbohydrates into glucose, fats into fatty acids and glycerol, and proteins into amino acids
• Villus:

  • Finger-like outgrowths in the walls of the small intestine
  • Increase the surface area for absorption of digested food
• Large Intestine:

  • Water is absorbed and waste material is removed through the anus
• Respiration:

  • Process by which food is burnt in cells with the help of oxygen to release energy
  • Takes place in the mitochondria of cells
• Human Respiratory System:

  • Main organs include nostrils, nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, lungs, and diaphragm
  • Air enters through the nostrils and passes through the respiratory system
• Mechanism of Respiration:

  • When breathing in, diaphragm contracts and moves downward
  • When breathing out, diaphragm relaxes and moves upward
• Respiration in Animals:

  • Aquatic organisms have faster breathing due to low dissolved oxygen
  • Terrestrial organisms use oxygen in the atmosphere for respiration
• Transportation in Human Beings:

  • Circulatory system consists of blood, arteries, veins, capillaries, and heart
  • Blood transports food, oxygen, and waste products
• Blood Vessels:

  • Arteries carry pure blood from the heart, thick-walled and no valves
  • Veins carry impure blood to the heart, thin-walled and have valves
  • Capillaries connect arteries and veins, exchange of substances occurs through them
• Structure of Human Heart:

  • Muscular organ with four chambers
  • Atria and ventricles have valves to prevent backward flow of blood
• Hearts of Mammals, Birds, Amphibians, Reptiles, and Fishes:

  • Mammals and birds have four-chambered hearts
  • Amphibians and reptiles have three-chambered hearts
  • Fishes have two-chambered hearts
• Working of Heart:

  • Double circulation system
  • Oxygenated and deoxygenated blood flow through different sides of the heart
• Lymph:

  • Colourless fluid in intercellular spaces
  • Drains into lymphatic capillaries and vessels, then into large veins
• Transportation in Plants:

  • Xylem transports water and minerals
  • Phloem transports food through translocation
• Role of Transpiration:

  • Absorption and upward movement of water and minerals
  • Temperature regulation, cooling the plant body, removal of excess water
• Excretion:

  • Process of removing waste products from the body
  • Human excretory system consists of kidneys, ureters, urinary bladder, and urethra
• Dialysis:

  • Artificial kidneys for filtering waste products from blood
  • Blood passes through dialysing tubes for purification
• Excretion in Plants:

  • Gaseous waste products removed through stomata
  • Excess water removed through transpiration
  • Some waste products stored in leaves, vacuoles, or old xylem cells