life processes

• Photosynthesis is the process by which plants convert sunlight, carbon dioxide, and water into glucose and oxygen.
• Process of photosynthesis:

  ->absorption of light energy by chlorophyll.

  ->light energy converts into chemical energy.

  ->splitting of water molecules into hydrogen and oxygen.

  ->reduction of carbon dioxide into carbohydrates.
• Stomata:

  ->present on the pores of the leaves.

  ->helps in exchange of gases.

  ->opening and closing of stomata depends on guard cells.

  ->when guard cells shrink the stomata closes and when guard cells swell stomata opens.
• Nutrition in amoeba:

  Ingestion- Ingests food by pseudopodia. When food comes near amoeba its forms a temporary finger like projections.

  Digestion-Food enters into the food vacuole where various digestive enzymes act on the food.

  Absorption-The digested food in absorbed directly into cytoplasm.

  Assimilation-Absorbed food is used to make energy by respiration. Remaining makes the whole amoeba cell which leads to growth.

  Egestion-Undigested food is thrown out of the body through an opening.
• Parts of human digestive system are: mouth, esophagus, stomach, small intestine, large intestine.
• Process of digestion in humans starts from mouth.
• Mouth-When the food enters the mouth, it is crushed by teeth and mixes with saliva. Saliva contains an enzyme called salivary amylase which breaks down starch into simple sugars.
• Oesophagus- After the mouth, the food is transported to the stomach by through the food pipe.
• Stomach:

  -> Expands when food enters.

  ->Muscular walls of the stomach helps in mixing the digestive juices.

  ->Digestion in stomach is taken care by the gastric glands present in the walls of the stomach.

  -> These walls release hydrochloric acid, pepsin, mucus.

  -> Hydrochloric acid creates an acidic medium in the stomach which helps the enzyme pepsin to act on it. It also kills the bacteria present in the food.

  ->Pepsin is a protein digesting enzyme.

  -> Mucus protects the walls of the stomach from the hydrochloric acid.
• From the stomach food enters into the small intestine.
• Small intestine:

  • Longest part of the alimentary canal.
  • Its length is different in different animals because herbivores animals eats grass and need a longer small intestine to allow cellulose to digest. Whereas, meat digests easily, so it does not require a longer small intestine.
  • Site of complete digestion of fats, carbs and protein. It receives secretion of liver and pancreas for this purpose.
  • The food coming from stomach is acidic in nature and has to be alkaline for the pancreatic enzymes to act on it.
• • Liver secretes bile. Bile salts breaks the fats present in the food into smaller molecules making it easy for the enzymes to act and digest them.
  • Pancreas secretes pancreatic amylase, trypsin and lipase.
  • The enzyme amylase breaks down starch.
  • Trypsin digests protein.
  • Lipase breaks fat.
• The walls of intestine secretes intestinal juices that contains a number of enzymes which completes the digestion of complex carbohydrates into glucose, proteins into amino acids and fats into fatty acids and glycerol