Digestive System and Nutrition

• The digestive system breaks down food into nutrients that the body can use.
• Chemical digestion involves enzymes breaking down complex organic compounds into simpler substances through hydrolysis reactions.
• The digestion process is the breakdown of food into smaller molecules that can be absorbed by cells.
• If a reducing sugar is present what colour will Benedict's solution change to?

  Brick-Red
• Which chemical can be used to test for the presence of starch?

  Iodine
• In the diagram of the human digestive system, what organ is labelled 2?

  Stomach

  
• What is mostly absorbed from the food during its passage down the large intestine?

  Water
• Look at the diagram. Name organ 1.

  Stomach

  
• If we become "dehydrated", what substance are we lacking?

  Water
• What is the name of the enzyme that digests carbohydrates?

  Carbohydrase or Amylase
• In which part of the gut is water absorbed from undigested food?

  Large intestine
• Which of these is a good source of fibre?

  -Egg - Milk - Chicken - Banana

  Banana
• Which organ produces bile?

  4 (liver)

  
• True or false? Vegetable oils are part of a balanced diet.

  True
• Deficiency diseases are caused by a lack of vitamins and what else?

  Minerals
• In the diagram of the human digestive system, what organ is labelled 5?

  Large intestine

  
• Meat, fish and eggs are a good source of which food group?

  Protein
• If protein is present what colour will biuret change to?

  Purple
• What is pasta (not wholemeal pasta) a good source of?

  Carbohydrates

  
• What substance found in fats is thought to contribute to heart disease?

  Cholesterol
• Which food group is shown in the picture below?

  Protein

  
• Enzymes are catalysts which increase the rate of a chemical reaction.
• Is fibre needed to help push food through our digestive system?

  Yes
• Look at the diagram. Name organ 2.

  Small intestine

  
• What is thirst a sign of?


  Dehydration
• Look at the diagram. Name organ 4.

  Liver

  
• Teeth break food down into small pieces. Broken up food is mixed with enzymes in your saliva. The enzymes start to break down carbohydrates into sugars.
• The oesophagus is a thin tube connecting the mouth and stomach. Chewed up food is called a bolus - this passes down the oesophagus. Saliva softens the bolus.
• A stomach is about the size of a fist, but can expand to several times this size. It churns to mix food with stomach acid, which kills unwanted bacteria. The food also mixes with enzymes that break down protein into amino acids.
• The liver produces bile and pumps it into the small intestine. It emulsifies large fat molecules and then turns them into smaller droplets. It neutralises the low pH of stomach acid. Food does not pass directly through the liver.
• The pancreas produces three types of enzymes to break down carbohydrate, proteins and fats. These are pumped into the small intestine. Food does not pass directly through the pancreas.
• The small intestine is around 6 meters long. Fats are digested into fatty acids and glycerol, and breakdown of carbohydrates and proteins continues. The intestine is covered with villi which help absorb nutrients quickly.
• The large intestine is wider than the small intestine and about 1.5 meters long. Water is absorbed from digested food, leaving undigestible fibre which is excreted.
• The undigested fibre is stored as faeces in the rectum.
• The anus is the opening at the end of the digestive system. Faeces leaves your body.