Theory question 101
Animal Nutrition(a) Make a labelled diagram of the vertical section of the mammalian tooth
(b) Describe the role of the following in mammalian nutrition: (i) teeth; (ii) tongue; (iii) saliva; (iv) stomach.
(c) Describe how to test for protein in a food sample
Show the model answer
(a) Labels: crown, neck (gum line), root; enamel, dentine, pulp cavity with blood vessels and nerves, cement, gum, periodontal fibres, jaw bone, root canal
(b)(i) Teeth: bite, tear and grind food into small pieces, increasing surface area for enzymes
(ii) Tongue: tastes food; mixes it with saliva; rolls it into a bolus and pushes it back for swallowing
(iii) Saliva: moistens and lubricates food; salivary amylase (ptyalin) begins digestion of starch to maltose; dissolves food for tasting
(iv) Stomach: stores food; churns it by muscular contraction; gastric juice – HCl gives acid medium and kills bacteria; pepsin digests protein to peptides; rennin curdles milk
(c) Biuret test: add sodium hydroxide solution to the food solution, then a few drops of dilute copper sulphate and shake – a violet/purple colour shows protein; or Millon's test: add Millon's reagent and heat gently – a red/pink precipitate shows protein
For the food test, state reagents, method and the positive result.