Theory question 102
Animal Nutrition(a) In sequence, name the organs that constitute the alimentary canal of humans. (b) State: (i) three structural differences; (ii) three structural similarities; between the alimentary canal of a bird and human. (c) Explain briefly how the dentition of herbivores is adapted for feeding. (d) State two roles of the pancreas in digestion.
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(a) Mouth (buccal cavity) → pharynx → oesophagus → stomach → small intestine (duodenum, ileum) → large intestine (caecum and appendix, colon) → rectum → anus.
(b)(i) Any three: bird has a beak, human has lips and teeth; bird has no teeth, human has teeth; bird has a crop, human has none; bird has a gizzard, human has none; bird has two caeca, human has one caecum and appendix; bird's gut opens into a cloaca, human's into an anus.
(ii) Any three: both have an oesophagus; both have a stomach (proventriculus in bird); both have a small intestine and large intestine; both have a liver and pancreas; both have a tongue.
(c) Incisors are sharp and chisel-like for cutting grass (upper incisors replaced by a horny pad in cattle); canines are absent or small, leaving a gap (diastema) so the tongue can move food; premolars and molars are broad with ridges for grinding; jaws move sideways for grinding; molars have open roots and keep growing.
(d) Any two: makes pancreatic juice with amylase (starch → maltose), trypsin (protein → peptides) and lipase (fat → fatty acids and glycerol); its alkaline juice (sodium hydrogencarbonate) neutralises acid chyme from the stomach.
In (b), compare the same structure in both animals on each line.