(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
Explanation
(a) Organs of alimentary canal of humans in sequence
- Mouth/buccal cavity
- Oesophagus/gullet
- Stomach
- Duodenum
- Ileum/jejunum/small intestine
- Caecum/Colon/Large intestine
- Rectum.
(b)(i) Structural differences between the alimentary canal of a bird and human
| Bird | Human |
| Beak present / mouth modified to beak | Beak absent / present of mouth |
| Teeth absent | teeth present |
| Crop present | crop absent |
| Gizzard present | gizzard absent |
| Anal pore modified to cloaca | anal pore modified to anus |
| Shorter alimentary canal | Longer alimentary canal |
| Appendix absent | appendix present |
(ii) Similarities in the alimentary canal of a bird and human;
They both have mouth; oesophagus/gullet; stomach; duodenum; small intestine; large intestine; caecum; rectum.
(c) Adaptation of the dentition of herbivores for feeding
- Elongated/curved incisors; for cutting grass/herbs
- Thick horny pad; against which the lower incisors bit
- Canines are absent/presence of diastema; allows tongue to roll the cropped grass
- Broad surfaces of the cheek teeth/molars; for grinding/chewing/masticating.
- Ridges/furrows on cheek teeth/molars; for grinding/chewing/masticating
(d) Roles of pancreas in digestion
- Produces pancreatic juices which contain enzymes
- Sodium bicarbonate in the pancreatic juice neutralizes the HCL from the stomach/produces alkaline medium
- Pancreatic amylase digests starch to maltose
- Trypsin in the pancreatic juice digests protein to peptides/peptones
- Lipase in the pancreatic juice digests fat droplets to glycerol and fatty acid