Teeth

1. TEETH

2. Different animals have different teeth. Why? Depends on the type of food that they eat 1 2 3 4 5 Human Cow Cat Dog Horse

3. Animals are called: Eat mainly vegetation Eat other animals Eat both vegetation & flesh Herbivores - sheep, rabbit Carnivores - dog, tiger Omnivores - bears, pigs

4. 4 different types of teeth These different teeth have different jobs! incisor canine premolar molar

5. Incisors These are used for cutting & biting off pieces of food Chisel-shaped

6. Cutting by incisors

7. Canines These are long, pointed and sharp teeth that are used to hold and tear at food; kill prey

8. Premolars are used to crush & grind soft food premolars

9. Molars used for chewing & grinding hard food cusps

10. Fig. 1 Dog – a carnivore. Carnassial teeth

11. Carnassial teeth slide past each other in a scissor-like fashion as the mouth is closed are adapted for shearing flesh

12. Fig. 2 Sheep – a herbivore. (blunt)

13. Sheep & Cows have no upper incisors, unlike horses: Horny pad of gum horse sheep

14. Function of the horny pad on upper jaw: t he lower teeth grind against the horny pad to cut grass.

15. Compare canines in herbivores and carnivores Large, long and pointed: to kill prey & hold it Small as in sheep OR absent as in cows: no need to kill sheep cow

16. Diastema is a space where food collects before being pushed back by the tongue

17. Why are premolars & molars very flat in herbivores? Provide a large surface area for crushing grass.

18. Teeth in: Herbivores grow throughout life. Carnivores & omnivores stop growing. Overgrown teeth in a rabbit.

19. Enamel ridges Herbivore Carnivore

20. Human Jaw

21. Tooth Function Incisor To cut Canine To tear flesh; to hold the prey; kill prey Premolar To crush Molar To crush

22. Look at the skull. What type of food did the animal eat? Flesh

23. Plants

24. The lower jaw moves: Up and down Herbivores Carnivores & Omnivores Sideways and back and forth

25. Question: SEP, 2007 The following diagram shows the skull of a lion . a. List TWO characteristics of canines visible in the diagram. (2) Long and pointed. b. i ) What are the canines used for? (1) To hold the prey in place / tear flesh .   ii) What are the carnassials used for? (1) Crush flesh and bones.

26. c. i ) Explain why carnivores have a proportionally large liver. (1) Excess amino acids are deaminated in the liver.   ii) In a carnivore the upper and lower jaw fit together so closely that they cannot be dislocated. Explain the benefit of this. (1) So the jaw does not dislocate as the prey struggles to become free .

27. d . i ) In sheep a horny pad replaces the incisors and canines on the upper jaw. Explain the function of the horny pad. (1) The lower teeth grind against the horny pad to cut grass.   ii) In herbivores such as sheep the upper and lower jaw fit loosely. What is the benefit of this? To allow side to side movement during chewing. (2) iii) Name the TWO types of teeth that herbivores use to grind and chew the vegetation. Molars and premolars . ( 2)

28. Question: MAY, 2010 Give a biological explanation for the following statement: The dentition of a rabbit is adapted to its diet. (5) The front incisors are chisel-shaped and adapted for cutting. The molars and premolars have flat grinding surfaces that continue to grow throughout life as they are worn away by grinding. The upper and lower jaw fit together very loosely to allow side-to-side movement during chewing. Diastema to enable manipulation of food. Rabbit is a herbivore.

29. CELLULOSE DIGESTION IN HERBIVORES

30. Most herbivores have a problem: eat grass: principal component is cellulose cannot produce cellulases Mutualistic bacteria in digestive system produce cellulases . Solution

31. A ruminant has FOUR stomach chambers

32. Fig. 3 A ruminant . e .g. cow, sheep, goat, camel a ruminant has a stomach made of four chambers, the biggest being the rumen

33. Where are the bacteria able to make cellulase found in rabbits & cows? Non ruminants Ruminants Cow Rabbit

34. The rumen contains mutualistic bacteria that produce the enzyme cellulase .

35. A ruminant: Cuts the grass and swallows it into the rumen. Bacteria in rumen make cellulase to digest the cellulose. T he grass is regurgitated and chewed by the flat molars and premolars.

36. Chewing the cud is when the grass is regurgitated and chewed by the flat molars and premolars A cow makes between 40,000-60,000 jaw movements a day chewing What’s up…I’m chewing my cud…Sometimes I chew over 100 times before swallowing!

37. The length of the vertebrate digestive system is related with diet . Explain why, in general herbivores & omnivores have longer alimentary canals relative to their body sizes than carnivores.

38. A longer alimentary canal provides more: 1. time for digestion 2. surface area for absorption of nutrients . Vegetation is more difficult to digest than meat because it contains cells walls.

39. Question: MAY, 2012 The table below lists a number of characteristics related to the dentition of dogs and a sheep. For each statement in the tablemark the box with a tick (  ) if correct and a cross (  ) if incorrect. (4) STATEMENT DOGS SHEEP Incisors found on both upper and lower jaws. Molars wear down to form enamel ridges. Strong jaw muscles that allow extensive chewing of food. Jaw joint only allows up and down movement.

40. STATEMENT DOGS SHEEP Incisors found on both upper and lower jaws.   Molars wear down to form enamel ridges.   Strong jaw muscles that allow extensive chewing of food.   Jaw joint only allows up and down movement.  

41. Question: SEP, 2008 Give a biological explanation for each of the following statements: Sheep have cellulose-digesting bacteria in their gut but lions do not. (4) Sheep are herbivores and eat grass with a high cellulose content. Bacteria produce cellulase to digest cellulose. Lions are carnivores and do not need the bacteria.

42. THE END Make sure you do not END up in a shark’s jaws!!