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Difficulty: HardAnimal Nutrition and Digestive System

An adult herbivorous mammal, such as a sheep, has a dental formula represented as i03,c01,pm33,m33i \frac{0}{3}, c \frac{0}{1}, pm \frac{3}{3}, m \frac{3}{3}. What is the total number of teeth present in the animal's mouth, and how does the structural modification of its upper jaw assist in feeding?

  1. 32 teeth; a fibrous horny pad on the upper jaw works against the lower incisors to crop and clip grass.Answer
  2. B
    16 teeth; the upper horny pad secretes extracellular enzymes directly onto unchewed vegetation to initiate digestion.
  3. C
    32 teeth; the upper jaw gap thermally denatures plant proteins during mastication to increase enzyme binding.
  4. D
    20 teeth; missing upper incisors allow enlarged canines to crush tough plant stems and woody fibers.

Answer

32 teeth; a fibrous horny pad on the upper jaw works against the lower incisors to crop and clip grass.
The dental formula i03,c01,pm33,m33i \frac{0}{3}, c \frac{0}{1}, pm \frac{3}{3}, m \frac{3}{3} represents one quadrant pair (half of the upper and lower jaws). Summing the upper teeth (0+0+3+3=60+0+3+3=6) and lower teeth (3+1+3+3=103+1+3+3=10) gives 16 teeth per side. Multiplying by 2 yields a total of 32 teeth. In herbivorous ruminants like sheep, upper incisors are absent and replaced by a tough dental pad that works against the lower incisors to pull and crop vegetation.

Step-by-Step Solution

1
Calculate the number of teeth on one side of the upper jaw.
Upper half-jaw = 0 incisors + 0 canines + 3 premolars + 3 molars = 6 teeth.
The top numbers in the dental formula indicate the teeth present in one half of the upper jaw.
2
Calculate the number of teeth on one side of the lower jaw.
Lower half-jaw = 3 incisors + 1 canine + 3 premolars + 3 molars = 10 teeth.
The bottom numbers in the dental formula indicate the teeth present in one half of the lower jaw.
3
Sum the upper and lower teeth for one side and multiply by 2 for the full mouth.
(6 + 10) × 2 = 16 × 2 = 32 total teeth.
Dental formulas represent only one half of the symmetrical skull, requiring multiplication by two to determine total dentition.
4
Analyze the functional adaptation of the upper jaw in ruminant herbivores.
Upper incisors and canines are absent and replaced by a firm, calloused dental (horny) pad.
During grazing, grass is held between the lower incisors and the horny pad and sheared off with a upward jerk of the head.

Key Concept

Mammalian dental formulas and specialized herbivore feeding adaptations
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Topics

Animal Nutrition and Digestive System

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