[Campbell Biology P.960] Based on Figure 41.15 and the accompanying text, which of the follo... | Practice Question

Based on Figure 41.15 and the accompanying text, which of the following statements about dental adaptations are TRUE? Select all that apply

  • A: Carnivores possess large, pointed incisors and canines, which are primarily used for killing prey and tearing flesh.
  • B: Herbivores typically have broad, ridged premolars and molars optimized for grinding tough plant material.
  • C: Human adults, as omnivores, are equipped with 32 teeth, including four bladelike incisors, a pair of pointed canines, four premolars, and six molars on each side of the mouth.
  • D: Some herbivores lack incisors entirely, relying solely on their canines and molars for biting vegetation.

Explanation

According to the text accompanying Figure 41.15: A: Carnivores' incisors and canines are described as large and pointed for killing prey and tearing flesh, and their premolars/molars are jagged for crushing/shredding. This statement is accurate. B: Herbivores' premolars and molars are described as broad with ridged surfaces for grinding tough plant material. This statement is accurate. C: Humans, as omnivores, are stated to have 32 teeth, with specific descriptions for incisors bladelike for biting , canines pointed for tearing , premolars for grinding , and molars for crushing , including the numbers given for each type. The description of 'four bladelike incisors, a pair of pointed canines, four premolars, and six molars on each side of the mouth' is not entirely accurate for human dental formula, as humans have 8 incisors total 4 on each jaw, upper/lower , 4 canines 2 on each jaw , 8 premolars 4 on each jaw , and 12 molars 6 on each jaw . The text describes 'four bladelike incisors for biting, a pair of pointed canines for tearing, four premolars for grinding, and six molars for crushing' for the entire mouth , not per side. However, the phrasing 'From front to back along either side of the mouth are...' followed by the numbers might imply per side. Let's re-evaluate. 'Adults have 32 teeth. From front to back along either side of the mouth are four bladelike incisors for biting, a pair of pointed canines for tearing, four premolars for grinding, and six molars for crushing'. This reads as the total count along 'either side of the mouth' for the teeth that go front to back. A human mouth has an upper and lower arcade, each divided into two sides left/right . So, one side e.g., upper left would have 2 incisors, 1 canine, 2 premolars, 3 molars. The description in the text of 4 incisors, 2 canines, 4 premolars, and 6 molars is the total count for one jaw e.g., all upper teeth, or all lower teeth if you sum left and right. If it literally means 'along either side of the mouth' referring to the entire length from front to back on one side of the dental arch e.g., upper left + upper right OR lower left + lower right , this phrasing is highly ambiguous. Let's assume it means the total count for the mouth which is 32 , and that the description is a general count for the human dentition. It's the most plausible interpretation given 'Adults have 32 teeth' followed by this breakdown for all teeth. So, A, B, and C are correct, D is incorrect. Specifically, the text says 'a pair of pointed canines' 2 total , 'four premolars' 4 total , and 'six molars' 6 total in addition to 'four bladelike incisors' 4 total for humans. This sums to 16 teeth. This must be the count for one half of the mouth upper or lower, total of left+right sides combined in that half if the total is 32. This is very confusingly written in the source. Let's re-read: