Question

Study the following passage:
Most of the vertebrates have jaws with teeth. The mode of arrangement of teeth on the jaws is called dentition.
The various types of teeth seen in mammals are incisors (I) canines (C) premolars (P) and molars (M). They are used for biting, tearing, chewing and grinding, respectively.
Canines, the tearing teeth are well-developed in carnivores and ill-developed or absent in herbivores.

Now answer the following:
(i) In frogs, all the teeth in the upper jaw look-alike, whereas in human beings they are different. The type of dentition in human beings can be called .........
(a) Homodont (b) Isodont (c) Heterodont (d) Acrodont
(ii) The dental formula of a mammal is written as ICPM=2023/1023. The teeth missing in it are ................
(a) Incisors (b) Canines (c) Premolars (d) Molars

Answer 1

($1$)Homodont dentition is the type of dentition in which all the teeth in the jaw look alike. It is mostly seen in the majority of vertebrates such as fish, amphibians like frogs and reptiles. In them, all the teeth are functionally and anatomically of the same type. While in mammals like human beings, there are functionally four different types of teeth namely, flat incisors for cutting, long and pointed canines for tearing flesh and large and broad premolars and molars with flat and grinding surfaces. Molars have no counterpart in milk teeth. This type of dentition is known as heterodont dentition.

So, option (c) is correct.

($2$)The dental formula for a mammal is given as ICPM=$\frac{2023}{1023}$. The numerator in the formula indicates the number of teeth on one side of the upper jaw, while the denominator indicates the number of teeth on one side of the lower jaw. The formula indicates that there are $2$ incisors, $0$ canines, $2$ premolars and $3$ molars in one side of the upper jaw and $1$ incisor, $0$ canine, $2$ premolars and $3$ molars in one side of the lower jaw.

So, option (b) is correct.