Tag: digestive system - organs

Questions Related to digestive system - organs

Human dental formula of adult is:

  1. $\dfrac{2123}{2123}$

  2. $\dfrac{2123}{1223}$

  3. $\dfrac{1223}{2123}$

  4. $\dfrac{1223}{1223}$


Correct Option: A

Elephant tusks are upper incisors, whereas walrus tusks are

  1. Upper incisors

  2. Lower incisors

  3. Upper canines

  4. Lower canines


Correct Option: C
Explanation:

Walrus tusk ivory comes from two modified upper canines. It is also known as 'morse'. Walrus teeth are also commercially carved and traded. The average walrus tooth has a rounded, irregular peg shape and is approximately 5 cm in length.

Which of the following teeth are absent in a rat?

  1. Canines and molars

  2. Incisors and molars

  3. Incisors and premolars

  4. Canines and premolars


Correct Option: D
Explanation:

Rats have incisors and molars. Incisors are the foremost teeth in mammals. In rats, there are four, long, sharp front teeth, two on top and two on the bottom. They are specialized for gnawing. Molars are rearmost teeth in the mouth of rat used for grinding food prior to swallowing it. Rats have 12 molars, six on top and six on the bottom. Rats do not have canines (the conical, pointed teeth used for holding prey, defense) or premolars (grinding teeth behind the canines and in front of the molars).
Thus, the correct answer is option D.

Premolars are absent in

  1. Rat

  2. Elephant

  3. Both A and B

  4. None of the above


Correct Option: D
Explanation:

Elephants have 26 teeth- 2 incisors (known as tusks), 12 deciduous premolars and 12 molars.
Rats have 8 teeth on the lower jaw and 8 on the upper jaw, a total of sixteen teeth which consists incisor, premolar and molar.
Thus, the correct answer is option D.

In Rabbit and Hare, the incisors of upper and lower jaw halves are

  1. 1 / 1

  2. 2 / 1

  3. 2 / 2

  4. 2 / 0


Correct Option: B
Explanation:

The incisors and cheek teeth of rabbits are called aradicular hypsodont teeth. This is sometimes referred to as an elodent dentition. These teeth grow or erupt continuously. The growth or eruption is held in balance by dental abrasion from chewing a diet high in fibre. The anatomic dental formula is 2( i2/1 c0/0 m3/2 )= 16  deciduous teeth.


So, the correct option is '2/1'.

Dental formula of elephant is

  1. $ \dfrac {1,0,0,3}{0,0,0,3} $

  2. $ \dfrac {1,0,0,3}{1,0,0,3} $

  3. $ \dfrac {1,0,2,3}{1,0,1,3} $

  4. $ \dfrac {2,0,3,3}{1,0,3,3} $


Correct Option: A
Explanation:

The dental formula of adult elephants for both species is I 1/0 C 0/0 PM 3/3 M 3/3, with a total number of 26 teeth. The two upper incisors are the tusks.


So, the correct option is 'Option A'.

Dental formula of adult human is

  1. $\frac{2122}{2122}$

  2. $\frac{2114}{2114}$

  3. $\frac{2123}{2124}$

  4. $\frac{2123}{2123}$


Correct Option: D

Dental formula of a child is

  1. $\frac{2102}{2102}$

  2. $\frac{2120}{2120}$

  3. $\frac{2123}{2123}$

  4. $\frac{2111}{2111}$


Correct Option: A

Dental formula shows

  1. Structure of teeth

  2. Monophyodont or diphyodont condition

  3. Number and type of teeth in both jaws

  4. Number and type of teeth in one half of both jaws


Correct Option: D

Read the following statements and select the correct option.


Statement 1 : Dental formula gives the number of teeth in the half of each jaw.
Statement 2 : Dental formula can be expressed for insectivorous mammals as well as for the non-mammalian vertebrates. 

  1. Both statements 1 and 2 are correct.

  2. Statement 1 is correct but statement 2 is incorrect.

  3. Statement 1 is incorrect but statement 2 is correct.

  4. Both statements 1 and 2 are incorrect.


Correct Option: B