Which of the following is not a part of the respiratory system ?

1. Nostrils
2. Lungs
3. Mouth
4. Trachea

The basic structural and functional unit of the lungs is :

1. Pleura
2. Alveolus
3. Capillary
4. Diaphragm

The muscular sheet which divides the body cavity into thorax and abdomen is termed as :

1. Inner pleura
2. Rib cage
3. Outer pleura
4. Diaphragm

Vocal cords are found in :

1. Larynx
2. Gullet
3. Pharynx
4. Glottis