Biology
Assertion (A): Diaphragm contracts and flattens downwards during inspiration.
Reason (R): Diaphragm relaxes and moves upwards to a dome shape during expiration.
- A is True and R is False.
- A is False and R is True.
- Both A and R are True.
- Both A and R are False.
Answer
Both A and R are True.
Reason — During inspiration, the diaphragm contracts and moves downward, becoming flat. This increases the volume of the thoracic cavity, allowing air to flow into the lungs. During expiration, the diaphragm relaxes and returns to its dome-shaped position. This reduces thoracic volume and pushes air out of the lungs.
Related Questions
Assertion (A): The entrance to the oesophagus is guarded by a flap called epiglottis.
Reason (R): Epiglottis closes the entrance of trachea at the time of swallowing food.
- A is True and R is False.
- A is False and R is True.
- Both A and R are True.
- Both A and R are False.
Assertion (A): Pulmonary artery carries blood from the right ventricle of the heart to lungs.
Reason (R): Right ventricle supplies oxygenated blood to the lungs through the pulmonary vein.
- A is True and R is False.
- A is False and R is True.
- Both A and R are True.
- Both A and R are False.
Assertion (A): Asphyxiation is a condition in which the blood becomes more venous by the accumulation of more carbon monoxide as a result of which the oxygen supply is diminished.
Reason (R): Asphyxiation and hypoxia both are different with respect to the amounts of carbon dioxide and oxygen respectively.
- A is True and R is False.
- A is False and R is True.
- Both A and R are True.
- Both A and R are False.
Name the following :
(a) The energy currency of the cell.
(b) The compound formed by the combination of oxygen and haemoglobin.
(c) The common passage of Oesophagus and Trachea.
(d) The muscles found between the ribs which can change the size of the chest cavity lengthwise.
(e) The compound formed by the combination of haemoglobin and carbon dioxide gas.