Biology

Respiration and Gas Exchange

989 Questions

Access a targeted set of questions on respiration and gas exchange for competitive exams. Topics include lung volumes, the mechanism of breathing, and respiratory anatomy. Understanding these physiological processes is essential for scoring well.

Lung volumes and capacitiesBreathing mechanismsRespiratory anatomyGas exchange processes

Respiration and Gas Exchange Questions

Multiple choice evs respiration in organism respiration in humans mechanism of respiration in animals human lungs

The diaphragm contracts, resulting in inhalation as the volume of thoracic cavity

  1. Decreases in anteroposterior axis

  2. Decreases in dorsoventral axis

  3. Increases in dorsoventral axis

  4. Increases in anteroposterior axis
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During inhalation, the contraction of the diaphragm and external intercostal muscles increases the volume of the thoracic chamber. Specifically, the contraction of the dome-shaped diaphragm increases the volume along the anteroposterior axis, while rib elevation increases the dorsoventral axis.

Multiple choice evs respiration in organism respiration in humans mechanism of respiration in animals human lungs respiration in human beings respiratory organs in humans

Which of the following changes occur in diaphragm and intercoastal muscles when expiration of air takes place?

  1. External intercostal muscles relax and diaphragm contracts

  2. External intercostal muscles contracts and diaphragm relaxes

  3. External intercostal muscles and diaphragm relaxes

  4. External intercostal muscles and diaphragm contracts
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice evs respiration in organism respiration in humans mechanism of respiration in animals human lungs respiration in human beings respiratory organs in humans

The respiratory centre leading to faster breathing is on account of ________________.

  1. Venous blood entering the respiratory centre

  2. Arterial blood entering respiratory

  3. Venous blood leaving the respiratory centre

  4. Arterial blood leaving the respiratory centre
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The medulla oblongata is the primary respiratory control centre. Its main function is to send signals to the muscles that control respiration to cause breathing to occur. The respiratory control centre increase respiratory rate on the account of decrease in blood pH, as the oxygenated blood through veins enter the system, decrease in $CO _2$ levels, increased respiratory rate.

Multiple choice biology human body respiration in humans mechanism of respiration in animals human lungs

If the lung were punctured, which of the following would happen?

  1. The lung would collapse on the side of the puncture.

  2. Both the lung and the chest wall would collapse on the side of the puncture.

  3. Inspiratory signals from medulla become irregular

  4. Interpleural pressure decrease further
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

If the lung is punctured, the intrapleural space is exposed to atmospheric pressure. This eliminates the negative pressure that keeps the lung inflated, causing the lung to collapse (pneumothorax).

Multiple choice biology human body respiration in humans mechanism of respiration in animals human lungs

Which one of the following statements is incorrect?

  1. The residual air in lungs slightly decreases the efficiency of respiration in mammals

  2. The presence of non-respiratory air sacs, increases the efficiency of respiration in birds

  3. In insects, circulating body fluids serve to distribute oxygen to tissues

  4. The principle of counter current flow facilities efficient respiration in gills of fishes
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Residual air in the lungs is essential to keep the alveoli from collapsing between breaths; it does not decrease the efficiency of respiration but rather maintains structural integrity. The other statements correctly describe respiratory adaptations in birds, insects, and fish.

Multiple choice biology human body respiration in humans mechanism of respiration in animals human lungs

Lungs do not collapse between breaths and some air always remains in the lungs which can never be expelled because.

  1. Pressure in the lungs is higher than the atmospheric pressure

  2. There is negative pressure in the lungs

  3. There is negative intrapleural pressure pulling at the lung walls

  4. There is positive intrapleural pressure
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The lungs remain inflated because the intrapleural pressure is lower than the intrapulmonary pressure (negative pressure), which pulls the lungs outward against the chest wall, preventing collapse.

Multiple choice biology human body respiration in humans mechanism of respiration in animals human lungs

Inspiration occurs when there is a negative pressure in the lungs with respect to atmospheric pressure. This negative pressure is achieved when

  1. intrapulmonary pressure is less than the atmospheric pressure

  2. intrapulmonary pressure is greater than the atmospheric pressure

  3. intrapulmonary pressure is equal to the atmospheric pressure

  4. intrapleural pressure becomes more than the intra-alveolar pressure.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Because of the pressure gradient between the lungs and the atmosphere, the air moves into and out of the lungs. Inspiration occurs if the pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure i.e. there is a negative pressure in the lungs with respect to atmospheric pressure.

Multiple choice biology human body respiration in humans mechanism of respiration in animals human lungs

Choose the correct answer from the alternatives given.
The lung is enclosed in a double layered membrane called

  1. pericardium

  2. pleura

  3. periosteum

  4. perichondrium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The pleura refers to the double-layered membrane that covers the lungs. The space between the two membranes is called the pleural cavity. It is filled with a thin, lubricating liquid called pleural fluid, which acts as a lubricant and allows the pleurae to slide effortlessly against each other by reducing friction during respiratory movements. So, the correct option is 'pleura'.