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 biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

Respiratory quotient (R.Q.) is

  1. Volume of O$ _2$ evolved / Volume of CO$ _2$ consumed
  2. Volume of CO$ _2$ evolved / Volume of O$ _2$ consumed
  3. Volume of O$ _2$ consumed / Volume of CO$ _2$ evolved
  4. Volume of CO$ _2$ consumed / Volume of O$ _2$ evolved
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Respiratory quotient or R.Q. is the ratio of volume of CO$ _2$ produced to volume of O$ _2$ consumed during cellular respiration. It is measured by Ganong's Respirometer. R.Q. for carbohydrates is 1, organic acid is >1 and fats and proteins is <1.

So, the correct answer is 'Volume of CO$ _2$ evolved / Volume of O$ _2$ consumed'.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

Identify the sequence of steps involved during inspiration in rabbit.
(A) Volume of thoracic cavity increases
(B) Contraction of external intercostal muscles moves the rib cage forward
(C) Diaphragm becomes flat
(D) Thoracic cavity expands drawing air into lungs.

  1. (C)$\rightarrow$(B)$\rightarrow$ (A)$\rightarrow$(D)
  2. (C)$\rightarrow$(A)$\rightarrow$ (B)$\rightarrow$ (D)
  3. (A)$\rightarrow$(B)$\rightarrow $(C)$\rightarrow$ (D)
  4. (A)$\rightarrow$(D)$\rightarrow$ (B) $\rightarrow$ (C)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The urge to breathe comes from the respiratory center, located at the base of brain. It sends signals via the spinal cord to diaphragm and the muscles between ribs telling them when to contract or relax. During inspiration, the diaphragm -- the large muscle that divides chest and abdomen -- contracts and moves downward. Additionally, ribs move outward. This enlarges your chest and lungs expand. Lung expansion creates a vacuum. Air enters the nose and mouth and is pulled into windpipe -- the trachea. The trachea divides into smaller airways called bronchi. These continue to divide as they get farther from the trachea, like the branches of a tree. Finally, the tiny airways deliver the air to the smallest structures in your lung -- the alveoli -- where gas exchange takes place.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

Respiratory quotient may be represented as

  1. ${O} _{2}$ taken in/${CO} _{2}$ evolved
  2. ${CO} _{2}$ evolved/${O} _{2}$ taken in
  3. ${O} _{2}$ taken in
  4. ${CO} _{2}$ taken in
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During aerobic respiration, ${O} _{2}$ is consumed and ${CO} _{2}$ is released. The ratio of the volume of ${CO} _{2}$ evolved to the volume of ${O} _{2}$ consumed in respiration over a period of time is called as respiratory quotient (RQ) or respiratory ratio.
$RQ=\frac{Volume\,\, of\,\, {CO} _{2} \,\,evolved}{Volume \,\,of \,\,{O} _{2} \,\,consumed}$.

So the correct option is B.

Multiple choice biology respiration and energy transfer respiratory quotient-basic respiration-plants respiratory quotient

Respiratory quotient is defined as

  1. $O _2$ evolved / $CO _2$ absorbed
  2. $CO _2$ evolved / $O _2$ absorbed
  3. $CO _2$ evolved
  4. $CO _2$ absorbed/ $O _2$ evolved.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The respiratory quotient can be defined as the ratio of the CO2 evolved to the O2 absorbed this could be calculated for a cell, a tissue, or even an organism.
So, the correct answer is 'CO2 evolved / O2 absorbed'.
Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

The respiratory centers, which control inspiration and expiration, are located in?

  1. Diencephalon

  2. Medulla oblongata

  3. Cerebellum

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

The primary respiratory rhythm center and the pneumotaxic center, which control the rate and depth of breathing, are located in the brainstem. Specifically, the medulla oblongata houses the main inspiratory and expiratory centers, making option B correct.

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Air is breathed through

  1. Trachea $\rightarrow$ lungs $\rightarrow$ larynx $\rightarrow$ pharynx $\rightarrow$ alveoli
  2. Nose $\rightarrow$ larynx $\rightarrow$ pharynx $\rightarrow$ bronchus $\rightarrow$ alveoli $\rightarrow$ bronchioles
  3. Nostril $\rightarrow$ pharynx $\rightarrow$ larynx $\rightarrow$ trachea $\rightarrow$ bronchi $\rightarrow$ bronchioles $\rightarrow$ alveoli
  4. Nose $\rightarrow$ mouth $\rightarrow$ lungs
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In humans respiratory system consists of respiratory tract (conducting zone) and lungs (exchange zone). The respiratory tract is the passage from external nostrils to lungs or a passage by which air enters into lungs. The respiratory passage starting from external nostrils is nasal chamber --> internal nares --> nasopharynx -->pharynx --> glottis --> larynx --> trachea --> bronchial tree (bronchi and bronchioles) --> alveoli.

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

In fever breathing rate

  1. Increase

  2. Decrease

  3. Stop

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Normal body temperature is around $37^0$C. Fever happens when the body's temperature is higher than normal because of an infection. Fever causes an increase in the heart rate, breathing rate and blood circulation to the skin. This is how the body tries to reduce the heat caused by fever. 

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Which energy is consumed in breathing?

  1. Mechanical

  2. Chemical

  3. Bioelectricity

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

In breathing or cellular respiration, a set of metabolic reactions and processes take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, releasing energy. Respiration is one of the key ways a cell gains useful energy to fuel cellular activity. Cellular respiration is considered an exothermic redox reaction which releases heat. The overall reaction occurs in a series of biochemical steps, most of which are redox reactions themselves.

Therefore, the correct answer is option B.

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Breathing by ribs is more pronounced in

  1. Male

  2. Female

  3. Pregnant female

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During the third trimester, as the uterus continues to grow, it puts pressure on the internal organs and the diaphragm, which in turns restricts the amount of room available for lungs and leads to shortness of breath. So breathing by ribs is more pronounced during pregnancy, as it slightly raises the rib cage and temporarily gives more breathing space to lungs making breathing little easier.

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Cutaneous respiration takes place through

  1. Gills

  2. Lungs

  3. Skin

  4. Cell membrane
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cutaneous respiration or cutaneous gas exchange, is a form of respiration in which gas exchange occurs across the skin or outer integument of an organism rather than gills or lungs. Cutaneous respiration may be the sole method of gas exchange, or may accompany other forms, such as ventilation. Cutaneous respiration occurs in a wide variety of organisms, including insects, amphibians, fish, sea snakes, turtles, and to a lesser extent in mammals, including humans. 

Therefore, the correct answer is option C.

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Which of the following features do all gas exchange have in common?

  1. They are enclosed within ribs.

  2. They are maintained at constant temperature.

  3. The exchange surfaces are moist.

  4. They are exposed to air.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gas exchange and respiration are essential if cells are to stay active, grow and divide. All the structures for gas exchange have common as follows:

  • They have a large surface area relative to the volume of the organism. 
  • They are thin and so have a short diffusion pathway. 
  • They have a moist surface where gases can dissolve first before they diffuse in or out. 
  • They are able to maintain the diffusion gradient down which the gases can diffuse.
Therefore, the correct answer is option C.

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Ribs move out in during

  1. Inhalation

  2. Exhalation

  3. Coughing

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

  • Relaxation of the diaphragm and the inter-costal muscles returns the diaphragm and sternum and ribs move into their normal positions and reduce the thoracic volume and thereby the pulmonary volume. 
  • This leads to an increase in intra-pulmonary pressure to slightly above the atmospheric pressure causing the expulsion of air from the lungs, i.e., expiration. Hence, ribs move out in during exhalation.
So, the correct answer is 'exhalation'.

Multiple choice zoology respiratory system phases in respiration human respiratory system parts of respiration

Respiratory membrane consists of.

  1. Alveolar wall and ducts

  2. Membrane of alveolar ducts and capillaries

  3. Inner and outer pleural membranes and pleural fluid

  4. Alveolar wall, alveolar capillary and interstitial space
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The respiratory membrane (alveolar-capillary membrane) consists of the alveolar epithelial wall, the capillary endothelial wall, and the fused basement membrane (interstitial space) between them.