Biology

Respiration and Gas Transport

647 Questions

Respiration and gas transport deal with the physiological mechanisms of breathing, including the role of hemoglobin in oxygen transport and the removal of carbon dioxide from the blood. Questions cover both aerobic and anaerobic processes, along with related phenomena like altitude sickness. This human biology topic is a staple in the science sections of competitive tests.

Oxygen and hemoglobin transportAnaerobic respiration effectsCarbon dioxide removalAltitude sickness causesBreathing rate regulation

Respiration and Gas Transport Questions

Multiple choice

Oxyhaemoglobin is dissociated into oxygen and deoxyhaemoglobin due to _______.

  1. excess of O2 pressure in tissues

  2. lack of O2 pressure in tissues

  3. lack of O2 pressure in blood

  4. lack of CO2 pressure in blood
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Oxyhaemoglobin releases oxygen in tissues because tissue cells are constantly consuming oxygen for cellular respiration, creating a low partial pressure environment (low pO2) that favors dissociation. This oxygen delivery mechanism is essential for supplying oxygen to metabolically active tissues.

Multiple choice

Carbonic anhydrous is found in __________.

  1. RBC

  2. WBC

  3. Blood plasma

  4. Blood platelets

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The enzyme is called carbonic anhydrase, not 'carbonic anhydrous'. Carbonic anhydrase is found in red blood cells (RBCs) and catalyzes the conversion of CO2 and water to bicarbonate and protons, essential for CO2 transport.

Multiple choice

Which of the following statements characterises erythropoietin?

  1. Erythropoietin is a protein.

  2. Hypoxia inhibits erythropoietin production.

  3. Most erythropoietin is made in the pancreas in adults.

  4. Erythropoietin decelerates the production of red blood cells.

  5. Erythropoietin increases water reabsorption in the Loop of Henle.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Erythropoietin is a glycoprotein hormone consisting a single polypeptide of 166 amino acids. It binds to receptors on early red blood cell precursors and promotes their progression to form red blood cells.

Multiple choice

In which form is iron present in haemglobin

  1. Ionic

  2. unionic

  3. Fe2+

  4. Fe3+
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Iron in haemoglobin is in the ferrous state (Fe2+), which allows oxygen binding. The Fe3+ (ferric) state found in methemoglobin cannot bind oxygen. The ionic/unionic terminology is not standard; Fe2+ is the correct notation.

Multiple choice

The lymph serves to

  1. transport CO2 to the lungs

  2. transport O2 to the brain

  3. return the interstitial fluid to the blood

  4. return the WBCs and RBCs to the lymph nodes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Lymphatic vessels collect interstitial fluid (fluid that leaks out of blood capillaries into tissue spaces) and return it to the bloodstream via the thoracic duct and right lymphatic duct. Lymph does not transport CO2 or O2 - those functions are performed by blood. Lymph nodes contain lymphocytes, not RBCs.

Multiple choice

RBCs take up glucose through

  1. symport

  2. antiport

  3. facilitated diffusion

  4. active transport

  5. ABC transport
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

RBCs take glucose through facilitated diffusion and not by active transport.

Multiple choice

RBCs take glucose through-

  1. symport.

  2. antiport.

  3. passive transport/facilitated diffusion.

  4. active transport

  5. ABC transport.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

RBCs take glucose through facilitated diffusion and not through active transport.

Multiple choice

Which of the following is/are required for the synthesis of haemoglobin?

  1. Methaemoglobin

  2. Bilirubin

  3. Succinyl CoA and glycine

  4. Oxyhaemoglobin

  5. Biliverdin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

These compounds are synthesised in normoblastic stage of developing red blood cells. Two molecules of succinyl CoA and two molecules of glycine combine to form a pyrolle ring. Four pyrolles combine together to form protoporphyrin IX. Protoporphyrin IX combines with iron and polypeptide chain to form haemoglobin chain. Four such haemoglobin chains make up haemoglobin molecule.

Multiple choice

Which of the following processes slows down in the presence of oxygen?

  1. Nitrogen-fixation in root nodule of legumes

  2. Respiration in human beings

  3. Burning of fossil fuels

  4. Formation of ozone
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Nitrogen fixation in legume root nodules is performed by bacteria like Rhizobium, which require oxygen-free conditions. The enzyme nitrogenase that fixes nitrogen is inhibited by oxygen. Respiration, combustion, and fossil fuel burning all require oxygen to proceed, while ozone formation involves oxygen reactions.

Multiple choice

Heme oxygenase

  1. can oxidize methene bridge between three pyrrole rings of heme

  2. requires molecular oxygen for its activity

  3. produces bilirubin and carbon dioxide

  4. can use protoporphyrin as substrate

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heme oxygenase is the enzyme that catalyzes the first step in heme degradation, which is the oxidation of the methene bridge between the pyrrole rings. This cleavage produces biliverdin, free iron, and carbon monoxide (not carbon dioxide). The enzyme does require molecular oxygen for its activity, but option A describes the core catalytic function more specifically.