Respiratory System MCQ Quiz - Objective Question with Answer for Respiratory System - Download Free PDF

• The Left atrium of the human heart receives abundant oxygen-rich blood from the lungs.
• The pulmonary veins channels oxygen-rich blood to the left atrium.
• The inferior and superior vena cava brings the oxygen-poor blood from the body into the right atrium.
• The pulmonary artery brings oxygen-poor blood from the right ventricle into the lungs.

The Correct answer is Alveoli, exhalation.

Key Points

• In the process of respiration, oxygen is absorbed in the alveoli, which are microscopic air sacs located in the lungs.
• Each alveolus is surrounded by a network of capillaries, where the exchange of gases takes place.
• Oxygen diffuses from the alveoli into the blood through the thin walls of the capillaries.
• The oxygen binds to hemoglobin in red blood cells and is transported to various parts of the body.
• Carbon dioxide, a waste product of cellular respiration, is transported back to the lungs via the blood.
• It diffuses from the blood into the alveoli and is expelled from the body during the process of exhalation.
• Thus, the alveoli play a crucial role in the process of gas exchange, ensuring that oxygen enters the bloodstream and carbon dioxide is removed.
• The rhythmic process of inhalation and exhalation ensures a continuous supply of oxygen and removal of carbon dioxide, maintaining the body's homeostasis.

Additional Information

• Alveoli
  • Alveoli are tiny, balloon-like structures located at the end of the bronchioles in the lungs.
  • They are the primary site of gas exchange in the respiratory system.
  • Alveoli are highly specialized for this function due to their thin walls and their extensive network of capillaries.
  • Humans have approximately 300–500 million alveoli, providing a large surface area for efficient gas exchange.
• Bronchi
  • The bronchi are the major air passages that branch off from the trachea and lead to each lung.
  • They further divide into smaller branches called bronchioles, which eventually end in the alveoli.
  • The bronchi are primarily responsible for conducting air to and from the alveoli but are not involved in the actual exchange of gases.
• Inhalation and Exhalation
  • Inhalation is the process of taking air into the lungs, driven by the contraction of the diaphragm and intercostal muscles.
  • Exhalation is the process of expelling air from the lungs, primarily a passive process when the muscles relax, though it can be active during forceful breathing.
  • These processes are part of the respiratory cycle, which ensures the continuous exchange of oxygen and carbon dioxide.

Key Points

The Calvin cycle

• The Calvin cycle is a part of photosynthesis, the process plants and other autotrophs use to create nutrients from sunlight and carbon dioxide.
• The process was first identified by American biochemist Dr. Melvin Calvin in 1957.
• Hence Calvin cycle is not involved in Respiratory Process.

Additional Information 

The citric acid cycle

• The citric acid cycle is the key metabolic pathway responsible for the oxidative degradation of amino acids, fatty acids, and carbohydrates and a source of numerous biosynthetic intermediates.
• The tricarboxylic acid (TCA) cycle, also known as the Krebs or citric acid cycle, is the main source of energy for cells and an important part of aerobic respiration.

Glycolysis

• Glycolysis can be broadly defined as an energy-yielding pathway that results in the cleavage of a hexose (glucose) to a triose (pyruvate). Glycolysis is one of the main processes involved in cellular respiration.
• Glycolysis is the pathway that converts sugar into energy, or glucose (C6H12O6) into pyruvate (CH3COCOO), generating ATP during the conversion.

Electron transport chain

• The electron transport chain (ETC) passes electrons from lower to higher standard reduction potentials and ultimately to oxygen-forming water.
• It occurs in both cellular respiration and photosynthesis in the mitochondria.

The correct answer is In mitochondria, one molecule of pyruvate breaks down to give three molecules of carbon dioxide.

Key Points

• Aerobic respiration is a metabolic process that takes place in the presence of oxygen.
• It is the primary method by which cells convert glucose (a type of sugar) into ATP (adenosine triphosphate), the energy currency of the cell.
• It is more efficient than anaerobic respiration and results in the complete oxidation of glucose.
• aerobic respiration consists of four main stages: ​

The correct answer is To increase the surface area.

Key Points

• Alveoli are an important part of the respiratory system whose function it is to exchange oxygen and carbon dioxide molecules to and from the bloodstream.
  • These tiny, balloon-shaped air sacs sit at the very end of the respiratory tree and are arranged in clusters throughout the lungs.
  • The respiratory system is the network of organs and tissues that help you breathe.
  • It includes your airways, lungs, and blood vessels. The muscles that power your lungs are also part of the respiratory system.
  • These parts work together to move oxygen throughout the body and clean out waste gases like carbon dioxide.

Additional Information

• The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion.
  • Digestion involves the breakdown of food into smaller and smaller components until they can be absorbed and assimilated into the body.
• The circulatory system also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body to provide nourishment and help in fighting diseases, stabilize temperature and pH, and maintain homeostasis.
• The nervous system is the part of an animal's body that coordinates its behavior and transmits signals between different body areas.
  • Invertebrates consist of two main parts, called the central nervous system (CNS) and the peripheral nervous system (PNS).
  • The CNS contains the brain and spinal cord.

The correct answer is Whale.

Key Points

• Gills are respiratory organs found in most aquatic organisms.
• Gills can extract dissolved oxygen from water and excrete carbon dioxide.
• Gills can be found in Octopus, Squid, Clownfish, Tadpole, Prawn, etc.
• Lungs are the breathing organ of Whales.

Additional InformationRespiratory organs of different Animals:

The correct answer is Alveoli.

Key Points

• The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.
  • These are tiny air sacs at the end of the bronchioles (tiny branches of air tubes in the lungs).
  • Oxygen breathed in from the air passes through the alveoli and into the blood and travels to the tissues throughout the body.
  • Carbon dioxide travels in the blood from the body's tissues and passes through the alveoli to be breathed out.

The correct answer is Respiration in the presence of oxygen.

Key Points

• The respiration that takes place in the presence of oxygen is termed aerobic respiration.
• The amount of energy released is more in aerobic respiration is quite large in comparison to anaerobic respiration.
• 1 molecule of Glucose in aerobic respiration results in the gain of 36 or 38 molecules of ATP (adenosine triphosphate) in comparison to anaerobic respiration where the gain is of only 2 ATP molecules.
• Aerobic respiration occurs in mitochondria, which is termed as the Powerhouse of the cell.
• Aerobic respiration takes place in higher organisms that have higher energy requirements.

The correct option is 4 i.e., respiration

• During the respiration process, heat energy is formed.
• The process of releasing energy from glucose is called respiration. The energy in glucose can be released in a single reaction. When this happens heat energy is released as glucose burns

There are two main types of respiration

• Aerobic
• Anaerobic

Difference between Aerobic and Anaerobic:

The correct answer is ​CO2 + H2O.

Explanation:

• Aerobic respiration is the process of cellular respiration to produce energy from food in the presence of oxygen.
• This respiration is common in most plants and animals, humans, other mammals, and birds.
• The chemical equation of aerobic respiration is following
  • C6H12O6 + 6O2 →  6CO2 + 6 H2O + Energy
• Hence according to the equation, this respiration's last product is CO2 and H2O.

Additional Information

There are two types of respiration

• Aerobic Respiration- In the Presence of oxygen.
• Anaerobic respiration- In absence of oxygen.
  • Equation of anaerobic respiration
    • C6H12O6 → 2C2H5O H + 2CO2 + Energy 

Important Points

Respiration is of 2 types:

The correct answer is option 1 i.e Inhalation.

Important Points

• Breathing is the process of transfer of air into and out of the lungs to perform gas exchange.
• The breathing cycle consists of two processes namely inhalation and exhalation.
• The process of taking oxygen-rich air in the body is called inhalation.
• The process of giving out carbon dioxide-rich air is known as exhalation.
• Carbon dioxide is a waste product of cellular respiration during the production of energy.
• Both inhalation and exhalation are autonomic processes.
• The average respiration rates for an adult person at rest range from 12 to 20 breaths per minute.
• The average respiration rates for a newborn baby range from 30 to 40 breaths per minute.

The correct answer isCarbon dioxide, water, energy.

• In aerobic respiration, glucose breaks down into Carbon dioxide, water, energy.

Key Points

• Aerobic Respiration:
  • The respiration which takes place in the presence of oxygen is known as aerobic respiration.
  • In this process, in fact, each glucose molecule is converted into two molecules of pyruvic acid by the process, called glycolysis.
  • Glycolysis takes place in the cytoplasm of the cell.
  • The pyruvic acid formed, releases energy with the formation of carbon dioxide and water.
  • C₆H₁₂O₆+ 6O₂→ 6CO₂+ 6H₂O + energy

Additional Information

• Anaerobic Respiration
  • The respiration which takes place in the absence of oxygen is known as anaerobic respiration.
  • In this process, the respiratory substances are incompletely oxidized to carbon dioxide and alcohol.

Key Points

• Lungs are the vascularised bags that are used by the terrestrial forms for the exchange of gases (pulmonary respiration).
• Humans have a pair of lungs that are covered by a double-layered pleura or pleural membrane, with pleural fluid between them.
• It reduces friction on the lung surface.
• The outer pleural membrane is in close contact with the thoracic lining whereas the inner pleural membrane is in contact with the lung surface.

​

Additional Information

• Pericardium - The heart is protected by a double-walled membranous bag, pericardium, enclosing the pericardial fluid. 
• The peritoneum - is the membrane that lines the visceral cavity and enclosed the visceral organs.
• Perichondrium - is a layer of connective tissues that enclose or surrounds the cartilage of a developing bone.

The correct answer is option 3, i.e Pleura.

• Pleura is the membrane that will cover the lungs, it is a double-layered membrane between the double layer membrane and a jelly-like fluid is also present to lower the friction on the long surface.  
• Diaphragm: It is located below the lungs. It is the major muscle of the respiration system, It is a dome-shaped muscle that contracts and expands rhythmically and involuntarily. Upon inhalation, the diaphragm contracts and flattens and the chest cavity enlarges.

Additional Information

• The Left atrium of the human heart receives abundant oxygen-rich blood from the lungs.
• The pulmonary veins channels oxygen-rich blood to the left atrium.
• The inferior and superior vena cava brings the oxygen-poor blood from the body into the right atrium.
• The pulmonary artery brings oxygen-poor blood from the right ventricle into the lungs.