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

The correct answer is Diaphragm.

Key Points

• A large, muscular sheet called a diaphragm forms the floor of the chest cavity.
• The diaphragm, located below the lungs, is the major muscle of respiration.
• It is a large, dome-shaped muscle that contracts rhythmically and continually, and most of the time, involuntarily.
• Upon inhalation, the diaphragm contracts and flattens and the chest cavity enlarges.

Additional Information

• Duodenum - The first part of the small intestine. It connects to the stomach. The duodenum helps to further digest food coming from the stomach. It absorbs nutrients (vitamins, minerals, carbohydrates, fats, proteins) and water from food so they can be used by the body.
• The larynx is a hollow tube that connects your throat (pharynx) to the rest of your respiratory system. It helps you swallow safely and contains the vocal cords, so it's often called the voice box. 
• The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out. Oxygen breathed in from the air passes through the alveoli and into the blood and travels to the tissues throughout the body.

The correct answer is Pyruvate

Explanation:

• During intense physical activity, such as rigorous exercise, the oxygen supply to muscle cells may not be sufficient to meet the energy demands of the body.
• This leads to anaerobic respiration in muscle cells, where glucose is partially broken down to generate energy in the form of ATP.
• In the absence of sufficient oxygen, pyruvate (a product of glycolysis) is converted into lactic acid by the enzyme lactate dehydrogenase.
• The accumulation of lactic acid in muscle cells is responsible for muscle cramps and fatigue during prolonged or intense exercise.

Pyruvate is a key intermediate in cellular respiration.

• In the presence of oxygen (aerobic conditions), pyruvate enters the mitochondria and is converted into acetyl-CoA for the citric acid cycle.
• However, under anaerobic conditions, pyruvate is converted into lactic acid in muscle cells to regenerate NAD⁺, which is essential for glycolysis to continue and produce ATP. This process is called lactic acid fermentation.

Other Options:

• ATP: ATP (adenosine triphosphate) is the energy currency of the cell. It is produced during glycolysis, the citric acid cycle, and oxidative phosphorylation. ATP is not directly converted into lactic acid; rather, its production is facilitated by glycolysis, where pyruvate is formed as an intermediate.
• Ethanol: Ethanol is a byproduct of fermentation in certain microorganisms, such as yeast. It is not produced in human muscle cells. Humans undergo lactic acid fermentation, not alcoholic fermentation, under anaerobic conditions.
• Glucose: Glucose is the primary source of energy in cellular respiration. It undergoes glycolysis to produce pyruvate, which can subsequently be converted into lactic acid under anaerobic conditions. 

• 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 Pharynx.

Key Points

• The pharynx is a vital structure in the human respiratory system that serves as a passageway for both air and food.
• It is divided into three parts: the nasopharynx, oropharynx, and laryngopharynx, which play distinct roles in respiration and digestion.
• The pharynx connects the nasal cavity to the larynx and the oral cavity to the esophagus, ensuring proper air and food movement.
• It is lined with mucous membranes that help filter, warm, and moisten the air before it enters the lungs.
• The pharynx also contains tonsils, which are part of the immune system and help protect the body against infections.

Additional Information

• Respiratory System Overview:
  • The respiratory system includes organs such as the nose, pharynx, larynx, trachea, bronchi, and lungs.
  • Its primary function is to facilitate gas exchange, delivering oxygen to the blood and removing carbon dioxide.
  • The system works closely with the circulatory system to transport gases efficiently.
• Nasopharynx:
  • The upper part of the pharynx located behind the nasal cavity.
  • It serves as an airway and contains openings to the auditory tubes, which help equalize pressure in the middle ear.
• Oropharynx:
  • The middle section of the pharynx located behind the oral cavity.
  • It plays a role in both respiration and digestion, allowing air and food to pass.
• Laryngopharynx:
  • The lower section of the pharynx located behind the larynx.
  • It directs air to the larynx and food to the esophagus.
• Terminologies:
  • Aorta: Part of the circulatory system, responsible for carrying oxygen-rich blood from the heart to the body.
  • Urethra: Part of the urinary system, responsible for transporting urine from the bladder to outside the body.
  • Bile duct: Part of the digestive system, responsible for carrying bile from the liver and gallbladder to the small intestine.

The correct answer is Statement II and IV are correct.

Key Points

• Statement II: Respiration is the process of breaking down glucose with the help of oxygen to release energy. This energy is utilized by the body for various functions. It is a chemical process that occurs in the cells, involving the oxidation of glucose to produce ATP (Adenosine Triphosphate).
• Statement IV: During inhalation, the diaphragm moves downward to create more space in the chest cavity, allowing the lungs to expand and fill with air. This movement is crucial for effective breathing.
• Both Statement II and Statement IV are scientifically accurate, as they describe the fundamental aspects of respiration and the mechanics of breathing.
• In contrast, the incorrect statements either misstate the role of organs or confuse different biological processes.

Additional Information

Anaerobic respiration

• Anaerobic respiration is the type of respiration through which cells can break down sugars to generate energy in the absence of oxygen.
• It is an energy yielding process in which the terminal electron acceptor for the electron transport chain is a molecule other than oxygen.
• Anaerobic respiration is not as efficient in ATP synthesis as in that of aerobic respiration.
• The end products of anaerobic respiration are carbon dioxide and ethyl alcohol.
• C6H12O6 → 2C2H5OH + 2CO2 + ATP 

Therefore in anaerobic respiration Carbon dioxide is given out.

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.

• 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.

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.

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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