Respiratory Adaptations Practice Questions
20 free Respiratory Adaptations practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
At high altitudes, the primary respiratory challenge faced by humans is:
- A Increased carbon dioxide concentration in the surrounding air
- B Low atmospheric oxygen partial pressure
- C High air density making breathing more effortful
- D Excess moisture content reducing air quality
Correct answer: Low atmospheric oxygen partial pressure
At high altitudes, the partial pressure of oxygen is low, reducing oxygen diffusion into blood. This leads to hypoxia unless adaptive mechanisms compensate.
One immediate physiological response to high altitude exposure is:
- A Decreased breathing rate
- B Increased breathing rate
- C Reduced heart rate
- D Decreased hemoglobin concentration
Correct answer: Increased breathing rate
The body increases breathing rate to enhance oxygen intake. This helps compensate for reduced oxygen availability in the atmosphere.
Which blood adaptation helps people living at high altitudes transport more oxygen?
- A Lower red blood cell count
- B Higher hemoglobin concentration
- C Reduced blood viscosity
- D Decreased erythropoietin secretion
Correct answer: Higher hemoglobin concentration
High-altitude residents have increased hemoglobin levels, improving oxygen-carrying capacity. This adaptation enhances oxygen delivery to tissues.
Erythropoietin secretion increases at high altitude primarily to:
- A Reduce the body's overall demand for oxygen
- B Stimulate red blood cell production
- C Increase total lung volume and capacity
- D Lower breathing rate to conserve energy at altitude
Correct answer: Stimulate red blood cell production
Low oxygen levels stimulate erythropoietin release from kidneys. This hormone increases red blood cell production to improve oxygen transport.
Which respiratory adaptation is commonly seen in native high-altitude mammals?
- A Comparatively smaller lung size to reduce weight
- B Substantially reduced alveolar surface area for gas exchange
- C Higher lung ventilation efficiency
- D Lower capillary density in lung tissue
Correct answer: Higher lung ventilation efficiency
High-altitude mammals have more efficient lung ventilation. This allows better oxygen uptake under hypoxic conditions.
Underwater respiration in fishes primarily occurs through:
- A Skin
- B Tracheae
- C Gills
- D Lungs
Correct answer: Gills
Gills are specialized respiratory organs in fishes. They allow efficient extraction of dissolved oxygen from water.
Which structural feature of gills increases efficiency of oxygen exchange?
- A Thick epithelial lining for structural protection
- B Reduced surface area to minimize water loss
- C Presence of gill lamellae
- D Air-filled cavities that store oxygen reserves
Correct answer: Presence of gill lamellae
Gill lamellae provide a large surface area for gas exchange. This maximizes oxygen absorption from water.
Counter-current flow in fish gills refers to:
- A Blood and water flowing in the same direction
- B Blood and water flowing in opposite directions
- C Blood flowing faster than water
- D Intermittent flow of water over gills
Correct answer: Blood and water flowing in opposite directions
In counter-current flow, blood flows opposite to water direction. This maintains a diffusion gradient for efficient oxygen uptake.
Why is oxygen extraction more difficult underwater than in air?
- A Oxygen diffuses faster in water than in air
- B Water contains less dissolved oxygen
- C Water temperatures are consistently warmer than air
- D Oxygen is chemically bonded within water molecules
Correct answer: Water contains less dissolved oxygen
Water contains much less dissolved oxygen compared to air. This makes oxygen extraction more challenging for aquatic organisms.
Which adaptation allows aquatic mammals like whales to remain submerged for long durations?
- A Higher lung volume relative to overall body size
- B Increased myoglobin concentration in muscles
- C Lower oxygen-carrying capacity of the blood
- D Permanently reduced metabolic rate at rest and activity
Correct answer: Increased myoglobin concentration in muscles
High myoglobin levels store oxygen in muscles. This supports aerobic respiration during prolonged dives.
In underwater diving mammals, oxygen conservation is aided by:
- A Increased heart rate
- B Peripheral vasoconstriction
- C Continuous lung ventilation
- D Increased sweating
Correct answer: Peripheral vasoconstriction
Peripheral vasoconstriction reduces blood flow to non-essential tissues. This conserves oxygen for vital organs like brain and heart.
Which factor primarily triggers altitude sickness in humans?
- A Extreme low temperature conditions
- B High levels of ultraviolet radiation exposure
- C Reduced oxygen availability
- D Increased atmospheric air pressure at altitude
Correct answer: Reduced oxygen availability
Altitude sickness occurs due to hypoxia caused by reduced oxygen availability. The body initially struggles to adapt to this condition.
Fish ventilate their gills mainly by:
- A Passive diffusion across gills without muscular effort
- B Buccal pumping and opercular movement
- C Diaphragmatic contraction similar to tetrapod breathing
- D Ciliary action along the gill epithelial surface
Correct answer: Buccal pumping and opercular movement
Fish use buccal and opercular movements to pump water over gills. This ensures continuous oxygen supply.
Which adaptation improves oxygen diffusion in high-altitude lungs?
- A Thicker alveolar walls
- B Reduced capillary network
- C Increased capillary density
- D Lower surface area of alveoli
Correct answer: Increased capillary density
Increased capillary density enhances oxygen diffusion into blood. This compensates for low oxygen pressure at high altitudes.
Amphibians respire underwater mainly through:
- A Gills throughout life
- B Lungs only
- C Moist skin
- D Tracheal system
Correct answer: Moist skin
Amphibians use cutaneous respiration through moist skin underwater. This allows diffusion of gases directly with water.
Which adaptation reduces oxygen demand during deep diving in seals?
- A Increasing metabolic rate to burn fuel more efficiently
- B Selective suppression of non-essential organ activity
- C Increasing lung ventilation rate during the dive
- D Raising blood temperature to accelerate circulation
Correct answer: Selective suppression of non-essential organ activity
Seals suppress activity in non-essential organs to reduce oxygen consumption. This adaptation allows longer dives.
Why are gills inefficient for respiration on land?
- A They have a low overall surface area for gas exchange
- B They collapse without water support
- C They completely lack an internal blood supply
- D They consume more oxygen than they extract from air
Correct answer: They collapse without water support
Gills require water to maintain their structure. On land, they collapse and lose effective surface area for gas exchange.
Which adaptation helps birds flying at high altitudes obtain sufficient oxygen?
- A Reduced lung size
- B Presence of air sacs
- C Lower hemoglobin affinity
- D Thicker blood plasma
Correct answer: Presence of air sacs
Air sacs allow continuous airflow through lungs. This enhances oxygen uptake even at high altitudes.
In fishes, oxygenated blood from gills is directly supplied to:
- A Lungs
- B Heart chambers
- C Body tissues
- D Kidneys first
Correct answer: Body tissues
In fishes, oxygenated blood flows directly from gills to body tissues. The heart pumps only deoxygenated blood.
Which statement best summarizes respiratory adaptations in high altitude and underwater environments?
- A Both rely on increased oxygen concentration in surroundings
- B Both involve reduced respiratory surface area
- C Both enhance oxygen uptake under low availability
- D Both eliminate the need for specialized respiratory organs
Correct answer: Both enhance oxygen uptake under low availability
Both environments present low oxygen availability. Organisms adapt by improving oxygen uptake and utilization efficiency.