Respiration MCQs

51. What is the main respiratory pigment in humans?
A. Chlorophyll
B. Hemoglobin
C. Myoglobin
D. Carotene
Answer: B
Where is hemoglobin found?
A. Plasma
B. White blood cells
C. Red blood cells
D. Platelets
Answer: C
What is the function of red blood cells?
A. Fight infection
B. Carry oxygen
C. Clot blood
D. Produce hormones
Answer: B
Which structure prevents food from entering the trachea?
A. Epiglottis
B. Larynx
C. Pharynx
D. Bronchus
Answer: A
What is the voice box called?
A. Trachea
B. Larynx
C. Bronchi
D. Alveoli
Answer: B
What is the windpipe called?
A. Bronchus
B. Trachea
C. Larynx
D. Pharynx
Answer: B
Which structures branch from the trachea?
A. Bronchi
B. Alveoli
C. Capillaries
D. Veins
Answer: A
What is the smallest respiratory unit in lungs?
A. Bronchi
B. Bronchioles
C. Alveoli
D. Trachea
Answer: C
What is the function of alveoli?
A. Pump blood
B. Gas exchange
C. Store oxygen
D. Filter air
Answer: B
Why are alveoli efficient?
A. Thick walls
B. Large surface area
C. Small size
D. Low blood supply
Answer: B
Which gas is transported by plasma?
A. Oxygen
B. Carbon dioxide
C. Nitrogen
D. Hydrogen
Answer: B
What percentage of oxygen is carried by hemoglobin?
A. 50%
B. 70%
C. 98%
D. 100%
Answer: C
What happens during exhalation?
A. Diaphragm contracts
B. Chest expands
C. Diaphragm relaxes
D. Air enters lungs
Answer: C
What is vital capacity?
A. Normal breath volume
B. Maximum air expelled after inhalation
C. Residual air
D. Dead space
Answer: B
Which condition is caused by lack of oxygen?
A. Anemia
B. Hypoxia
C. Asthma
D. Pneumonia
Answer: B
What is the role of nasal cavity?
A. Digestion
B. Filter and warm air
C. Pump blood
D. Produce enzymes
Answer: B
What is diffusion?
A. Movement of water
B. Movement from high to low concentration
C. Active transport
D. Osmosis
Answer: B
Which organ removes carbon dioxide?
A. Liver
B. Lungs
C. Kidney
D. Heart
Answer: B
What is anaerobic respiration in yeast called?
A. Glycolysis
B. Fermentation
C. Oxidation
D. Reduction
Answer: B
Which energy carrier is used in cells?
A. DNA
B. RNA
C. ATP
D. ADP
Answer: C
What is produced per glucose in aerobic respiration?
A. 2 ATP
B. 4 ATP
C. 36–38 ATP
D. 100 ATP
Answer: C
What is the main waste of respiration?
A. Oxygen
B. Carbon dioxide
C. Nitrogen
D. Hydrogen
Answer: B
What is breathing also called?
A. Circulation
B. Ventilation
C. Digestion
D. Absorption
Answer: B
Which part connects bronchi to alveoli?
A. Bronchioles
B. Trachea
C. Pharynx
D. Larynx
Answer: A
What is emphysema?
A. Infection
B. Lung disease damaging alveoli
C. Heart disease
D. Blood disease
Answer: B
What causes asthma?
A. Infection
B. Narrow airways
C. Lack of blood
D. Low oxygen
Answer: B
What is pneumonia?
A. Viral infection
B. Lung infection
C. Heart disease
D. Brain disease
Answer: B
What is smoking effect on lungs?
A. Improves oxygen
B. Damages alveoli
C. Increases airflow
D. Strengthens lungs
Answer: B
What is the role of capillaries in lungs?
A. Store oxygen
B. Gas exchange
C. Pump blood
D. Produce cells
Answer: B
What type of respiration occurs in bacteria?
A. Only aerobic
B. Only anaerobic
C. Both
D. None
Answer: C
Which molecule accepts electrons in ETC?
A. CO₂
B. Oxygen
C. Water
D. Glucose
Answer: B
What is water formed from in respiration?
A. CO₂
B. Oxygen + Hydrogen
C. Glucose
D. ATP
Answer: B
Which step releases CO₂?
A. Glycolysis
B. Krebs cycle
C. ETC
D. Fermentation
Answer: B
Which process does not require oxygen?
A. Aerobic respiration
B. Krebs cycle
C. Glycolysis
D. ETC
Answer: C
What is pyruvate converted into in anaerobic conditions (muscle)?
A. Ethanol
B. Lactic acid
C. Glucose
D. CO₂
Answer: B
What happens to breathing during exercise?
A. Decreases
B. Increases
C. Stops
D. Remains same
Answer: B
What is oxygen debt?
A. Lack of oxygen after exercise
B. Excess oxygen
C. Normal breathing
D. Air pressure
Answer: A
What is the respiratory quotient (RQ)?
A. CO₂/O₂ ratio
B. O₂/CO₂ ratio
C. ATP/Glucose
D. CO₂/ATP
Answer: A
RQ for carbohydrates is:
A. 0.7
B. 0.8
C. 1.0
D. 1.5
Answer: C
RQ for fats is approximately:
A. 1.0
B. 0.7
C. 0.5
D. 1.2
Answer: B
Which cells need more energy?
A. Skin cells
B. Muscle cells
C. Fat cells
D. Bone cells
Answer: B
What increases CO₂ in blood?
A. Exercise
B. Sleep
C. Rest
D. Meditation
Answer: A
What happens if CO₂ increases?
A. Breathing slows
B. Breathing increases
C. Stops breathing
D. No effect
Answer: B
What is the function of intercostal muscles?
A. Digest food
B. Help breathing
C. Pump blood
D. Produce energy
Answer: B
Where are intercostal muscles located?
A. Abdomen
B. Between ribs
C. Neck
D. Back
Answer: B
What happens to ribs during inhalation?
A. Move down
B. Move up and out
C. Stay still
D. Collapse
Answer: B
What is cyanosis?
A. Blue skin due to low oxygen
B. Red skin
C. Yellow skin
D. Green skin
Answer: A
Which system transports gases?
A. Nervous system
B. Circulatory system
C. Digestive system
D. Excretory system
Answer: B
What is the main energy source for respiration?
A. Protein
B. Glucose
C. Vitamin
D. Mineral
Answer: B
100. What is the ultimate goal of respiration?
A. Produce oxygen
B. Produce ATP
C. Store glucose
D. Remove nitrogen
Answer: B