All Free Biology MCQs with Answers
Every Biology question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
19,844 questions · page 811 of 993
- A. 11%
- B. 12%
- C. 15%
- D. 16%
Explanation: The amount gases in exhaled air are 4% to 5% by volume more carbon dioxide and 4% to 5% by volume less oxygen than was inhaled.
Correct answer: 16%- A. Ribs
- B. Pharynx
- C. Lungs
- D. Both B and C
Explanation: Intercostal muscles are muscles that present within the rib cage. Consist of three layers of muscles external, internal, and innermost…
Correct answer: Ribs- A. Decrease in Temperature
- B. Increase in pH
- C. Decrease in CO2 Concentration
- D. Decrease in pH
Explanation: "The explanation for this question will be added soon!".
Correct answer: Decrease in pH- A. More dome like
- B. Less dome like
- C. Less flat
- D. Convex
Explanation: When the muscles of the diaphragm contract, it becomes less domed and more flattened.
Correct answer: Less dome like- A. Bright red oxyhemoglobin
- B. Purple red oxyhemoglobin
- C. Bright red hemoglobin
- D. Purple red hemoglobin
Explanation: Hemoglobin readily combines with oxygen to form "oxyhemoglobin." Oxyhemoglobin is the complex that is formed when oxygen molecules bind to…
Correct answer: Bright red oxyhemoglobin- A. Carboxylase
- B. Oxygenase
- C. Anhydrase
- D. Deoxygenase
Explanation: The enzyme that is involved in the dissociation of oxygen from hemoglobin is called "carbonic anhydrase." This enzyme catalyzes the…
Correct answer: Anhydrase- A. Asthma
- B. Respiratory distress syndrome
- C. Emphysema
- D. Sinusitis
Explanation: Deficiency of surfactant in infants can lead to a condition called "Respiratory Distress Syndrome" (RDS), also known as "Hyaline Membrane…
Correct answer: Respiratory distress syndrome- A. Air sacs
- B. Bronchioles
- C. Alveoli
- D. Bronchi
Explanation: The functional unit of the lungs is called the "alveolus" (plural: alveoli).
Correct answer: Air sacs- A. Nostril
- B. Glottis
- C. Nares
- D. Epiglottis
Explanation: The opening of the larynx is called the "glottis." The glottis is the space between the vocal cords, and it plays a crucial role in…
Correct answer: Glottis- A. Nostrils
- B. Pharynx
- C. Nasal cavities
- D. Nose
Explanation: Nose has two openings called nostrils. Nostrils have fine hair to trap dust particles present in the air and stops them from entering our…
Correct answer: Nostrils- A. Two passageways
- B. Three passageways
- C. Four passageways
- D. Five passageways
Explanation: To summarize, the correct answer is b) Three passage ways, as in each cavity there are three regions; nasal vestibule, respiratory region…
Correct answer: Three passageways- A. Its red colour
- B. Presence of iron
- C. Its ability to combine reversibly with oxygen
- D. Presence of basic protein globin
Explanation: The correct answer is c) Its ability to combine reversibly with oxygen.
Correct answer: Its ability to combine reversibly with oxygen- A. Directly proportional to CO2 concentration
- B. Indirectly proportional to CO2 concentration
- C. Inversely proportional to CO2 concentration
- D. Independent of CO2 concentration
Explanation: The correct answer is d) Independent of CO2 Concentration. Oxygen binding to hemoglobin is influenced by factors like partial pressure of…
Correct answer: Inversely proportional to CO2 concentration- A. pH of blood falls
- B. pH of blood rises
- C. CO2 concentration in blood falls
- D. Free fatty acid concentration in blood falls
Explanation: "The explanation for this question will be added soon!".
Correct answer: pH of blood falls- A. One
- B. Two
- C. Three
- D. Four
Explanation: "The explanation for this question will be added soon!".
Correct answer: Four16216. Blood transport of CO2 occurs in three forms. The correct percentages of CO2 in these forms are:
- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: "The explanation for this question will be added soon!".
Correct answer: Option A- A. O2 concentration is high and CO2 is low.
- B. O2 concentration is low and CO2 is high.
- C. O2 tension is high and CO2 tension is low.
- D. O2 tension is low and CO2 tension is high.
Explanation: "The explanation for this question has been added!".
Correct answer: O2 concentration is high and CO2 is low.- A. Downward movement of diaphragm
- B. Upward movement of diaphragm
- C. Upward movement of the ribs
- D. Downward movement of the diaphragm and upward movement of ribs
Explanation: "The explanation for this question will be added soon!".
Correct answer: Downward movement of the diaphragm and upward movement of ribs16219. Each bronchus on entering the lung divides and sub-divides progressively into smaller and smaller:
- A. Bronchioles
- B. Bronchi
- C. Alveolar ducts
- D. Tracheoles
Explanation: "The explanation for this question will be added soon!".
Correct answer: Bronchioles- A. With the help of RBCs and blood plasma
- B. With the help of RBCs and WBCs
- C. With the help of WBCs and blood serum
- D. With the help of platelets and corpuscles
Explanation: "The explanation for this question will be added soon!".
Correct answer: With the help of RBCs and blood plasma