Human Physiology Practice Questions
IB (International Baccalaureate) · IB Biology HL · 142 free MCQs with instant results and detailed explanations.
142
Total
43
Easy
69
Medium
30
Hard
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Sample Questions from Human Physiology
Here are 10 sample questions. Start a quiz to get randomized questions with scoring.
Q1
Easy
Which of the following best describes the role of insulin in human physiology?
A.
It increases blood glucose levels.
B.
It decreases blood glucose levels.
C.
It catalyzes the digestion of proteins.
D.
It regulates body temperature.
Show Answer & Explanation
Correct Answer: B
Insulin is a hormone produced by the pancreas that helps to lower blood glucose levels by facilitating the uptake of glucose into cells and promoting its conversion to glycogen for storage.
Q2
Easy
What is the primary function of red blood cells in the human body?
A.
To fight infections.
B.
To transport oxygen.
C.
To regulate pH levels.
D.
To produce hormones.
Show Answer & Explanation
Correct Answer: B
Red blood cells (erythrocytes) are primarily responsible for transporting oxygen from the lungs to the tissues and returning carbon dioxide from the tissues back to the lungs for exhalation.
Q3
Easy
Which part of the human brain is primarily responsible for coordinating voluntary muscle movements?
A.
Cerebellum
B.
Cerebrum
C.
Hypothalamus
D.
Medulla oblongata
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Correct Answer: A
The cerebellum is responsible for coordinating voluntary movements, balance, and posture, allowing for smooth and precise motor control.
Q4
Medium
What role does the hypothalamus play in thermoregulation?
A.
It generates heat through metabolism.
B.
It acts as a thermostat regulating body temperature.
C.
It secretes hormones that decrease body temperature.
D.
It transmits nerve signals to cool the body.
Show Answer & Explanation
Correct Answer: B
The hypothalamus functions as the body's thermostat, detecting changes in temperature and activating mechanisms, such as sweating or shivering, to maintain a stable internal temperature.
Q5
Medium
During muscle contraction, which is the primary source of ATP production in muscle cells?
A.
Phosphocreatine breakdown
B.
Anaerobic glycolysis
C.
Aerobic respiration
D.
Fatty acid oxidation
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Correct Answer: C
Aerobic respiration is the primary source of ATP production during extended periods of muscle contraction, as it efficiently produces ATP in the presence of oxygen.
Q6
Medium
Which of the following statements about the structure of hemoglobin is correct?
A.
It consists of four identical polypeptide chains.
B.
It has a higher affinity for carbon dioxide than for oxygen.
C.
It binds oxygen more effectively at higher pH levels.
D.
It is only found in red blood cells of mammals.
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Correct Answer: C
Hemoglobin's affinity for oxygen increases at higher pH levels due to the Bohr effect, which enhances oxygen binding in the lungs where pH is higher.
Q7
Medium
What is the primary function of the villi in the small intestine?
A.
To secrete digestive enzymes.
B.
To increase surface area for absorption.
C.
To regulate peristalsis.
D.
To produce mucus for lubrication.
Show Answer & Explanation
Correct Answer: B
The villi in the small intestine increase the surface area, allowing for more efficient absorption of nutrients from digested food.
Q8
Hard
Which of the following correctly describes the role of the sinoatrial (SA) node in the human heart?
A.
It initiates the electrical impulse that triggers heart contractions.
B.
It receives blood from the pulmonary veins.
C.
It acts as a valve preventing backflow of blood.
D.
It regulates the flow of oxygenated blood to the body.
Show Answer & Explanation
Correct Answer: A
The sinoatrial (SA) node is known as the natural pacemaker of the heart as it initiates the electrical impulses that cause the heart to contract, leading to the heartbeat.
Q9
Hard
During aerobic respiration, how much ATP can theoretically be produced from one molecule of glucose?
A.
2 ATP
B.
30-32 ATP
C.
36-38 ATP
D.
12 ATP
Show Answer & Explanation
Correct Answer: C
The theoretical yield of ATP from one molecule of glucose during aerobic respiration can range from 36 to 38 ATP depending on the efficiency of the electron transport chain and the shuttle mechanisms used to transport electrons into the mitochondria.
Q10
Hard
In the human respiratory system, which mechanism primarily regulates the rate of breathing in response to increased carbon dioxide levels in the blood?
A.
Baroreceptor feedback
B.
Chemoreceptor feedback
C.
Stretch receptor feedback
D.
Corticosteroid feedback
Show Answer & Explanation
Correct Answer: B
Chemoreceptor feedback is responsible for detecting changes in carbon dioxide levels. When CO2 levels rise, chemoreceptors stimulate the respiratory center in the brain to increase the rate of breathing, ensuring that excess CO2 is expelled and oxygen intake is increased.
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Human Physiology — IB (International Baccalaureate) IB Biology HL Practice Questions Online
This page contains 142 practice MCQs for the chapter Human Physiology in IB (International Baccalaureate) IB Biology HL. The questions are organized by difficulty — 43 easy, 69 medium, 30 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.