Human Biology MCQs

Correct Answer: Liver

The liver is the largest gland (and largest internal organ) in the human body.

Correct Answer: Heart

The heart pumps blood around the body.

Correct Answer: Enamel

Tooth enamel is the hardest substance in the human body, harder than bone.

Correct Answer: Hinge Joint

The elbow joint is a classic example of a hinge joint, which allows movement in only one plane (flexion and extension), similar to the hinge of a door.

Correct Answer: Hydrochloric acid

The stomach produces hydrochloric acid (HCl), which breaks down food and activates digestive enzymes like pepsin.

Correct Answer: Pancreas

The pancreas secretes insulin from the beta cells located in the Islets of Langerhans to regulate blood glucose levels.

Correct Answer: Electroencephalogram (EEG)

An electroencephalogram (EEG) is a test that detects electrical activity in the brain using small, metal discs attached to the scalp.

Correct Answer: Leukocytes

Leukocytes, or white blood cells, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders.

Correct Answer: Tooth Enamel

Tooth enamel is the hardest and most highly mineralized substance in the human body.

Correct Answer: Calcium

Calcium is a crucial mineral required for the healthy development of bones and teeth, as well as enabling blood clotting and muscle contractions.

Correct Answer: 15 to 30 seconds

In human psychology, short-term memory acts as a scratchpad for temporary recall of information and generally lasts for about 15 to 30 seconds without rehearsal.

Correct Answer: 120/80 mmHg

A normal human blood pressure reading is typically around 120 over 80 millimeters of mercury (systolic/diastolic).

Correct Answer: Stroke volume

Stroke volume is the volume of blood pumped from the left ventricle per beat, critical for assessing cardiac function.

Correct Answer: 90%

Blood plasma is the yellowish liquid component of blood that holds the blood cells, consisting of about 90% to 92% water.

Correct Answer: Calcium Oxalate

The most common type of kidney stone is made of calcium oxalate, a compound formed when calcium binds with oxalate in urine.

Correct Answer: Hormones

Hormones are chemical messengers secreted directly into the bloodstream by endocrine glands to regulate physiology and behavior.

Correct Answer: 14-18 times

A normal resting respiratory rate for healthy adults is typically between 12 to 20 breaths per minute.

Correct Answer: Oxygen

By mass, oxygen makes up about 65% of the human body, primarily as a component of water.

Correct Answer: Eye lid

The eyelid has a highly active and necessary function (protecting the eye), unlike vestigial organs like the appendix or coccyx (tailbone) which have lost their original evolutionary function.

Correct Answer: Dental enamel

Dental enamel, the outer layer of teeth, is the hardest and most highly mineralized substance in the human body.

Correct Answer: Antigen

Blood types (A, B, AB, and O) are classified based on the presence or absence of inherited antigenic substances on the surface of red blood cells.

Correct Answer: Calcium Oxalate

The most common type of kidney stones are calcium stones, which are generally made of calcium oxalate.

Correct Answer: Urea

The human liver converts highly toxic ammonia into urea, which is then filtered by the kidneys and excreted in urine.

Correct Answer: Hemophilia

Hemophilia is a rare genetic disorder in which blood doesn't clot normally because it lacks sufficient blood-clotting proteins.

Correct Answer: 310

Normal human body temperature is approximately 37°C. Converted to Kelvin (37 + 273.15), it is roughly 310 K.

Correct Answer: Protein

Blood clotting involves coagulation factors, which are primarily proteins like fibrinogen that transform into a fibrin mesh.

Correct Answer: None of these

Hemostasis relies on blood platelets and proteins like fibrinogen, not enzymes like amylase or lipase, nor carbohydrates like starch.

Correct Answer: 120 days

The average lifespan of a human red blood cell (erythrocyte) is about 120 days.

Correct Answer: Concave lens

Myopia, where distant objects appear blurry, is corrected using a diverging or concave lens to move the focal point back onto the retina.

Correct Answer: 120 days

Human red blood cells (erythrocytes) have an average lifespan of about 100 to 120 days in the bloodstream.

Correct Answer: O-ve

Blood type O negative is considered the universal donor type because its red blood cells lack A, B, and Rh antigens, making it safe for transfusion to any blood group.

Correct Answer: 5-21 days

The lifespan of most white blood cells falls roughly within the range of 5 to 21 days, though some memory cells live for years.

Correct Answer: Bone Marrow

The primary site of red blood cell production (erythropoiesis) in adults is the red bone marrow.

Correct Answer: 1.5 kg

The average adult human brain weighs roughly between 1.3 to 1.5 kilograms.

Correct Answer: Hepatitis

SGOT (also known as AST) is an enzyme primarily found in the liver and heart. Highly elevated levels typically indicate liver damage or inflammation, such as Hepatitis.

Correct Answer: Goitre

A lack of dietary iodine leads to iodine deficiency, the most common visible symptom of which is a goiter—an abnormal enlargement of the thyroid gland.

Correct Answer: Vitamin D

When bare skin is exposed to UVB rays from the sun, the body naturally synthesizes Vitamin D.

Correct Answer: To express our feelings

Laughter is a physical reaction in humans consisting of rhythmic, often audible contractions of the diaphragm and other parts of the respiratory system to express joy or amusement.

Correct Answer: White blood cells

White blood cells (leukocytes) are part of the body's immune system, helping protect against infectious diseases and foreign invaders.

Correct Answer: Veins

Veins are blood vessels that carry deoxygenated blood from the tissues back to the heart.

Correct Answer: Fluorine

Fluorine (in the form of fluoride) hardens tooth enamel; its deficiency makes teeth more susceptible to decay.

Correct Answer: Full body paralysis

Tetraplegia, also known as quadriplegia, is the paralysis of all four limbs and the torso, usually caused by spinal cord injury.

Correct Answer: Kidney

While the liver metabolizes drugs, the kidneys play the primary crucial role in filtering out these waste metabolites and excreting them via urine.