Explanation

• WBCs survive for about 13–20 days, depending on the type.
• WBCs are also called Leukocytes.
• They protect the body against infections.
• They are produced in the bone marrow.

Important Note: The 13–20 days lifespan is not applicable to all WBCs; their lifespan varies according to type.

Explanation

• Nitrous oxide, commonly known as laughing gas.
• It is a colorless, non-flammable gas used in medicine.
• Nitrous oxide (N₂O) causes temporary laughing and relaxation.

Additional information:

• Nitrous oxide was discovered by Joseph Priestley in 1772.

Last verified on 18-01-2026

Explanation

The least count of a Vernier caliper is 0.1 mm (or 0.01 cm).

It is the smallest measurement that can be accurately read using the instrument.

It is derived from the difference between one main scale reading and one Vernier scale reading.

It is commonly used to accurately measure outside diameters of shafts, thicknesses of various parts, diameters of holes or rings, internal dimensions of hollow jobs, and depths of holes or steps. 

Explanation

Vitamin B Complex deficiency, specifically Vitamin B1 (Thiamine) deficiency, can cause:

Beriberi, a disease characterized by:

• Fatigue and weakness
• Nerve damage and pain
• Heart problems
• Swelling of legs and feet

Additional information:

• Vitamin B3 (Niacin) deficiency → Pellagra
• Vitamin B12 deficiency → Megaloblastic anemia and neurological problems

Last verified on 01-10-2026

Explanation

• Residual volume (RV) is the volume of air that remains in the lungs after maximum forced expiration.
• It cannot be voluntarily exhaled completely.
• It helps prevent the lungs from collapsing.
• It is different from normal tidal breathing.

Last verified on 01-10-2026

Explanation

• The two strands of DNA run in opposite directions (5' to 3' on one strand and 3' to 5' on the other).
• This orientation is known as antiparallel.
• It is crucial for proper DNA replication and function.

Last verified on 01-10-2026

Explanation

• The nucleus contains the cell’s genetic material (DNA).
• DNA carries hereditary information.
• The nucleus controls many cell activities.
• In prokaryotic cells (like bacteria), DNA is not enclosed in a nucleus; it is found in the nucleoid region.
• Genetic material = DNA.

Explanation

• Total bones in adult human body = 206
• At birth = 270–300 bones (fuse to become 206)

The total bones of our body can be divided into:

• Axial skeleton = 80 bones
• Appendicular skeleton = 126 bones

Additional information:

• Newborn baby has 300 bones
• Longest bone = Femur
• Shortest bone = Stapes
• Bones in human skull = 22

Last verified on 30-03-2026

Explanation

• Inventor: Thomas Alva Edison.
• Country: United States.
• Practical incandescent bulb: 1879.
• Other contributions: Electric power, sound recording, motion pictures.
• Famous invention: Phonograph.

Last verified on 03-09-2026

Explanation

• Mercury is the closest planet to the Sun, followed by Venus.
• Called an inner planet because it orbits inside Earth’s orbit.
• Number of moons: 0 (Mercury has no natural satellites).
• Size: Smallest planet in the solar system.
• Nickname: Swift Planet, due to its fast orbit around the Sun (≈88 days per orbit).

Last verified on 17-03-2026