Explanation

• Cell biology  is a branch of biology that studies the structure, function, and behavior of cells.
• All living organisms are made of cells.
• Also cellular biology or cytology
  

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

• O⁻ (O Negative) is the universal donor blood group.
• It can be transfused to A, B, AB, and O blood groups.
• O⁻ blood lacks A, B, and Rh (D) antigens.

Additional information:

• Universal Recipient: AB⁺ (AB Positive)
• ABO Blood Groups: A, B, AB, O
• Rh Types: Positive (+) and Negative (−)
• Total Common Blood Groups: 8 (A⁺, A⁻, B⁺, B⁻, AB⁺, AB⁻, O⁺, O⁻)

Last verified on 14-07-2026

Explanation

• Blood is red because of a protein called hemoglobin inside our red blood cells,
• Which contains iron that changes color when it binds to oxygen

Last updated by NS on 5-09-2026

Explanation

• The ovum (egg cell) is generally considered the largest cell in the human body.
• It is the female reproductive cell and can be seen with the naked eye as a tiny dot.
• The ovum is approximately 0.1 mm (100 micrometers) in diameter.
• In contrast, the sperm cell is one of the smallest human cells.

Last verified on 03-09-2026