Explanation

• The nucleus is the control center of the cell.
• It regulates all vital activities like growth, reproduction, and metabolism.
• It contains genetic material (DNA).
• Ribosomes make proteins, and cytoplasm supports cell structure.

Last verified on 04-05-2026

Explanation

• The longest cell in the human body is the nerve cell (neuron).
• Some neurons can extend up to 1 meter in length.
• They transmit impulses throughout the body.

Additional information:

• The smallest cell in the human body is the sperm cell (spermatozoon).
• It is measures approximately 4–5 micrometers (µm) in length.
• It is mainly consisting of a nucleus and a tail.

Last verified on 23-04-2026

Explanation

Chromosomes are made up of:

• Nucleic acid (DNA or RNA)
• Proteins (histones and non-histone proteins)

A chromosome is made up of proteins and DNA organized into genes.

Each cell normally contains 23 pairs of chromosomes.

Explanation

O negative (O⁻) blood group is called the universal donor.

It can be transfused to any blood group (A, B, AB, or O).

O⁻ lacks A, B, and Rh antigens, preventing immune reactions in recipients.

Explanation

The lifespan of white blood cells ranges from 13 to 20 days, after which time they are destroyed in the lymphatic system.

When immature WBCs are first released from the bone marrow into the peripheral blood, they are called "bands" or "stabs."