Cell, Human Body and Nutrition Basics

Biology Basics: Cell, Human Body and Nutrition

The cell

• The cell is the basic structural and functional unit of life (discovered by Robert Hooke, 1665).
• Mitochondria – powerhouse of the cell (makes ATP).
• Ribosomes – protein synthesis. Nucleus – control centre, holds DNA.
• Lysosomes – "suicide bags". Plant cells additionally have a cell wall and chloroplasts.

Human body facts

• Largest gland: Liver. Largest organ: Skin. Smallest bone: Stapes (ear).
• Adult human has 206 bones. Normal body temperature ≈ 37°C (98.6°F).
• Blood: RBCs carry oxygen (haemoglobin), WBCs fight infection, Platelets help clotting.
• Universal donor: O negative; universal recipient: AB positive.

Vitamins and deficiency diseases

Vitamin	Deficiency disease
A	Night blindness
B1	Beriberi
C	Scurvy
D	Rickets
K	Poor blood clotting

Exam tips

• Learn "largest/smallest" facts and vitamin–disease pairs; they appear every year.

Analogy

Think of a cell as a railway station. The nucleus is the station master's office that holds the rulebook (DNA) and gives orders. Mitochondria are the power house supplying electricity to run everything. Ribosomes are the workshops building parts (proteins). The cell membrane is the ticket gate deciding who enters and leaves. In the body, blood is the train network: RBCs are goods trains carrying oxygen, WBCs are the RPF guards, and platelets are the repair crew that seal a broken track.