IGCSE Biology: Cell Structure and Functions Study Notes

Biology: Cell Structure and Functions (IGCSE / High School Level)

Overview
Cells are the basic units of life. There are two main types: prokaryotic (bacteria) and
eukaryotic (animal and plant) cells. Understanding the structure and function of each part is
essential for exams.

Key Cell Structures and Functions
Organelle Function
Cell membrane Controls what enters and leaves the cell
Cytoplasm Jelly-like fluid where chemical reactions
happen
Nucleus Contains DNA; controls the cell’s activities
Mitochondria Site of aerobic respiration, producing
energy
Ribosomes Makes proteins
Cell wall (Plant only) Provides strength and support
Chloroplasts (Plant only) Site of photosynthesis;
contains chlorophyll
Vacuole (Plant only) Stores cell sap; helps maintain
shape

Prokaryotic vs Eukaryotic Cells
Feature Prokaryotic Eukaryotic
Nucleus No (DNA is free in Yes (DNA enclosed in
cytoplasm) nuclear membrane)
Size Small Larger
Organelles Few Many (mitochondria, etc.)
Example Bacteria Animal, plant, fungi

Exam Tip
Always mention function + location in your answers. For example:
“Mitochondria are the site of aerobic respiration, providing energy for the cell.”

Sample Question
Q: Describe two differences between animal and plant cells.
A:
- Plant cells have a cell wall, animals do not.
- Plant cells contain chloroplasts for photosynthesis; animal cells don’t.