What's covered
Key facts
Cells: structure and parts
In a bacterial cell, the genetic material sits free in the cytoplasm as a single loop of DNA.
Specialised cells and microscopy
Differentiation is the process by which a cell becomes specialised for a particular function.
Tissues, organs, organ systems
The circulatory system pumps blood around the body, delivering oxygen and nutrients and removing wastes.
Cells: structure and parts
Bacterial cells do not have a true nucleus — their DNA is not enclosed in a nuclear membrane.
Specialised cells and microscopy
An electron microscope uses beams of electrons instead of light, magnifying samples hundreds of thousands of times — enough to see inside organelles.
Tissues, organs, organ systems
The digestive system breaks food down into small molecules the body can absorb.
Cells: structure and parts
A cell is the smallest unit of life and the basic building block of every living organism.
Specialised cells and microscopy
A light microscope uses visible light and glass lenses to magnify a sample several hundred times.
Tissues, organs, organ systems
The endocrine system controls body processes by releasing hormones into the bloodstream.
Cells: structure and parts
The cell membrane controls what enters and leaves the cell.
Sample questions
A taste of the 31 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
What is a cell?
- •A chemical product
- •A type of tissue
- •An organ in body
- ✓Smallest unit of life
Why are red blood cells suited to their job?
- ✓Biconcave disc, no nucleus, packed with haemoglobin
- •Large central vacuole that holds water reserves
- •Long tail to swim through veins quickly
- •Spherical with very thick cell walls outside
What is a tissue?
- •A single cell with many roles
- •Group of organs in the body
- ✓Group of similar cells working together
- •Part of the cell membrane
Which structure is found in plant cells but NOT animal cells?
- •Cell membrane
- ✓Chloroplast
- •Mitochondria
- •Nucleus
Why do sperm cells have a long tail?
- •To absorb nutrients
- •To carry oxygen around
- •To divide rapidly
- ✓To swim toward the egg cell
What is an organ system?
- •Cells joined by chemical bonds
- •One organ with many tissues
- ✓Organs working together for one purpose
- •The body's blood supply only
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