CIE IGCSE Biology

Revision Notes

1.3 Features of Organisms

Common Cell Structures

  • The cells of all living organisms contain the following:
    • Cytoplasm
    • Cell membrane
    • DNA as genetic material (either found in the nucleus or free in the cytoplasm)

 

General Cell Features, IGCSE & GCSE Biology revision notes

General cell features

 

Typical animal and plant cells, IGCSE & GCSE Biology revision notes

A typical animal cell and plant cell

 

A typical prokaryotic cell, IGCSE & GCSE Biology revision notes

A typical prokaryotic cell

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Cell Composition & Structure

  • When viewed under an electron microscope (at a much higher magnification), all cells also contain the following:
    • Ribosomes for protein synthesis
    • Enzymes for respiration (in many, but not all types of cells, found in mitochondria

The Five Kingdoms

  • The first division of living things in the classification system is to put them into one of five kingdoms. They are:
    • Animals
    • Plants
    • Fungi
    • Protoctists
    • Prokaryotes

 

  • Main features of all animals:
    • they are multicellular
    • their cells contain a nucleus but no cell walls or chloroplasts
    • they feed on organic substances made by other living things

 

A typical animal cell, IGCSE & GCSE Biology revision notes

A typical animal cell

  • Main features of all plants:
    • they are multicellular
    • their cells contain a nucleus, chloroplasts and cellulose cell walls
    • they all feed by photosynthesis

 

A typical plant cell, IGCSE & GCSE Biology revision notes

A typical plant cell

 

Extended Only

Fungi, Protoctists & Prokaryotes

  • Main features of all fungi (e.g. moulds, mushrooms, yeast)
    • usually multicellular
    • cells have nuclei and cell walls not made from cellulose
    • do not photosynthesize but feed by saprophytic (on dead or decaying material) or parasitic (on live material) nutrition

 

A typical fungal cell, IGCSE & GCSE Biology revision notes

A typical fungal cell

 

  • Main features of all Protoctists (e.g. Amoeba, Paramecium, Plasmodium)
    • most are unicellular but some are multicellular
    • all have a nucleus, some may have cell walls and chloroplasts
    • meaning some protoctists photosynthesise and some feed on organic substances made by other living things

 

Two examples of protoctist cells, IGCSE & GCSE Biology revision notes

Two examples of protoctist cells

 

  • Main features of all Prokaryotes (bacteria, blue-green algae)
    • often unicellular
    • cells have cell walls (not made of cellulose) and cytoplasm but no nucleus or mitochondria

 

A typical bacterial cell, IGCSE & GCSE Biology revision notes

A typical bacterial cell

Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.
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