Edexcel Biology B1, classification

Topic One of Edexcel B1: classification.

Might be slightly helpful..

  • Created by: Nori
  • Created on: 25-04-14 18:48

Classification of organisms- The Five Kingdoms

Organisms are classified into The Five Kingdoms:

  • Animalia- multicellular, do not have cell walls, do not have chlorophyll, feed heterotrophically (unable to make own food)
  • Plantae- multicellular, have cell walls, have chlorophyll, feed autotrophically (make their own food, by photosynthesis)
  • Fungi- multicellular, have cell walls, do not have chlorophyll, feed saprophytically (feed off of dead organisms/ decaying material)
  • Protoctista- unicellular, has a nucleus, an example is algae
  • Prokaryotes- unicellular, do not have a nucleus, an example is bacteria

The Five Kingdoms are subdivided into:

  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
1 of 4

Classification of organisms- Viruses

  • Viruses are considered as being non-living.
  • They are unable to reproduce themselves, so invade cells to make them reproduce the virus.

For this reason, viruses are not classified into any of the five kingdoms.

2 of 4

Classification of organisms- The phylum Chordata

The phylum Chordata contains animals that have a supporting rod running the length of their bodies, for example the backbone in vertebrates.

Vertebrates are divided into 5 classes:

  • Amphibians
  • Birds
  • Fish
  • Mammals
  • Reptiles

Which group a vertebrate is in depends on:

  • Oxygen absorption methods- lungs, gills, skin
  • Reproductive methods- internal or external fertilisation, oviparous or viviparous
  • Thermoregulation- homeotherms or poikilotherms

However some vertebrates are difficult to classify- e.g. the duck-billed platypus.

3 of 4

Classification of organisms- species

The term species is often defined as "organisms that produce fertile offspring".

Limitations of this definition:

  • Not all organisms produce sexually so some hybrids are fertile.
  • Some organisms can produce asexually but are still classed as the same species.
  • Many closely related species can interbreed producing offspring that is classed as another species.
  • Closely related species can sometimes produce fertile offsping, for example in some species of duck.
4 of 4


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Variety of life and classification resources »