Chapter 19: Diversity of Life

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Introduction:

Life on Earth is amazingly diverse.

In order to make it simpler to study and describe life, scientists have devised a system of classifying living organisms. All living organisms can be classified into one of five groups, called kingdoms.

  • Taxonomy: study of the classification of living organisms.

The five kingdoms of life

Monera:

Monera: all bacteria – the most numerous organisms, as well as having the greatest biomass, on Earth.

Bacteria

Protista:

Protista: small single-celled organisms such as Amoeba, Cryptosporidium and algae (such as seaweeds).

  • They are all aquatic-based
  • Some are autotrophic (e.g. algae); some are heterotrophic (e.g. Amoeba)
  • Some are multicellular (e.g. seaweeds); some are single celled (e.g. Amoeba)
  • Some reproduce asexually (e.g. Amoeba); some reproduce sexually (e.g. seaweeds)
Amoeba

Fungi:

Fungi: single-celled or multicellular heterotrophic organisms such as yeasts, moulds and mushrooms.

  • They all possess chitin in their cell walls
  • They are all heterotrophic
  • They all reproduce by means of spores – by producing the spores either by asexual or sexual reproduction

Plantae:

Plantae: Multi-cellular photosynthetic organisms.

  • They are all multicellular
  • They are all photosynthetic
  • They all have cellulose in their cell walls
  • They all have vacuoles for storage in their cells
  • They can reproduce asexually or sexually

Animalia:

Animalia: Multi-cellular heterotrophic organisms.

  • They are all multicellular
  • They are all heterotrophic
  • They all reproduce sexually