The Five Kingdoms (Cambridge O Level Biology)

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Cara Head

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Cara Head

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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

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 cellA typical plant cell

  • 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

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

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

A typical bacterial cell

The Animal Kingdom

  • Several main features are used to place organisms into groups within the animal kingdom

Vertebrates

  • All vertebrates have a backbone
    • There are 5 classes of vertebrates
Class Main Features Examples
Mammals
  • Fur/hair on skin
  • Gives birth to live young
  • Have placenta
  • Produces milk to feed young
  • External ears visible
  • Endothermic
Human, dog, mouse, horse
Birds
  • Feathers cover skin
  • Have two legs and two wings, instead of forelimbs
  • Lay eggs with hard shell on land
  • Have a beak
  • Endothermic
Eagle, hen, duck, pigeon
Reptiles
  • Dry, fixed scales on skin
  • Lay eggs with rubbery shell on land
Snake, lizard, turtle
Amphibian
  • Smooth, moist skin
  • Lays eggs without shells in water
  • Adults live on land (no gills), larvae live in water (have gills)
Frog, toad, newt
Fish
  • Loose, wet scales on skin
  • Lays eggs without shells in water
  • Gills to breathe
Flounder, tuna, clown fish

 

Vertebrate Classification

Vertebrate classification

Invertebrates

  • Invertebrates do not possess a backbone
  • One of the morphological characteristics used to classify invertebrates is whether they have legs or not
  • All invertebrates with jointed legs are part of the arthropod phylum
  • They are classified further into the following groups:

Invertebrate Table 

Group Main Features Example
Myriapods
  • Body consists of many segments
  • Each segment contains at least one pair of jointed legs
  • One pair of antennae
Centipede
Insects
  • Three part body: head, thorax, abdomen
  • Three pairs of jointed legs
  • Two pairs of wings (these may be non-functional and/or underdeveloped)
  • One pair of antennae
Butterfly, ant, wasp
Arachnids
  • Two body parts: Cephalothorax and abdomen
  • Four pairs of jointed legs
  • No antennae
Spider, scorpion, tick
Crustaceans
  • More than four pairs of jointed legs
  • Chalky exoskeleton formed from calcium
  • Breathe through gills
  • Two pairs of antennae
Crab, lobster

 Arthropod Classification Arthropod classification

The Plant Kingdom

  • At least some parts of any plant are green, caused by the presence of the pigment chlorophyll which absorbs energy from sunlight for the process of photosynthesis
  • The plant kingdom includes organisms such as ferns and flowering plants

 Ferns

  • Have leaves called fronds
  • Do not produce flowers but instead reproduce by spores produced on the underside of fronds

Ferns

Ferns reproduce by spores found on the underside of their fronds

Ferns reproduce by spores found in the underside of their fronds

Flowering plants

  • Reproduce sexually by means of flowers and seeds
  • Seeds are produced inside the ovary found at the base of the flower
  • Can be divided into two groups – monocotyledons and dicotyledons

Wheat plants are monocotyledons

Wheat plants are monocotyledons

Sunflowers are dicotyledons

Sunflowers are dicotyledons

How do you distinguish between monocotyledons and dicotyledons?

1) Flowers

  • Flowers from monocotyledons contain petals in multiples of 3
  • Flowers from dicotyledons contain petals in multiples of 4 or 5

2) Leaves

  • Leaves from monocotyledons have parallel leaf veins
  • Leaves from dicotyledons have reticulated leaf veins (meaning that they are all interconnected and form a web-like network throughout the leaf)

Comparing monocots and dicots

Comparing monocots and dicots

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Cara Head

Author: Cara Head

Expertise: Biology

Cara graduated from the University of Exeter in 2005 with a degree in Biological Sciences. She has fifteen years of experience teaching the Sciences at KS3 to KS5, and Psychology at A-Level. Cara has taught in a range of secondary schools across the South West of England before joining the team at SME. Cara is passionate about Biology and creating resources that bring the subject alive and deepen students' understanding