9.4 Five kingdom system

Kingdom Monera (ESGBZ)

The Kingdom Monera consists of prokaryotic, unicellular organisms. No nuclear membrane or membrane-bound organelles such as chloroplasts, Golgi complex, mitochondria or endoplasmic reticulum are present. Monera have a cell wall of protein plus polysaccharide compound, but not cellulose. They reproduce asexually by binary fission. Important examples of Monera include Archaea and Bacteria.

Kingdom Protista (ESGC2)

Protista are eukaryotic and can be unicellular or simple multicellular. They reproduce sexually or asexually. Important examples of protists include the organism known as Plasmodium (which causes malaria), Amoeba and Euglena. There are two major groups of protists which include the Protozoans, whose cells are similar to animal cells in that they do not have cell walls and the plant-like cells which do have cell walls and are similar to algae.

Kingdom Fungi (ESGC3)

Fungi are eukaryotic organisms that can be multicellular or unicellular. Mushrooms and moulds are examples of multicellular fungi and yeast is an example of a unicellular fungi. All fungi have a cell wall made of chitin. They are non-motile (not capable of movement) and consist of threads called hyphae. Fungi are heterotrophic organisms which means they require organic compounds of carbon and nitrogen for nourishment. They are important as decomposers (saprophytes) and can be parasitic. They store carbon as glycogen, not in the form of starch. Fungi reproduce sexually and asexually by spore formation. An important example of a useful fungus is Penicillium (a fungus which was used to make penicillin, one of the most powerful antibiotics ever created).

Kingdom Plantae (ESGC4)

Organisms belonging to the plant kingdom are eukaryotic and multicellular organisms. They have a distinct cell wall made of cellulose. Cells are organised into true plant tissues. Plants contain plastids and photosynthetic pigments such as chlorophyll. They are non-motile. Plants make their own food by photosynthesis and are therefore said to be autotrophic. Plants undergo both sexual and asexual reproduction. They store food as starch. Important examples of plants are mosses, ferns, conifers and flowering plants.

Examples of plant variety

Kingdom Animalia (ESGC5)

Members of the animal kingdom are eukaryotic and multicellular but have no cell wall or photosynthetic pigments. They are mostly motile and they are heterotrophic, which means they must feed on other organisms and cannot make their own food. They reproduce sexually or asexually. Animals store carbon as glycogen and fat. Important examples of this kingdom include: Porifera (sponges), Cnidaria (jellyfish), Nematoda (nematode worms), Platyhelminthes (flatworms), Annelidas (segmented worms), Mollusca (Snails and Squid), Echinodermata (starfish), Arthropoda (Insects and Crustaceans), Chordata (includes all the vertebrates: fish, amphibians, reptiles, birds, mammals).

Examples of animal variety:

Animal Phyla

Classes of vertebrates

Dichotomous Key (ESGC6)

A dichotomous key is a tool that taxonomists often use to classify organisms correctly. It is a form of hierarchical grouping that involves making decisions in a series of steps, from general differences to very specific differences. It is called a dichotomous key because there are always two choices. There is a very specific way to set up a dichotomous key. For instance, one must always move from the general to the specific, and one must always ensure that the two choices in the decision tree are mutually exclusive and jointly exhaustive. Mutually exclusive means that there cannot be overlap between the two options, as this would result in wanting to place an organism in two groups. Jointly exhaustive means that your two options must cover all possibilities, otherwise you won't be able to place an organism in either of the groups.

Identifying arthropods using a dichotomous naming key

Aim

To use a dichotomous key to identify arthropods.

Table of specimens

A	B	C
D	E	F
G	H	I
J	K	L

Instructions

1. Study the organisms in the table of specimens provided to you.
2. Use the dichotomous key to find out to which taxonomic group each of these arthropods belong.
3. Write the letter corresponding to the arthropod, and then your answer.

	Characteristic	Instruction
1a 1b	Arthropod has eight legs Arthropod does not have 8 legs	go 2 (Arachnids) go 4
2a 2b	Arachnid has pedipalp with pincers Arachnid does not have pedipalp with pincers	SCORPION Go 3
3a 3b	Arachnid drinks blood Arachnid does not drink blood	TICK SPIDER
4a 4b	Arthropod has more than 16 legs Arthropod does not have more than 16 legs	Go 9 (Myriapoda) Go 5
5a 5b	Arthropod has 3 pairs of legs Arthropod does not 3 pairs of legs	Go 6 (Insects) CRUSTACEAN
6a 6b	Insect has hardened fore-wings Insect does not have hardened fore-wings	COLEOPTERA Go 7
7a 7b	Insects are social and/ or live in a hive Insects are not social, do not live in a hive	HYMENOPTERA Go 8
8a 8b	Insects does not have a sponge-like proboscis Insects have a sponge-like proboscis	LEPIDOPTERA DIPTERA
9a 9b	Myriapod with one pair of legs per segment Myriapod with two pairs of legs per segment	CENTIPEDE MILLIPEDE