BIOLOGY
NOTES
Grade 12
(AS)
2023
Teachers: Martha Haukena/Emiliana Sheehama
pg. 1 Biology AS Level
,Theme 1: classification of living organism
1.1 classification
Classification is the process of dividing organisms into groups according to their similarities.
Importance of classification
➢ classification helps scientist to identify unknown organisms
➢ it helps to keep track of all organisms
➢ it makes it easier for scientist to communicate internationally
➢ classification make it easier to study living organisms
1.1.1. Use and describe the binomial system of naming organisms.
Binomial system was introduced by Carolus Linnaeus, a Swedish Botanist in the 1700s. He
was regarded as a father of classification
Describe binomial system
➢ Binomial system name living organism by assigning them two-word scientific Latin name.
➢ it is a two-word Latin naming system,
➢ it uses two different words to name species of living organisms,
➢ The two names consist of a generic (a noun), which name the genus of that species and a
specific epithet (an adjective), which indicate the species itself.
➢ The first part of the name(genus) is written starting with a capital letter,
➢ The second name (species) is written staring with the small letter.
➢ When handwritten, the two names should be underlined separately, but when typed, they
should be typed in italics.
Example of how the scientific name for a human being is written using the binomial naming system/
binomial Nomeclature.
Homo sapiens
Genus species
This is how you should write the same name during the exam, when you are unable to type.
Homo sapiens (each name is underlined separately)
Figure 1.1. Magpie species of the world
pg. 2 Biology AS Level
,1.1.2. Describe the use of a hierarchical classification system for living organism.
➢ As an extension to the binomial naming system, Linnaeus originally classified nature into a
hierarchy based on three broad groups, called kingdoms. The three kingdoms were animals,
plants and minerals.
➢ Each kingdom was divided into classes and classes were divided into orders and orders were
divided into genera (singular genus) and then species.
➢ Today, a few extra levels have been added to the hierarchy.
• The broadest level of life, a domain. All living things fit into three domains only
namely, Archaea, Bacteria and Eukarya
• The domains are divided into kingdoms for example eukarya includes kingdom
Animalia, Fungi, Plantae, Monera (prokaryotae) and Protoctista.
• Each Kingdom contains phyla (singular phylum) followed by class, order, family,
genus and then species.
• Each level of classification is called a taxon (plural taxa).
pg. 3 Biology AS Level
, Kingdom
Very general group that contains many organisms
• There are at least five kingdoms- animals, plants, fungi, protoctista (very small organisms)
and monera (bacteria or prokaryotes)
Phylum
• The major phylum within the animals’ kingdom are chordata (animals with backnones),
arthropoda(insects) and molluscs such as snails.
Class
• Each phylum is divided into classes. Classes within the chordata phylum are mammalia
(mammals), reptlilia (reptiles) and osteichthyes (fish), among others.
pg. 4 Biology AS Level
NOTES
Grade 12
(AS)
2023
Teachers: Martha Haukena/Emiliana Sheehama
pg. 1 Biology AS Level
,Theme 1: classification of living organism
1.1 classification
Classification is the process of dividing organisms into groups according to their similarities.
Importance of classification
➢ classification helps scientist to identify unknown organisms
➢ it helps to keep track of all organisms
➢ it makes it easier for scientist to communicate internationally
➢ classification make it easier to study living organisms
1.1.1. Use and describe the binomial system of naming organisms.
Binomial system was introduced by Carolus Linnaeus, a Swedish Botanist in the 1700s. He
was regarded as a father of classification
Describe binomial system
➢ Binomial system name living organism by assigning them two-word scientific Latin name.
➢ it is a two-word Latin naming system,
➢ it uses two different words to name species of living organisms,
➢ The two names consist of a generic (a noun), which name the genus of that species and a
specific epithet (an adjective), which indicate the species itself.
➢ The first part of the name(genus) is written starting with a capital letter,
➢ The second name (species) is written staring with the small letter.
➢ When handwritten, the two names should be underlined separately, but when typed, they
should be typed in italics.
Example of how the scientific name for a human being is written using the binomial naming system/
binomial Nomeclature.
Homo sapiens
Genus species
This is how you should write the same name during the exam, when you are unable to type.
Homo sapiens (each name is underlined separately)
Figure 1.1. Magpie species of the world
pg. 2 Biology AS Level
,1.1.2. Describe the use of a hierarchical classification system for living organism.
➢ As an extension to the binomial naming system, Linnaeus originally classified nature into a
hierarchy based on three broad groups, called kingdoms. The three kingdoms were animals,
plants and minerals.
➢ Each kingdom was divided into classes and classes were divided into orders and orders were
divided into genera (singular genus) and then species.
➢ Today, a few extra levels have been added to the hierarchy.
• The broadest level of life, a domain. All living things fit into three domains only
namely, Archaea, Bacteria and Eukarya
• The domains are divided into kingdoms for example eukarya includes kingdom
Animalia, Fungi, Plantae, Monera (prokaryotae) and Protoctista.
• Each Kingdom contains phyla (singular phylum) followed by class, order, family,
genus and then species.
• Each level of classification is called a taxon (plural taxa).
pg. 3 Biology AS Level
, Kingdom
Very general group that contains many organisms
• There are at least five kingdoms- animals, plants, fungi, protoctista (very small organisms)
and monera (bacteria or prokaryotes)
Phylum
• The major phylum within the animals’ kingdom are chordata (animals with backnones),
arthropoda(insects) and molluscs such as snails.
Class
• Each phylum is divided into classes. Classes within the chordata phylum are mammalia
(mammals), reptlilia (reptiles) and osteichthyes (fish), among others.
pg. 4 Biology AS Level
