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● Biology is the science of life. Its name derives from
the Greek words "bios" (life) and "logos" (study).
● Biologists study the structure, function, growth,
origin, evolution and distribution of living organisms.
● The study of life and all living organisms along with
their characteristics, environment and evolution

Characteristics of living organisms
Living organisms have the following characteristics in common:
● Movement - they can move and change their position.
● Reproduction – they can make more of the same kind of
organism as themselves.
● Sensitivity – they can detect or sense stimuli and respond to
them.
● Growth - they can permanently increase their size or dry mass
by increasing the number or size of their cells.
● Respiration – they can create chemical reactions that break
down nutrient molecules in living cells to release energy.
● Excretion – they can excrete toxic materials, waste products of
metabolism, and excess substances
● Nutrition - they can take in and absorb nutrients such as organic
substances and mineral ions. These nutrients contain the raw
materials or energy needed for growth and tissue repair.

The Binomial System
The Binomial System of scientifically naming
organisms was developed by Carolus Linnaeus of
Sweden. It consists of the organism’s Genus and
species name, and thus it is called as Binomial. It
consists of 7 levels:
Kingdom
Phylum
Class
Order
Family
Genus
Species

Now, let’s take up a simple example:
Humans
Kingdom- Animal
Phylum- Vertebrates
Class- Mammalia
Order- Primate
Family- Hominidae
Genus- Homo
Species- Sapiens

Key definitions
A species is a group of organisms that can reproduce to
produce fertile offspring.
The binomial systemis an internationally agreed system in
which the scientific name of an organism is made up of
two parts showing the genus and the species
Rules for writing scientific names:
The first letter of the genus is ALWAYS capitalised
e.g. Homo sapiens
The first letter of the species is NEVER capitalised
Scientific names of organisms are always italicized or underlined

The classification of living organisms

● Protoctista: are organisms with a nucleus, and
many flexible organelles amongst their species
(for example, some have chloroplasts and cell
walls like plants and some like animal cells
without these distinguishing characteristics).
Their main characteristics include:
●
● unicellular or multi-cellular bodies
● cells with or without cell wall and chloroplasts
● some species are autotrophic, rest are
heterotrophic
● all species have cells with nucleus

● Fungi: are organisms which do not have
chlorophyll, thus are heterotrophic and feed on
dead organic matter parasitically. The most
common known is the edible mushroom; others
include fungi causing diseases like athlete’s
foot, ringworm etc. Their characteristics include:
● Multicellular bodies (very few are unicellular)
● Have nuclei
● Reproduce by spore production
● Are heterotrophic
● Don’t have chloroplasts
● Feed by parasitic or saprophytic means on
organic dead matter

● The Plant Kingdom
●
● Phylum Angiosperm:
● Have root, stem and leaves
● Have xylem and phloem
● Reproduce by seed production
● Seeds are produced inside the ovary of the
flower
● Phloem: Transports sugar
● Xylem: Transports water and minerals

Viruses
is a small infectious agent that replicates only inside the living cells
of other organisms. Viruses can infect all types of life forms, from
animals and plants to microorganisms, including bacteria and
archaea.
Entirely microscopic
Consisting of a single nucleic acid surrounded by a protein coat
Capable of replication only within living cells of bacteria, animals or
plants.
Example of Viruses: Human Immunodeficiency Virus, Tuberculosis,
etc.
Prokaryotes
Bacteria are prokaryotic and unicellular. they have cell walls and
circular DNA called plasmids. They are Heterotrophs or Autotrophs.
Example: L.bulgaricus

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IGCSE Biology 0610 - Introduction to Biology - Characteristics of living organisms - Binomial Nomenclature - Kingdoms

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IGCSE Biology 0610 - Introduction to Biology - Characteristics of living organisms - Binomial Nomenclature - Kingdoms