Junior 3 Biology
Chapter 1
Characteristics and
classification of living
organisms
Prepared by:
Ms. Wong Yao Wen
By: wyw
How do you define living organisms?
Characteristics of living organisms
(MRS. GREN)
1. Movement
2. Respiration
3. Sensitivity
4. Growth and development
5. Reproduction
6. Excretion
7. Nutrition
1) Movement
• An action by an organism or part of an organism
causing a change of position or place
2) Respiration
• Chemical reactions that break down nutrient
molecules in living cells to release energy for
metabolism
3) Sensitivity
• The ability to detect or and
respond
to
changes
(stimuli) in the internal or
external environment
4) Growth and development
• Growth is a permanent increase in
size and dry mass
• Development makes an organism
become more complex and change
in form
5) Reproduction
• Processes that make more of the same kind of
organism (new individuals!
6) Excretion
• Removal from organisms of:
a) Waste products of metabolism
b) Substances in excess of
requirements
7) Nutrition
• The taking in of materials for energy,
growth and development
How to differentiate living things and non-living
things?
Eg. Both a cat and a motorcar can move.
All characteristics of living organisms need to be
considered.
Test yourself:
List out all the characteristics of living organisms
1.
2.
3.
4.
5.
6.
7.
• There are millions of species of organisms on Earth
1) Species
• as a group of organisms that can reproduce to produce
fertile offspring
2) Classification of living organisms
• Living organisms are classified based on the features
that they share.
• e.g. all mammals have bodies covered in hair, feed young
from mammary glands and have external ears (pinnas)
3) Linnaeus’s system of classification
King Phillip Come Over For Good Spaghetti
Hierarchy of classification
• Provide information on
evolutionary relationships
among organisms
• Similar
characteristics
suggest that organisms
descended from the same
ancestor
4) How to name an organism?
• Binomial system of nomenclature introduced by Carolus
Linnaeus
• Worldwide convention among scientist
• Binomial=‘two name’
• This system gave every organism a two-part name
• Take the final two group names (genus and species)
• Write in Italics or underline
• Example: Panthera leo or Panthera leo
What is the scientific name of these living organisms?
Why do you need scientific names?
5) Classification keys
• How to place organisms into groups?
Ask questions about their characteristics based on
morphology and anatomy that are easily observed and
measured
• Example: ‘Does the organism photosynthesise?’
• Classification key= a series of questions about the
characteristics of organisms
Dichotomous key: with only two answer to each question
Branching form
Listed form
6) Other methods to classify organisms
• New species today may be classified
based on characteristics such as
a) protein structure
b) chromosome number
c) Base sequence of DNA
7) Sequences of bases in DNA helps in
classification
• closely related organisms/ organisms that share a more
recent ancestor have very similar base sequence in DNA
• examples: human and chimpanzees share 98.6% similarities
1) Five Kingdoms
• Living organisms are grouped into five kingdoms using the
keys
• These groups are distinguished from one another by obvious
characteristics of morphology and anatomy
Prokaryote
2) Viruses
• No place could be found in five kingdom system
• Because viruses do not show typical features of living things
(respiration, nutrition and reproduction) unless they are
inside the cells of another living organisms
Structure of a virus
Prokaryote
3) Plants
• Plant kingdom can be divided into several groups, including:
a) Flowering plants/ Angiosperms:
• Have roots, stems, leaves
• Produce flowers and seeds
• Reproduce by seeds
b) Ferns:
• Spore –producing plants
• Have roots, stems, leaves
• Reproduce by spores
4) Two groups of Flowering plants
• Monocotyledons: single cotyledon in seed
• Dicotyledons: two cotyledons in seed
Corn
(monocot)
Peanut (dicot)
a) Number of
cotyledons
Monocotyledons
Dicotyledons
one
two
b) Leaf veins
Monocotyledons
Dicotyledons
Parallel veins
Branched veins
Monocotyledons
c)
Arrangement
of vascular
bundle
Dicotyledons
Monocotyledons
d) Flowers
Dicotyledons
Monocotyledons
d) Roots
Dicotyledons
DICOTS
Prokaryote
Animals
Vertebrates
Animals with backbone
Invertebrates
Animals without backbone
Animals are divided into two groups based on the
presence of backbone.
5) Invertebrates
Nematodes
Annelids
Molluscs
Arthropods
6) Arthropods
• Segmented bodies
• Jointed limbs
• exoskeleton
a) Crustacea
• Example: crab, prawn, lobster
Gills of crustaceans
Two pairs of antennae
b) Myriapods
• Examples: centipede, millipede
c) Insects
• Examples: housefly, mosquito
Antennae
Compound eyes
(wider view angle, less resolution)
d) Arachnids
• Examples: spider, scorpions, ticks
Spinnerets
7) Vertebrates
Fish
Amphibians Reptiles
Birds
Mammals
a. Fish
b. Amphibians
c. Reptiles
d. Birds
e. Mammals
Summary: