CHAPTER 2
GENERAL VARIETY OF ORGANISMS
2.1 The Diversity of Organisms
1.
2.
There are a large variety of living things in the world.
There are about 1,000,000 different kinds (species) of
animals and 500,000 different plants.
2.2 Classification
1.
Classifying organisms can help us to identify and study
them.
2.
The plan of classification is based on the similarities
and differences in their external and internal features
among the living organisms.
3. Simple classification :
a. The animals in Animal Kingdom can be divided into 2
large groups :
Invertebrates: animals without backbones.
Vertebrates: animals with backbones.
b. The plants in Plant Kingdom can be divided into 2
large groups :
Non-flowering plants : plants without flowers.
Flowering plants : plants with flowers.
3.
Scientific classification:
Kingdom --> Phylum --> ......... --> Genus --> Species
4.
A species is a type of organisms which are
a. similar to each other;
b. can
breed
among
themselves
to
produce
offspring.
fertile
2.3 Different Plant and Animal Groups
1.
The seven characteristics of living things are nutrition,
respiration, excretion, movement, irritability, growth and
reproduction. They are also made up of cells.
matter
non-living things
living-things
plants
animals
2. General differences between plants and animals
nutrition
excretion
growth
response
movement
3.
Plants
by photosynthesis
no definite
excretory organ
1. at special
regions such as
stem tips, root
tips and
cambium.
2. grow throughout
their live
slow
restricted to some
parts of the
plants
Animals
feed on organic
food
has special
excretory organ
1. grow evenly
throughout the
body
2. stop growing
when mature
fast
can move from
place to place
General classification of animals
animals
invertebrates
fish
4.
vertebrates
amphibians
reptiles
General classification of plants :
birds
mammals
plants
flowering plants
dicotyledons
non-flowering plants
monocotyledons
gymnosperms
ferns
mosses
algae
fungi
2.4 Characteristics of the Animal Groups
1. Invertebrates -- animals without a backbone.
e.g. single-cell animals, jelly-fish, coral,
earthworm, insect, shrimp, crab, snail,
clams, octopus, starfish, etc.
2. Vertebrates -- animals with a backbone.
a. fish -------
aquatic vertebrates with moist scales on the
skin;
breathing by gill;
with fins;
body temperature changes with the environment.
external fertilization
e.g. carp, shark, (all fish)
b. amphibian
---
vertebrates with moist skin;
with aquatic larva stage breathing with
gills.
-- Adult may live on land and breathe with
lungs, skin and mouth cavity.
-- body
temperature
changes
with
environment.
-- external fertilization
-- e.g. frog, toad
c. reptile
------
d. bird ----
vertebrates with feather on skin;
the fore-limbs modified into wings;
body
temperature
does
not
change
environment
internal fertilization
e.g. hens, eagle, (all birds)
--e. mammal
------
3.
vertebrates with dry, scaly skin;
breathe by lungs, egg-laying.
body temperature changes with environment;
internal fertilization
e.g. snake, crocodile, tortoise
vertebrates with hair on skin;
mother has mammary glands;
body
temperature
not
change
environment
internal fertilization
e.g. rat, monkey, man, bat, whale
with
with
Summary of vertebrates
Fish
Amphibian
Reptile
Birds
Body covering
Breathing
structure
Body
temperature
Fertilization
Other special
features.
2.5 Characteristics of the Plant Groups
Mammals
1. Fungi (singular : fungus)
a. simple plants without root, stem and leaf.
b. do
not
have
chlorophyll
and
cannot
photosynthesis.
c. live either saprophytic or parasitic.
d. e.g. bread mould, yeast, mushroom
carry
2. Algae (singular : alga)
a. simple plants without root, stem and leaf.
b. with
chlorophyll
(or
other
pigments)
photosynthesis.
c. e.g. spirogyra
out
for
3. Mosses
a. simple plants with simple leaves and stems but no true
roots.
b. usually grow in moist and damp places.
4. Ferns
a. plants with true leaves, stems and roots.
b. have vascular tissues for transporting materials
c. no flower, reproduce by spores.
5.
Gymnosperms
a. plants with true leaves, stems and roots.
b. have vascular tissues for transporting materials
c. no flower, naked seeds produced in cones.
d. the leaves are usually needle-shaped.
e. e.g. pine, cypresses (柏), fir (杉), etc.
6.
Flowering Plants
a. plants with true leaves, stems and roots.
b. have vascular tissues for transporting materials.
c. with flower.
d. There are two main types:
(i) Dicotyledonous plants
-- leaves with net-venation
-- e.g. rose, Bauhinia, broad bean, mungo bean.
(ii) Monocotyledonous plants
-- leaves with parallel venation.
-- e.g. grass, rice, orchid (蘭花), gladiolus (劍蘭)
7.
Summary
Fungi
Algae
Mosses
Ferns
Gymnosperm Flowering
plants
chlorophyll
root, stem
and leaf
vascular
bundle
seed
flower
2.6 Use of keys
1.
Keys can help us to name an organism.
2.
A dichotomous key provides a way to identify organisms by
choosing between two alternative features at each stage of
the key.
3.
A dichotomous key for classification of plants:
1.
plants with flowers
plants without flowers
go to 2
go to 3
2.
leaves with network veins
leaves with parallel veins
dicot plant
monocot plant
3.
have true roots, stems and leaves
no true roots, stems and leaves
go to 4
go to 5
4.
have seeds
do not have seeds
gymnosperms
fern
5.
have simple "stems" and "leaves"
no such simple "stems" and "leaves"
mosses
go to 6
6.
with chlorophyll
without chlorophyll
algae
fungi
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Important words
diversity of organisms
classification of organisms
plants
backbone
fish
reptiles
mammals
monocotyledonous plants
fungi
mosses
gymnosperms
dichotomous key
habitat
animals
invertebrates
vertebrates
amphibians
birds
non-flowering plants
dicotyledonous plants
algae
ferns
key
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Checklist
After studying this chapter, you should be able to
1.
point out that there is a large variety of living things.
2.
classify animals into vertebrates and invertebrates.
3.
classify vertebrates
birds and mammals.
4.
classify plants into flowering and non-flowering plants
using external features.
5.
classify non-flowering plants into algae, fungi, mosses,
ferns and gymnosperms.
6.
use a dichotomous key for identification.
into
fishes,
amphibians,
reptiles,
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