unit 1 introduction to the living world and
TRANSCRIPT
UNIT 1
Introduction to the living world and characteristics of life: organization of life, diversity of life & kingdoms Origin of life: theory of spontaneous generation, theory of panspermia, theory of biochemical evolution, Miller-Urey experiment
The Diversity of Life
Biology is the study of living things
Living things can be divided into six kingdoms
Archaea Bacteria Protista
Fungi Plantae Animalia
What is Life?
Biology is the study of life - but what does it mean to be alive?
1. Complexity
2. Movement
3. Response to stimulation
Fundaments Properties of Life
Five fundamental characteristics1.Cellular organization
2.Energy utilization
3.Homeostasis
4.Growth, development, & reproduction
5.Heredity
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1.Cellular organization
•All living things are composed of one or more cells
•Cells carry out the basic activities of living
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2.Energy utilization
All living things use energy
•Moving, growing, and thinking require energy
Energy is captured from sunlight by plants and algae through photosynthesis
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3.Homeostasis
All living things maintain relatively constant internal conditions
Organisms keep their interior conditions relatively constant even when the environment varies
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4.Growth, development, & reproduction
Bacteria increase in size and simply split in two
Complex multicellular organisms grow by increasing the number of cells and develop by producing different kinds of cells
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5.Heredity
All organisms possess a genetic system based on the replication and duplication of DNA
DNA transmits the characteristics of an organism from parent to offspring
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Living systems show hierarchical organization◦ Cellular level
Atoms, molecules, organelles, cells
Cell is the basic unit of life
◦ Organismal level
Tissues, organs, organ systems
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◦ Populational level
Population – same species living in same area
Community – all populations of different species living in the same area
◦ Ecosystem level – community and physical habitat .
◦ Biosphere
Earth is an ecosystem we call the biosphere
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The hierarchy of classification – Groups :-
Living organisms have been broadly classified into five main kingdoms.
They are :-i) Monera ii) Protista iii) Fungi iv) Plante v)
Animalia Each kingdom has been further classified into smaller
sub - groups at various levels as :-KingdomPhylum (for plants) / Division (for animals) ClassOrderFamilyGenusSpecies
The Five Kingdom classification of living organisms :-
Organisms
EukaryotesProkaryotes
MoneraUnicellular
Protista
With cell wall
Do not perform photosynthesis
Fungi
Able to perform photosynthesis
Plantae
Multicellular
Without cell wall
Animalia
5Kingdoms
They are eukaryotic, unicellular, mostly aquatic
Some have cilia or flagella which help them in moving
The mode of nutrition may be autotrophic or heterotrophic.
Protozoan
Diatoms
They are mostly prokaryotic, unicellular, do not have a definite nucleus
May or may not have cell wall
The mode of nutrition is autotrophic or heterotrophic.
Example of Monera on next slide-
Bacteria
Cyanobacteria
Mycoplasma
These do not contain chlorophyll
They may be saprophytic or parasitic
Cell wall made up of chitin
Agaricus
PlantKingdom
Plant kingdom
PLANT KINGDOM
CRYPTOGAMAE
THALOPHYTA BRYOPHYTA PTERIDOPHYTA
PHANEROGAMAE
GYMNOSPERMAE ANGIOSPERMAE
MONOCOT
DICOT
(i)THALLOPHYTA
The plant body is not differentiated into stem, root and leaves
thallus.
Vascular tissues are absent.
Chara
(ii)BRYOPHYTA embryophytes (land plants) • No true vascular tissue • called 'non-vascular plants'.
Moss
Marchantia
Marchantia (Liverwort)
(iii)Pteridophytes
vascular plants (plants with xylem and phloem) • neither flowers nor seeds, and are hence called
vascular cryptogams.
reproduce and disperse only via spores.
Pteridophytes include horsetails, ferns, club mosses, and quillworts.
PHANEROGAMAE
seeds
make up the majority of the larger plants.
true stem, leaves and roots.
Propagation of the plant takes place with the help of seeds.
Phanerogamae is made into two further divisions.-
(i)Gymnosperms (naked seeded plants)
(ii)Angiosperms (Seed born within a fruit)
(i) GYMNOSPERMAE The gymnosperms are a group of seed-producingplants that includes conifers, cycads, Ginkgo, and Gnetales.
The term "gymnosperm" comes from the Greek word gymnosperms (γυμνόσπερμος), meaning "naked seeds", after the unenclosed condition of their seeds.
Pines Cycas
(ii)ANGIOSPERME
This group constitutes the largest group of plants.
Seeds are produced inside an ovary which later becomes the fruit.
distinctly differentiated into roots, stem and leaves.
Based on the number of cotyledons (seed-leaves) that form the seed this group is divided into:
Monocotyledons
Dicotyledons
Angiosperm, Monocot & Dicot plants
Bud of pink rose
ANIMALIA
PORIFERACOELENTER
ATA
PLATYHELM
I-NTHESNEMATODA ANNELIDA
ARTHROPOD A
MOLLUSCAPROTOCHOR
D-ATAVERTEBRAT
A
PISCES
AMPHIBIA
REPTILA
AVES
MAMMALIA
Animalkingdom
(i)Porifera organisms with holes.
Non-motile animals
pores ,all over the body.
commonly called ‘Sponges’ and mainly found in marine habitats.
(ii)Coelentrata
Two layered body which is radially symmetrical
Aquatic in habitat
Jellyfish
Sea anemone
(iii)PLATYHELMINTHES Simplest triploblastic organisms showing bilateral
symmetry
Mostly parasites in other animals
Body in dorsoventrally flat and leaf-like or ribbon-like with bilateral symmetry
Tape worm
cylindrical body.
bilaterally symmetrical and triploblastic.
They do not have true body cavity.
They are parasitic.
(v)ANNELIDA Occur in moist soil, fresh water and sea
Body is soft and segmented, triploblastic with bilateral symmetry
First animal with the coelom (body cavity)
Body is covered by a non-chintinous cuticle which may have chitinous setae, or parapodia
Reproduction is generally sexual, but some may reproduce asexually by rejuvination i.e, by regrowing broken segments
Example Annelid on next silide-
Earthworm
(vi)Arthropoda (Joint legged)
They have bilaterally symmetrical body.
The body is segmented.
They have an open circulatory system
The body cavity is filled with blood.
They have jointed legs.
Example of Arthropoda on next slide-
Prawn
SpiderScorpion
(vii)Mollusca
bilateral symmetry.
The coelomic cavity is reduced.
They have open circulatory system and kidney like organs
for excretion.
Chiton
Octopus
(viii)Echinodermata(Spiny skinned)
spiny skinned organisms.
free living marine animals.
triploblastic and have coelomic cavity.
water filled tube feet which help in movement.
hard skeleton made of calcium carbonate.
Star fish
Sea urchin
Sea cucumber
(ix)Protochordata
They have bilateral symmetry and are triploblastic.
The have coelomic cavity.
The have a notochord which is a long rod-like structure
along its back to which muscles are attached and help in movement.
Amphioxus
Herdemania
Vertebrates are grouped into five classes.
They are :-
vertebrates
Pisces Amphibia Reptilia Aves Mammilla
Shark
Tuna
Rohu
(ii)Amphibia(Amphibians)
They are found in land and water.
They do not have scales but have mucous glands on their skin.
They are cold blooded and the heart is three chambered.
Respiration is through gills or lungs.
They lay eggs in water.
Example of Amphibia on next slide-
Frog
Toad
Salamander
(iii) Reptilia(Reptiles)
Snake
LizardCrocodile
(iv) Aves(Birds)
warm blooded animals.
four chambered heart.
breathe through lungs.
outer covering of feathers.
two fore limbs are modified into wings for flying.
lay eggs.
Crow
StorkOstrich
(v) Mammalia(Mammals)
warm blooded animals.
four chambered heart.
mammary glands for production of milk to nourish their young ones.
skin has hairs and sweat glands.
Most of them give birth to their young ones.
Some of them lay eggs (like Platypus and Echidna).
INTRODUCTION
Several attempts have been made from time to time to explain
the origin of life on earth.
As a result, there are several theories which offer their own
explanation on the possible mechanism of origin of life.
Following are some of them:
• Theory of Special Creation
• Theory of Spontaneous Generation
• Theory of Biochemical Evolution
• Theory of Panspermia
• All the different forms of life - created by God.
• HINDU CONCEPT :- Lord Brahma- created the living world in one stroke.
• CHRISTIAN & ISLAM BELIEF :- God created this universe, plants, animals and human beings in about six days.
• It has no scientific basis.
THEORY OF SPONTANEOUS GENERATION
Living things originated spontaneously from inanimate objects.
It is also called abiogenesis or biopoesis.
Supporters :- Aristotle
Epicurus
Von Helmont
They believed
Insects arise from dew
Fish & frog from mud
Fly maggots from meat .
• The opposers disproved this theory.
Redi’s experiment
Pasteur’s experiment
•Proposed by Richter in 1865 and supported by Arrhenius.
•Life had come to earth from other planets of the universe, in the
form of resistant spores.
•British astronomers Fred Hoyle and Chandra Wickramasinghe
proposed: •interstellar dust and comets contain organic compounds.
•comets, which are largely made of water-ice, carry bacterial life
across galaxies and protect it from radiation damage along the way.
Credit: Hoover/Journal of Cosmology
Dr. Richard B. Hoover, an astrobiologist
with NASA’s Marshall Space Flight Center
published a paper on March 4, 2011, claiming
to have found fossil evidence for
cyanobacteria in an extremely rare class of
meteorites, called CI1 carbonaceous
chondrites .
.
Coacervates
Microspheres
UREY – MILLER EXPERIMENT