unit 1 introduction to the living world and

Post on 09-Feb-2022

1 Views

Category:

Documents

0 Downloads

Preview:

Click to see full reader

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

4

1.Cellular organization

•All living things are composed of one or more cells

•Cells carry out the basic activities of living

5

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

6

3.Homeostasis

All living things maintain relatively constant internal conditions

Organisms keep their interior conditions relatively constant even when the environment varies

7

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

8

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

9

Living systems show hierarchical organization◦ Cellular level

Atoms, molecules, organelles, cells

Cell is the basic unit of life

◦ Organismal level

Tissues, organs, organ systems

10

◦ 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

11

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

top related