€%*YLLABU*Chorocteristics of living things: Need nutrition" respir.e io convert food inlo energy, rnsde up *fcells, respond to stirnuli,- undergo definite chcnges during their life, live for s dJfiniie period cfiime, reproduce more of their kind" Differences between living snd nonliving fhings. Differ*ncesbetween plcnts cnd onirnols.

Children now you can easily distinguishbetween living and non-living things. Forexample, you know that a butterfly, a dogand a plant are living things but a bicycle, ihouse and a stone are not. Things that showcharacteristics of life are called living thingsor living organisms whereas things that donot show characteristics of life ire callednon-living things. All the living and non-living things are made up of molecules.But, they differ in the way the moleculesare affanged. Also, living things show somecharacteristics features that non-living thingsdo not. Let us look at those special featurei,that characterise living things.

BASICCHARACTERTSTICS OFLIVING THINGSLiving things ore mode up ofcellsA house is built of bricks. In the sameway, all living things are made up of cells.

(Biomolecules-molecules present in livingorganisms constitute cells.) A cell is, thus,the basic structural and functional unit ofall living beings.

Fig. 1:1 Dffirent types of cells in a drop of humanblood as seen on magntfying 3000 times

Some organisms like Amoeba, Paramoecium,Euglena and Chlamydomonas are made ofonly a single cell. They are called unicellularorganisms. Other organisms like a dog, a cat,a human being, a tree, and so on areconstituted of a large number of cells. Th.yare called multicellular organisms.

Euglena is o unique orgcnism th i i concccurnui*fs nuirients hy phcfosynthesis ondmove l ike an cnimcl by twistrng itself.

Generally, cells have certain basic featuresin common. For example, all cells have athin outer covering called cell membrane.Inside the cell is a nucleus that controls thefunctions of the cell, and cytoplasm-theliving substance that fills the space aroundthe nucleus. However, the plant and animalcells differ from each olher in certainfeatures. A plant cell has a rigid cell wall inaddition to the cell membrane. An animalcell has no cell wall. Cells of green leavesalso have chlorophyll containing organellescalled chloroplasts, which an animal celldoes not have.

Paramoecium

(c) cFig. 1.2

- Cell membrane

Fig. 1. A generalized cell b\,/

The common elements that make up thebody of a living organism are .uiborr,hydrogen, nitrogen, oxygen, phosphorus,su lphur , ca lc ium, i ron, magnesiurn,potassium and sodium. These elementscombine to form complex compoundswhich together form the livinq mattercalled protoplasm. It is the pr6toplasmthat gives life to all liring organisms. Infact, all biochemical reactions requiredfor the sustenance oi tit-e take plaie inthe protoplasm. Protoplasm is a generalterm for the otoplasrn.

i .

ffi-hlamydomonas

Unicellular organisms

Use a tooihpick or o cottcn bud ta screp orwipe around the inside of your cheek. Dab rhecotton bud or roll the ioofhpick ci the centreof o g lcss s l ide. cet tNow pit o drop o{ ,"iTrur"

c}4oPlasm nucleus

iadine, io moke theceii struciure visibleunder o microscope*nd ccyer it wiihs csver slip. Drowthe structure of thecslis wiih nucleus osy*u see under thern!crcscop*. Figure. 1.3 Cheek cells

TruNx

Living things need food ondnutritionAll living things grow and flourish by takingfood and water from their environment.The process of taking food for survival iscalled nutrition. \,/

Plants absorb water and many mineralsdissolved in the soil. They also take carbondioxide from the air. Water and carbondioxide are used in the preparation of food(carbohydrates) with the help of chlorophyllpresent in the leaves, in presence of sunlight.Thus, plants can make their own food bythe process known as photosynthesis. Sothey are known as autotrophs.

6CO2 + 6H2O Sunlisht

,

Carbon water

oxide

vC6H12O6 + 60,2

Glucose Orygen

However, the mode of nutrition in animals isdifferent from that of green plants. Animalscannot make their own food. Th.y dependon plants for food directly or indirectly. Sothey are known as heterotrophs.

Living things respire to convertfood into energyAll living things respire. During respiration,they take in oxygen from the air and release

carbon dioxidevapour. In the

and some amount of waterprocess, energy is released.

The oxygen which living things take in,reaches to the cells and helps in breakingdown of food. The energy stored in the foodis then released. This energy is utilised fordifferent activities of the body. The breakingdown of food also results in the productionof carbon dioxide and water, which arereleased as waste.

Food + oxygen -> en€rgl + water.runh,+ carbon dioxide

Unicel lular organisms l ike Amoeba,Paramoecium and bacteria do not haveany specific organ for respiration. Instead ofactual process of breathing, oxygen enters intheir bodies by simply diffirsion. However,multicellular organisms have specific organsfor respiration. Man and higher animals like

Toke some limewoter in fwo shollow bowls.Exhole oir into one of them. You will see thstl imewoter turns milky in the bowl in which oiris exholed. This shows thot corbon dioxide isgiven out during respirotion.

Fig. 1.5 Carbon dioxide is released duringresoiration

G//s

cows, horses, dogs and cats respire throughlungs. Fish respire through gills, earthwormsthrough their moist skin, and insects likebutterflies and mosquitoes have special airholes called spiracles for respiration. Plantshave tiny openings called stomata on theirleaves, through which they respire. In plants,gases such as oxygen and carbon dioxidediffuse in through stomata and lenticels.

(a) Human beings respire

(b) Fish respirethrough gills

(c) Plants respire throughsmall pores called stomata

Fig. 1.6 Diferent living organisms respire throughdiferent organs

Liviirrit

things respond to stimuli:ility or sensitivity

Stimulus is an agent that causes a response.Living things respond to external stimulilike light, heat, touch, and so on. Theseresponses take various forms, for example,a snail immediately withdraws within itsshell when it is touched.

Human beings and many animals shiverwhen it is too cold. Plants also react tochanges in their surroundings.

A gentle touch or even the heat from alighted candle or matchstick will make theleaflets of Mimosa (touch-me-not) to droop.

Fig. 1.7 Response to stimuli in Mimosa plant

The rain tree closes its leaves at sunset. Someflowers open in the morning and close atnight. The sunflower always faces towardsthe Sun during the day time.

Fig. 1.8 Sunflower faces the Sun

Living things moveMost living things do not stay at the sameplace. Animals move from place to place forfood, shelter and to escape from predators.This movement is called locomotion. Forexample, a frog hops, a snake crawls, a birdflies, a fish swims and a man walks.

ar

ngob

Movement in plants is, howev€r, different.Plants cannot move from one place toanother as they are fixed to the soil. Butsome of their parts show movement. Stemgrows towards sunlight, roots spread outunder the soil to absorb water and mineralsdissolved in it.

Flowers unfold their petals. Certain lowerplants llke Chlamydomonas, can move inwater.

Living things growAll living things grow. Growth is charac-terised by increase in weight and thesize of their body. It is a permanent andirreversible c.hange. An infant grows intoan adult human, a chick grows into a hen,a calf grows into a cow and a seed growsinto a plant.

Fig. 1.9 Phases of growth in a plant

All life starts from a single cell. The growthof organisms is due to multiplication of cells,resulting in increase in the number of cells.U:ricellular organisms grow by increasingthe size of the cell.

organlsms,such animals,

em{:,

ffimembrane

Lrvrng organlsms, sucn as antmals, stopgrowing after they have attained a certain

Livingcontains glands which excrete common saltand water in the form of sweat.

In plants, the waste products are convertedinto harmless substances, e.g., gums andresins, which can be stored. plants store

#ffiFig. 1.10 A cell dividing into two

Living things excreteAll living things produce waste, whichis poisonous and must be thrown out ofthe body. This process is called excretion.Human beings and animals release carbondioxide and pass stool and urine from thebody every day. Most animals release carbondioxide through their lungs. Also, kidneysin animals filter out nitrogenous waste,excess minerals and water. The human skin

age but flowering plants continue to growthroughout their lives. The banyan tree,peepal tree and mango tree continue to growthroughout their lives.

waste in old leaves or in the bark. plantslose their waste when leaves fall in autumnor when the bark is shed naturally.

Living things live for o definiteperiod of timeAll living things have a definite life cvcle.Th.y are born and they grow into adultsthrough-various phases. And gradually, theygrow old and ultimately die. No living thinglives forever. Each of them has a aennitelife span. The life span varies from animalto animal and plant to plant. Some lives fora short time and some for a long time. Forexample, the life span of the mivflv is 24hours while the tortoise lives for' L20_I50years. Similarly, some plants live for oneyear or one season, and others for a longtime, that is, for 100 years or more.

Organism Life span

Bacteria .................20 minutesMuyfly....... .................24 hoursHousefly... 1-4 monthsBeetle........ 4 monthsMouse.......

Squirre1..... g-9 yearsDo9.. . . . . . . . . . r2-r4 yearsSpider ......20 yearsLion.......... 20-25 yearsHorse........ 25-30 yearsOstrich 45-50 yearsHuman 70-75 yearsElephant... 70-90 yearsTortoise

Life span of some organisms

_-#%_C" Tadpole ru

Fig. 1.11 Lift cycle tfros

Living things reproduce moreof their kindAs you know, every living organism has adefinite life span. To maintain tihe continuitvof their race, all living organisms tend toproduce more of their kind.The process by which living organismsgive birth to their own kindlnd"help inperpetuating their own race is termedreproduction.

#Young 6l #frog

Fe*g

The new individual (offspring) may at first bedifferent in form and size from the parents.As they grow and develop, they begin toresemble parents. Most piants produce seedswhich grow into new plants. However, somecan be propagated by vegetative means. Forexample, stem cuttings of a rose plant can

Spawn*k%

Adult

Fig. 1.12 Polar bear

be used for growing more plants of thesame kind.

Mammals givebirth to youngones. However,reptiles, birds,frogs, fish andinsects lay eggswhich hatchinto young ones.

Living

Living things are made-up of cells.

Need food and nutrition. Th.y use foodand nutrition to obtain energy requiredfor various activities.

Living things respire. Respiration isnecessary to convert food into energy.Th.y release carbon dioxide and someamount of water vapour in the process.Food + Oz -- energy + water vapour + CO2

Living things respond to stimuli, i.e., theycan feel.

Living things can move. Th.y showmovement due to their internal forces.

Living things grow weight and size oftheir body. They undergo definite changesduring their life.

Living things excrete the waste materialsout of their body.

Living things live for a definite period oftime, i.e., a definite life span.

Living things reproduce more of theirkind by reproduction.

Dro You KNow

Non-living

Non-living things are not made-up ofcells.

Fuel and batteries from external sourcesprovide energy.

Do not respire.

Non-living things do not respond tostimuli.

Only move when driven mechanically beexternal sources.

Non-living things do not grow. Th.yremain the same throughout the time oftheir existence.

Do not excrete.

Non-living things have no definite lifespan.

Non-living things are not capable ofreproduction.

\_Differences between living ond non-living things

1.

2.

3.

4.

5.

6.

7.

8.

9.

Differences betweeKplontsPIants

A plant cell has a rigid cell wall.Cells of green leaves have chlorophyllcontaining organelles called chloroplasts.Plants are knownthey make ,r,J J:TTJ:f*becausephotosynthesis.

Plants respire through stomata (tinvopenings) present on the surface oi theirleaves.

An animal cell has no cell wall.An animal cell has no chloroplast.

Animals are known heterotrophs becausetfef ar^e directly or indirec,fy j.p."aent

onplants for food.

Animals mostly respire through lungs, butsome of them alsand moist skin.

o respire through gills

Animals can move from place to place tocafty out different sorts of activities.Animals stop growing after they attain acertain age.

Animals release Carbon dioxide.

ond onimofsAnimals1 .

2.

3.

4.

5.

7.

Plants cannot moveanother as they are

lrom one place tofixed to the soil.

Flowering plants grow throughout theirIives.

Plants release oxygen.

9

l*

\*

rl

*

h|

lr|

I

Things around ur ul: either living or non_living.

fll3::^ints and bacteria ur. iiuing things.

e of their kind to perpetuate their race.

Living organisms are mad. rp "f;t;;"r'#"..tt.0 cells.Living organisms need nutrition. Th.y also need urr, *ur., and food.ytt organisrns respire to release energy stored in food.Living organisms respond to stimuri ,uJ u, h.ut, touch,light and so on.

l*ag organisms move on their own.Living organisms excrete waste products and poisonous substances in the form ofurine, sweat, stool, carbon dioxide and water vapour.

:ilff..[tT,: ttut for a definite period of tim;. Th.y are born, they grow and,

2.

3.

4.

t. Answer the following questions:

(a) How does a snail respond when touched?

(b) What kind of movement is observed in plants?

(c) All living things have a definite life span. Explain.

(d) What are the building blocks of all living things?

(e) Explain why a car and a candle flame are not living.

(f) \fhen do the leaves of Mimosa droop?

Thbulate the differences between Iiving and non-living things in your notebook.

Tabulate the differences between plants and animals in your noteboolc

FiIl in the blanks.

(a) All living things need food and

(b) Animals cannot make their own

(c) Living things are made of

(d) Flowering plants breathe through the ............................... .......present on their leaves.(e) Fish respires through

(f) All cells have a thin outer covering called a

state whether True or False. AIso rewrite the false statements correctly.

(a) Animal cells have a cell wall. -.r

(b) Cockroaches breathe through spiracles.

(c) complex compounds together form the lMng matter called protoplasm.

(d) Growth is characterized,by a decrease in the size of the body.

(e) Cells of animals contain chlorophyll.

(f) Amoeba is a multicellular organism.

(g) The nucleus controls the functions of a cell.

Define.

(a) Reproduction

(c) Protoplasm

(e) Locomotion

(b)

(d)

(f)

Nutrition

Cell

Lenticels

7. Match the following:

, A 1;:q'

re " ::"'i#;

[@t ptant cellsl / L \ 1 , .| \u,, unlcellular organism

6l**' ,r..FaJ rirring beings

Gl s..- cuttingsDraw.

Stomata

Euglena

Animal cell

__ .".P,"*",..,\(i) I chtamydomonas

@ nurr. a life cycle

@ cel wall

@ ,os. plunt

@ .lor., its leaves at sunset

(a)

(b)

(c)