L2 Introducing of Live and Living Things

7/30/2019 L2 Introducing of Live and Living Things

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INTRODUCING TO LIFE AND LIVING THINGS


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Aristotle (384 322 BC)Aristotle (384 322 BC)

Proposed the theory ofProposed the theory ofspontaneous generationspontaneous generation

Also calledAlso called abiogenesisabiogenesis

Idea thatIdea that living things can ariseliving things can arisefrom nonlivingfrom nonliving mattermatter

Idea lasted almostIdea lasted almost 2000 years2000 years


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Spontaneous GenerationSpontaneous Generation

For centuriesFor centuries,, people basedpeople based theirtheirbeliefsbeliefs onon theirtheir

interpretations ofinterpretations ofwhat they sawwhat they saw going on in thegoing on in the

world around them without testing their ideasworld around them without testing their ideas

TheyThey didnt use the scientific methoddidnt use the scientific method to arrive atto arrive at

answers to their questionsanswers to their questions

Their conclusions were based onTheir conclusions were based on untesteduntested

observationsobservations


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Examples of Spontaneous GenerationExamples of Spontaneous Generation

Example #1Example #1

Observation:Observation:Every year in the spring, theEvery year in the spring, the Nile River floodedNile River flooded

areas of Egypt along the river, leaving behind nutrient-rich mudareas of Egypt along the river, leaving behind nutrient-rich mud

that enabled the people to grow that years crop of food.that enabled the people to grow that years crop of food.

However, along with the muddy soil,However, along with the muddy soil, large numbers of frogslarge numbers of frogsappeared that werent around in drier timesappeared that werent around in drier times

Conclusion:Conclusion: It was perfectly obvious to people backIt was perfectly obvious to people back

then thatthen that muddy soil gave rise to the frogsmuddy soil gave rise to the frogs


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What is Biology ?What is Biology ?

The study of Living Things

Bio = life

logy = knowledge


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How to Study Biology ?How to Study Biology ?

So many new words !

know some common prefix and suffix

e.g.. photosynthesisphoto = light

synthesis = to combine together

to combine some elements together

by using the energy from sunlight


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Basic characteristics of living thingsBasic characteristics of living things

NutritionNutrition

Take food for energy,Take food for energy,growth and repairgrowth and repair


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RespirationRespiration

Gaseous exchange

(breathing)

Oxidation of food to

produce energy


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ExcretionExcretion

Removal of

metabolic wastes

(not faeces)



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GrowthGrowth

Increase in size

and complexity



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ReproductionReproduction

Produce babies of the same species



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IrritabilityIrritability

Respond to stimuli



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MovementMovement

Animals: Wholeorganism moves

from place to place

Plants: Only part of

its organ can move

about



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Life is tenacious, and it completely

permeates the surface layer of theplanet.

We find life beneath the deepest

ocean, onthe highest mountain, in the driest

desert

and the coldest glacier, and deep downin

the crystal rocks and sediments. Not

knowing what conditions are needed

for the


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The Big Bang


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How life began

Our planet earth, soon after it was formed some4500 million

years ago, now seems like an alien world where noliving

thing could survive. The earths atmosphere

comprised of: Little or no oxygen

Toxic gases like carbon monoxide, methane andammonia, together with nitrogen and hydrogen.

These above and dense clouds of water vapourwere blasted into the sky from numerous activevolcanoes and hot springs.

The world was also exposed to UV light and

intense heat from the sun, flashes of lightningduring frequent violent thunderstorms, and


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The Miller Experiment

When scientists set about solving the problem of how lifebegan,

they first looked for a source of the chemicals out of whichliving

things are made. They devised a theory, that under theprimitive

Earths conditions, the complex chemicals of life couldform from

simple, inorganic precursors. In 1953, Stanley Miller testedthe

theory:

Miller essentially put methane, or natural gas,ammonia, hydrogen gas, and water vapour into abeaker, based on the theory of what the primordialatmosphere would have looked like.

Next, he simply put an electric charge through that


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On analysis of the vessel, rather than only having

methane and ammonia, he actually had amino acids,which are the building blocks of proteins, fatty acidsand other complex biological molecules.

So the chemistry that Miller was discovering in this

wonderful experiment was not some improbablechemistry, but a chemistry that is widely distributedthroughout our solar system.

The experiment used water (H2

O), methane (CH4

),

ammonia (NH3) and hydrogen (H

2).

The chemicals were all sealed inside a sterile array ofglass tubes and flasks connected together in a loop,

with one flask half-full of liquid water and another flaskcontaining a pair of electrodes.


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The liquid water was heated to induce evaporation, sparkswere fired between the electrodes to simulate lightningthrough the atmosphere and water vapour, and then theatmosphere was cooled again so that the water couldcondense and trickle back into the first flask in a continuouscycle.


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Lifes Beginnings These chemicals of life accumulated in lakes and ponds,

where they changed, combined, and re-combined inmillions of different ways over vast periods of time.

Complexity increased until cell like structures appearedwith the first major characteristics of life: the ability to

reproduce and grow, feeding on materials from theprimordial soup in which they formed.

About a thousand million years later, cells appeared whichchanged the course of evolution. They developed thegreen pigment chlorophyll, which enabled them to use

sunlight energy to make food from water and carbondioxide, releasing oxygen into the Earths atmosphere forthe first time.

These, the first plants gave rise to the Plant Kingdom weknow today. They not only maintain an oxygen rich

atmosphere, but make the food upon which all other lifede ends.


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things

It is not always an easy thing to tell the difference between living,dead, and non-living things There a few set of rules which arefollowed by scientists to classify something as living:

Living things are made of cells.

Living things obtain and use energy

Living things grow and develop

Living things reproduce

Living things respond to their environment

Living things adapt to their environment

Examples of living things: Dogs, Cockroaches, Plants, YOU.

Examples of non living things: Stones, wood, water, fire.


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Looking more closely: Living things move and have senses: Animals walk, run, hop,

swim, crawl or fly. They find their way using sense organs eyes, ears, noses, taste buds, skin and insect feelers calledantennae.

Plants move by growing. They do not have sense organs but

respond to the environment roots show positive geotropism,and hydrotropism as they grow downwards in response togravity and water, and shoots show positive phototropism inresponse to water.

Living things feed:

Plants make their own food in their leaves by a process called

photosynthesis.

Carbon dioxide + Water Glucose + Oxygen

Animals cannot make their own food, and hence, they rely on

plants, and/or other animals for their source of food.

sunlightchloroph

yll


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Living things respire:

They get energy from food by a process called respiration. This

usually needs oxygen.

Food + Oxygen ENERGY + Waste (Water +Carbon Dioxide)

Living things excrete:

All living things produce waste. The removal of waste from theirbodies is called excretion. Animals excrete through theirlungs and kidneys, and through their skin, when they sweat.Plants store waste in old leaves, which fall in the autumn.

Living things reproduce and grow:

Animals lay eggs, or have babies, whereas seeds from plantsgrow into new plants.

Animals stop growing when they reach their adult size. Plants

grow all their lives.


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Needs of living thingsWhat do you need to live comfortably? The listprobably includes food, a home, clothes,

and water. But, the basic necessities ofevery living thing includes:

Light and Carbon Dioxide:

All life forms need energy to survive. Livingthings use energy to grow, to defendthemselves, and to move around thisenergy is provided by the Sun the primarysource of energy.

Plants use sunlight and carbon dioxide from theair to create their own food byphotosynthesis.

Many animals then eat the plants, taking thisenergy into their own bodies. Other animalsthen eat these plant eaters, passing theSun's energy from one organism to another.

The food organisms take in provides them withenergy, and also provides them with the

resources, and raw materials they need tobuild up their bodies, grow, and repair

The amount of energy

in all the coal, and oil

reserves on Earth is

equal to only 20 days

of sunlight that reaches

the Earth.


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Water:

> Living things need water to survive.

But why is water so important? Alllife forms on Earth are comprisedalmost entirely of water. Your ownbody is about 66% water.

> Water in your blood helps transport

food, and chemicals to your cells. Ithelps remove waste products fromyour body. Water is used to cool youdown, to warm you up, and to carryout the chemical reactions thatallow you to move and grow.Another important use of water, isto keep your body clean.

> Plants use water to grow, to transportfood, and to carry out chemicalreactions. In addition, plants usewater as part of photosynthesis, tocreate their own food.


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Oxygen:

Without food, your body would die in a matter of weeks.

Without water, you would day in days. How long do youthink you would live without oxygen?

Most life forms use oxygen as the main ingredient in manyof the chemical reactions needed for life.

Organisms get oxygen from their environment in a varietyof ways. Many land animals breath oxygen directly

from the air, while ocean bearing animals often use theoxygen dissolved in the water to survive.

Minerals:

The Earths soil contains minerals, which are essential forhealth and growth. Plants take in minerals through

their roots. Animals get minerals by eating plantsand/or other animals.

Warmth:

If it gets too hot or cold, the chemical changes which arenecessary for life will stop. In many parts of the Earth,temperatures lie between 25deg Celsius and 30degCelsius. Most living things are adapted to live at these


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The biosphere:

> Biosphere is all those parts of theearths surface where livingthings are found. All of theneeds we have mentioned sofar, energy, food, water, andoxygen are obtained by

organisms in their environment,or the space around them.

> The amount of resources found inan environment are oftenlimited. There is only a certainamount of food, to be found.There may not be enough water,for all to drink. For this reason,living things need space.

> Living things are found almosteverywhere, from about 9000

metres up mountains to at least


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Cells

The cell is the structural and functional unit of all knownliving organisms. It is the smallest unit of an organism that isclassified as living, and is sometimes called the building blockof life.

Our skin, muscles, brain are all made of cells.

Humans have an estimated 100 trillion cells.

The largest known cell is an ostrich egg.

INSIDE AN ANIMAL CELL:

Cell membrane semi permeable protection around the cell.

Cytoplasm Jelly-like substance, containing hundreds ofchemicals, where lots of chemicals reactions take place. Itfills the cell.

Nucleus it controls what a cell does, and how it develops.

Vacuole this is a space within the cell containing air, liquids,or food particles. Animals cells usually have several small

vacuoles.


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Cells are not all the same shape. There are about 20 differentcells in our bodies, which are specialised to do different

jobs. Red blood cells Disc shaped and their job is to carry oxygen

round the body. White blood cells They can change their shape as they

attack germs. They provide immunity and fight againstdiseases.

Nerve cells Have long thin fibres, which carry nerveimpulses messages around the body.

INSIDE A PLANT CELL: Cell wall Made of cellulose. It covers the cell membrane. Cell Membrane Semi permeable protection around the cell. Cytoplasm - Jelly-like substance, containing hundreds of

chemicals, where lots of chemicals reactions take place. Itfills the cell.

Vacuole present in all plant cells. Contains liquid called cellsap.

Chloroplasts tiny discs full of green substance calledchlorophyll. They trap the light energy that plants need to


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Cell

STRUCTURE OF A PLANT CELL


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L2 Introducing of Live and Living Things