Leaving Certificate Biology

8/14/2019 Leaving Certificate Biology

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Amoeba

Leaving Certificate Biology

H. Jones, St. Columbas College


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Amoeba


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Characteristics of ProtistaContains single-celled and simple multi-cellular organisms

They are eukaryotic they have a membrane-enclosednucleus and membrane enclosed organelles

Some feed by taking in organic substances, others can

photosynthesise.Include:Amoeba moves by means of pseudopods and is well known

as a representative unicellular organism.Algae a large and diverse group of plant like organisms

ranging from unicellular to multicellular formsParamecium consist of a single cell yet are visible to thenaked eye


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AmoebaConsists of a single cell

It is a consumer. It feeds on small plants, animals and bacteria

It lives in freshwater ponds (most likely to be found on themud at the bottom)


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CytoplasmEctoplasm

Endoplasm

Nucleus

Pseudopod

Contractile Vacuole

Food Vacuole

Fat Droplets

Waste products

Structure of AmoebaCell membrane


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Endoplasm andEctoplasm

The endoplasm is fluid-like. It has a grainyappearance due to thepresence of food

vacuoles and wastematerials

Ectoplasm can becomesoft in places to allowthe development of

pseudopodia

EndoplasmEctoplasm


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Development ofPseudopod

Pseudopods arereferred to as falsefeet as they areproduced at any point

on the body and haveno fixed position

Pseudopodia extend inthe direction Amoebawishes to move


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Development ofPseudopod

Pseudopods developwhen the ectoplasmsoftens and moves

forward and theendoplasm moves into replace it

Amoeba uses

pseudopodia toengulf its prey


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Endoplasm and

ectoplasm

Before After


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Food vacuoles Amoeba feeds by

surrounding its preywith pseudopodia andsecreting digestiveenzymes into thevacuole created

Food can then be

stored within thevacuole.

Food vacuole


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Food vacuoles


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The Contractile Vacuole

High

sugar/saltconcentration

Low sugar/salt

concentration

Amoebas

cytoplasm is moreconcentrated than

the surrounding

fresh water


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As a result water

constantly rushes in

by osmosis


High

sugar/saltconcentration

Low sugar/salt

concentration


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In order to deal with

this uptake of waterAmoeba forms a

contractile vacuole

Excess waterenters the

contractile vacuole



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The contractile

vacuole swells with

water and moves to

the edge of thecell



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The contractile

vacuole swells with

water and moves to

the edge of thecell



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The contractile

vacuole swells with

water and moves to

the edge of thecell



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Where it bursts

and expels the

water



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Where it bursts

and expels the

water



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Where it bursts

and expels the

water



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Where it bursts

and expels the

water



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The cycle is thenrepeated



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Contractile vacuoleThe contractile vacuole is said to be

responsible for osmoregulation

Without it the Amoeba would expand and

burst

Contractile vacuole


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Contractile vacuolebursting

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