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Natuurwetenskappe

Lewe en lewenswyse

Opvoeders afdeling

Memorandum

Erdwurm:

1. Omdat dit dooie materiaal in die grond indra, die grond los maak (gasse en water kan inkom), as voedsel vir ander diere dien.

2. Omdat die vel vogtig en sag is vir asemhaling. Die liggaam kan dus vinnig uitdroog, en asemhaling kan nie deur ‘n droë vel plaasvind nie.

3. Omdat dit diere soos die erdwurm kan laat vrek. Dan kan die grond hard word en water, gasse en dooie materiaal sal nie meer kan inkom nie: die grond gaan onvrugbaar word.

Leerder afdeling

Inhoud

AKTIWITEIT: Om inligting oor die erdwurm te interpreteer [LU 2.1, LU 2.3]

DIE ERDWURM

Die erdwurm is deel van ‘n groep wat as gesegmenteerde wurms bekend staan.

Dit is belangrik dat jy die erdwurm leer ken, aangesien hierdie diertjie ‘n belangrike rol in die ekosisteem speel.

Kom ons kyk hoe sy liggaam by sy leefwyse aangepas is.

Liggaamsbou

Die erdwurm is ongeveer 150 mm lank en die hele liggaam bestaan uit ringvormige segmente wat elk ongeveer 1 mm dik is.

Aan die voorste punt is daar ‘n mond met ‘n klein lippie waarmee voedsel in die mond ingestoot word. Op die agterste punt is die anus waar voedselreste die liggaam verlaat.

Op al die segmente, behalwe die eerste en laaste, is daar haartjies wat die wurm help om deur die grond te beweeg.

Beweging

Die erdwurm beweeg deurdat spiere in die segmente saamtrek en verslap waardeur die liggaam lank en dun word en dan weer kort en dik. Die haartjies op die segmente skop teen die grond vas en die wurm beweeg vorentoe.

Voeding

Die erdwurm kom in die nag uit die grond uit en trek met die lippie voor sy mond verrottende plantmateriaal in sy tonnel in. Hy vreet ook grond soos hy sy tonneltjies deur die grond grawe.

Asemhaling

Die erdwurm haal deur sy vogtige vel asem. Dit is dus belangrik dat die vel vogtig bly en die wurm is dus afhanklik van ‘n vogtige omgewing.

Handhawing van ‘n waterbalans

Die erdwurm het ‘n ingewikkelde stelsel van buisies in sy liggaam met openinge na buite waarmee hy die hoeveelheid water wat sy liggaam opneem en afgee, beheer sodat die regte balans gehandhaaf word.

Voortplanting

Twee erdwurms lê teenmekaar en ruil geslagselle uit. ‘n Slymkokon vorm om hulle liggame en die geslagselle bly in die kokon agter wanneer dit van die liggaam afskuif. Die kleintjies broei in die kokon uit en lyk onmiddellik nes hul ouers.

Opsommend: die erdwurm in die ekosisteem

1. Die erdwurm speel ‘n belangrike rol in die ekosisteem omdat hy ... (gee twee redes)

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2. Die erdwurm is afhanklik van ‘n vogtige omgewing omdat _________________

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3. As ons gif gebruik om peste te bestry, kan dit die grond benadeel omdat

_____________________________________________________________________

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_____________________________________________________________________

_____________________________________________________________________

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Assessering

Leeruitkomste 2: Die leerder ken, interpreteer en pas wetenskaplike, tegnologiese en omgewingskennis toe.

Assesseringstandaard 2.1: Dit is duidelik wanneer die leerder betekenisvolle inligting onthou: onthou, ten minste, definisies en komplekse feite;

Assesseringstandaard 2.3: Dit is duidelik wanneer die leerder inligting interpreteer: interpreteer inligting deur kernidees in die teks te identifiseer, patrone in aangetekende data te vind en gevolgtrekkings te maak uit inligting in verskeie vorme (bv. prente, diagramme en geskrewe teks).

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
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Devang Reply
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
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SUYASH Reply
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SUYASH
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s. Reply
of graphene you mean?
Ebrahim
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Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
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Cied
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abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
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Porter
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Yasmin
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Cesar
I'm interested in nanotube
Uday
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Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
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Damian
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I'm interested in Nanotube
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this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
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Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
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Source:  OpenStax, Natuurwetenskappe graad 7. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11078/1.1
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