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Natuurwetenskappe

Graad 8

Biodiversiteit: aanpassings en oorlewing

Module 29

Volhoubaarheid

In die vorige leereenhede het ons gekyk na organismes se oorlewingstrategieë op planeet AARDE .

Ons weet ook dat die organismes in hul habitatte saam die aarde se verskeidenheid (biodiversiteit) uitmaak en dat die natuur op sy eie as gevolg van hierdie BIODIVERSITEIT in perfekte balans is.

Daar is byvoorbeeld 250 000 hoër plantspesies, 19 000 visspesies en 10 000 spesies reptiele. Heelwat meer insekspesies is aangeteken. Hierdie rykdom aan lewe sorg vir :

  • ’n atmosfeer met die regte samestelling en balans vir ons om te kan lewe;
  • grond wat vrugbaar bly sodat daar altyd nuwe plante en dus kos vir ons en ander diere sal wees;
  • die hersirkulering van water.

Suid-Afrika is die enigste land op aarde wat ’n hele plantkoninkryk in sy grense het, nl. fynbos in die Wes-Kaap.

Ons in Suid-Afrika is gelukkig om ’n besonder ryk verskeidenheid aan plante en diere in ons land te hê. Is ons werklik bewus van ons rykdom?

BIODIVERSITEIT ONDERSTEUN VOLHOUBAARHEID!!

Die mens is egter aan die stuur van sake en doen nie altyd die regte ding nie.

Aktiwiteit 1:

Om ‘n standpunt teenoor die behoud van biodiversiteit in die natuur in te neem

Bespreek die volgende vraag in die klas:

  • Is die mens deel van ’n natuurlike ekosisteem of is hy ’n ongewenste gas wat inmeng en die balans versteur?

Skryf in jou eie woorde die uitkoms van die gesprek neer (die oorwegende mening van die groep).

[LU 3.2]

Die mens word dikwels daarvan beskuldig dat hy die natuur se hulpbronne vir sy eie selfsugtige behoeftes tap.

As vandag ’n tipiese dag op planeet Aarde is, sal teen vanaand 336 km² tropiese woud verwoes wees om hout te verskaf en plek te maak vir paaie, plase en plantasies. ’n Totaal van 112 km² sal in ’n woestyn verander as gevolg van oorbeweiding of swak boerderypraktyke.

Daar sal ook een en ’n half miljoen metrieke ton gevaarlike afval in die omgewing gestort word. Volgens verskeie skattings sal 50 tot 100 plant- en dierspesies eersdaags uitsterf.

Aan die einde van die dag sal die wêreld ’n klein bietjie warmer, die reën ’n klein bietjie suurder en die aarde se lewensweb ’n bietjie meer verskeurd en gehawend wees. (Chiras, 1993)

Wetenskaplikes waarsku ons teen die mensdom se vernietigende neigings. Die idee van VOLHOUBAARHEID sê dat die mens en die natuur in ’n wen-wen verhouding kan verkeer. Uit die onlangse wêreldkonferensie in Johannesburg, het dit duidelik geblyk dat baie mense glo dat ons met die regte BESTUURSTELSELS en die regte INGESTELDHEID ’n positiewe toekoms vir die hele wêreld kan verseker.

Aktiwiteit 2:

Om na te dink oor die volhoubaarheid van die aarde se bronne

1. Maak ’n lys van al die foute wat die mens besig is om te maak

2. Wat dink jy beteken die term VOLHOUBAARHEID?

3. Noem DRIE natuurlike hulpbronne wat tans deur die mens oorbenut word.

4. Gee die betekenis van Mahatma Gandhi se woorde in jou eie woorde:

"The world contains enough for everyone's need, but not for everyone's greed."

5. Waarom sal ons ernstig moet besin oor die roete wat die mens tans loop?

Belangrike terme is dus:

  • HABITAT : spesifieke plek waar organisme woon
  • BIODIVERSITEIT : die verskeidenheid lewe op aarde
  • HULPBRONNE : alles wat ons in ons voortbestaan gebruik

Aktiwiteit 3:

Om ‘n voorspelling oor die toekoms van die aarde te waag

Die aarde is soos ’n ruimteskip – al sy voorrade is reeds aan hom voorsien en nou moet hy sy reis voortsit – selfvoorsienend!!

Maak ’n A4-plakkaat om jou beeld van die aarde as ’n ruimteskip voor te stel.

Assessering van VOLHOUBAARHEID:

Kon jy die vrae beantwoord en ’n goeie voorstelling van die aarde op jou plakkaat maak?

[LU 3.2]

Assessering

LU 3

Wetenskap, die Gemeenskap en die Omgewing

Die leerder is in staat om begrip van die onderlinge verband tussen wetenskap en tegnologie, die samelewing en die omgewing te toon.

Dit is bewys as die leerder:

3.1 wetenskap as ‘n menslike aktiwiteit kan verstaan;

3.2 volhoubare gebruik van die aarde se hulpbronne verstaan.

Memorandum

Volhoubaarheid

Aktiwiteit 2: leesvaardigheid

  • Gee opdrag - stillees

Aktiwiteit 3: plakkaat- ruimteskip aarde

  • Die aarde is soos 'n ruimteskip – al sy voordae is reeds aan hom voorsien en nou moet hy sy reis voorsit – selfvoorsienend!!
  • Maak 'n A4-plakkaat om jou beeld van die aarde soos wat ruimteskip aarde tans daaruit sien.

Questions & Answers

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
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salma
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virgelyn Reply
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Abhi
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kinnecy Reply
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Jeffrey Reply
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ninjadapaul
20/(×-6^2)
Salomon
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ninjadapaul
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ninjadapaul
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
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Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
ninjadapaul
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ninjadapaul
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ninjadapaul
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or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
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Differences Between Laspeyres and Paasche Indices
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No. 7x -4y is simplified from 4x + (3y + 3x) -7y
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I start with an easy one. carbon nanotubes woven into a long filament like a string
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Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
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AMJAD
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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
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Prasenjit
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Azam
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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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the Beer law works very well for dilute solutions but fails for very high concentrations. why?
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Source:  OpenStax, Natuurwetenskappe graad 8. OpenStax CNX. Sep 12, 2009 Download for free at http://cnx.org/content/col11049/1.1
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