Q&A - PSLE Science

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charsen:

ms_lim:

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Is Plant --> Arctic Fox considered as a food chain or a food chain needs to have at least 3 links?

Hi
No.First,ask yourself what is a food chain.A food chain shows a prey and predator relation ship.In this case,the plant is not a prey of the artic fox as the artic fox does not have to hunt for it.Therefore,that is not considered a food chain.A food chain must have at least one plant,one herbivore and one carnivore/omnivore.
cheers

Thank you

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charsen:

ms_lim:

Can someone help to explain this question :


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Hi
Answer is (4).Under plants ,there is a sub title called reproduce by spores.Since fern is a plant and reproduce by spores since it is a non-flowering plant,z should be bird nest fern.
cheers

Thank you. Sorry to bother you. For option (4), Y is onion but why is onion reprodue by seeds? My understanding is onion is reproduced by buds. Is there any problem with this question?

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Can help to explain this question? Ans key is 1


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[charsen]

ms_lim:

charsen:

[quote=\"ms_lim\"]Can someone help to explain this question :


http://i45.tinypic.com/2uzqr7s.jpg\">

Hi
Answer is (4).Under plants ,there is a sub title called reproduce by spores.Since fern is a plant and reproduce by spores since it is a non-flowering plant,z should be bird nest fern.
cheers

Thank you. Sorry to bother you. For option (4), Y is onion but why is onion reprodue by seeds? My understanding is onion is reproduced by buds. Is there any problem with this question?[/quote]Hi
Yes.Onion does reproduce by buds.But i think they should put 'reproduce by buds instead of the'reproduction in seeds'.But this does not affect the answer.Your understanding is correct.
cheers

[charsen]

ms_lim:

charsen:

[quote=\"ms_lim\"]Can someone help to explain the answer to this question? DS ans is 4 but answer key is 2


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hi
Once you see force Z,you can find the answer.Force Z cannot act at a distance,which only could be friction as friction is produced when two surfaces rub against each other.i would say the question is badly set as they say forces and there is a option called elastic potential energy.instead,it should be elastic force.Answer cannot be 4 as gravity acts at a distance which is why we have weight.answer is 2.
Hope my explanation is clear to your DS.
encounter any problem,relate the question to the topic and concept.
cheers

Dear Charsen,

Thank you. Sorry to bother you again. My DS chose option (4) as X is gravity which acts from a distance. For option (2), X is friction but question says X can act from a distance.[/quote]Hi
Sorry for the inconvenience caused .Your DS is correct.Gravity acts at a distance and it only involves a pull force.I am not so sure of Z but anyway,that does not affect the answer.I think I might have read the question wrongly.magnetism does involve a push and a pull action.
cheers,

[charsen]

ms_lim:

Can help to explain this question? Ans key is 1


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Hi
Your DS answer which is 3,is correct.Option 4 is not the answer as the snails may have eaten up the plant.You can say option 4 when they show the observation in each day that the snails is eating the plant.I would say not possible to tell.
Option 1;Double confirm it is wrong.Only plants,not animals,need light to survive.
Option 2 is wrong as we do not know whether snails eat plants.That also comes under not possible to tell.
Thus,answer 3 is correct.
Cheers

[ms_lim]

charsen:

ms_lim:

Can help to explain this question? Ans key is 1


http://i50.tinypic.com/nt2k4.jpg\">

Hi
Your DS answer which is 3,is correct.Option 4 is not the answer as the snails may have eaten up the plant.You can say option 4 when they show the observation in each day that the snails is eating the plant.I would say not possible to tell.
Option 1;Double confirm it is wrong.Only plants,not animals,need light to survive.
Option 2 is wrong as we do not know whether snails eat plants.That also comes under not possible to tell.

Thus,answer 3 is correct.
Cheers

Charsen, thanks so much for your explanation.

[ms_lim]

charsen:

Hi

Yes.Onion does reproduce by buds.But i think they should put 'reproduce by buds instead of the'reproduction in seeds'.But this does not affect the answer.Your understanding is correct.
cheers

Thanks

[Sunflower 2000]

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Can someone help to explain the Q17? Answer key is 2.
Thanks.

[Sunflower 2000]

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Can someone help to explain Q26? Answer key is 3. Thanks.
Above 2 questions are from Pei Chun SC Prelim 2012.