Q&A - PSLE Science

[Verysuperkiasu]

tianzhu:

I guess a logical explanation is that a bigger animal(assuming non plant eater) has a bigger body and with that a bigger appetite, hence their chances of survival decreases when food becomes scarce.

As to your second question on the limit for recycled air, please refer to the last paragraph(brief history) of the article.

Hope this helps.

Best wishes

Thanks, Tianzhu for your detailed explanation. And very informative article too....

[IMTRYINGSTUFF]

Ash001:

Need help here. School answer is 4

My son answer is 1

I had asked my son to asked the teacher.
-Her explanation is diagram C is with same brightness. I am not convinced here. Look at the qns once again, the keyword is \"light up\" with \"equal brightness\"

-I dont really know the explanation on diagram D as my son didnt understand what she was saying. This diagram D confirm only the upper bulk get light up.


http://i56.tinypic.com/1109550.jpg\">

I can't see the image. It's too small

[IMTRYINGSTUFF]

Nebbermind:

Verysuperkiasu:

Picture shows an glass aquarium with aquatic plants and some animals like fish, waterboatman and water fleas. Tank is sealed with a glass plate and whole aquarium placed in a brightly lit room the whole day.


Qn : Which of the following statements is correct about the organisms after several months?

1) All the organisms will die as there is hardly any air in the tank
2) The plants can survive longer than the larger animals in the tank
3) The animals will all die in less than a day as there is insufficient air
4) The organisms could still survive as there is a continuous supply of air.
Answer is 2)

Son's answer is 4) as there is a constant exchange of gases between the plants and animals - plants give out oxygen (during photosynthesis as the glass aquarium is placed in the light whole day) for the animals to take in and animals breathe out CO2 for the plants to take in. But my question is 'can this exchange of gases take place forever in a sealed container - is there a time limit to this? Note the question says 'after several months'.

My answer is 2). The plants will survive the longest as the conditions of the surroundings have fulfilled the necessary conditions for survival. They have oxygen from the oxygen they made from photosynthesis, food from photosynthesis and water all around them. However, the animals do not have food.

[tianzhu]

Ash001:

Need help here. School answer is 4

My son answer is 1

Hi

Please watch this video.

It helps to address your query on diagram C.

http://www.youtube.com/watch?v=jxMV0wagR8o&feature=related

Best wishes

[tianzhu]

Verysuperkiasu:

Thanks, Tianzhu for your detailed explanation. And very informative article too....

Hi

You're welcome.

Best wishes

[chrisu]

Your son's answer is right, the answer is (1) - A and B both in fact are the same, just that the battery is shifted to the left.


Diagram C, bulb will not light up and Diagram D only the top bulb will light up (as you have mentioned). Both C and D are due to the shorted path.

In fact the very top given diagram, the bulb will not light up as it's a shorted path across the battery.

Also I wonder why the need to show the very top diagram as the question is not ask to compare the same brightness as the top diagram. The question only ask same brightness for the 2 bulbs.

Seems like a number of schools are making the same mistake over and over again. Maybe MOE should stop school from setting questions that the teachers themselves are not familiar with.

Ash001:

Need help here. School answer is 4
My son answer is 1

I had asked my son to asked the teacher.
-Her explanation is diagram C is with same brightness. I am not convinced here. Look at the qns once again, the keyword is \"light up\" with \"equal brightness\"

-I dont really know the explanation on diagram D as my son didnt understand what she was saying. This diagram D confirm only the upper bulk get light up.



http://i56.tinypic.com/bdwjv8.jpg\">

[Ash001]

Thank you Tianzu & Chrisu.


In fact, before I wrote to the teacher, my husband and son had conducted the experiment to prove diagram C&D is out.
Yesterday, the teacher explained to my son and still insist school ans is correct. Which troubled us alot!!!
She claimed that Diagram C has same brightness

When I read the question once again. I caught the keyword "light up" with "equal brightness". My interpretation here is the diagram has to fulfil 2 condition, light up and with equal brightness.
Am I wrong???

[tianzhu]

Ash001:

Thank you Tianzu & Chrisu.


In fact, before I wrote to the teacher, my husband and son had conducted the experiment to prove diagram C&D is out.
Yesterday, the teacher explained to my son and still insist school ans is correct. Which troubled us alot!!!!!
She claimed that Diagram C has same brightness

When I read the question once again. I caught the keyword \"light up\" with \"equal brightness\". My interpretation here is the diagram has to fulfil 2 condition, light up and with equal brightness.
Am I wrong???

Hi

You're welcome.

Diagram C is pretty similar to the configuration shown in the video.
The two bulbs will not be lighted up as currents bypass them through the wire which offers little resistance.

Both lights are not lighted up.

There was also a discussion on a similar type of question on page 120 of this thread.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=1727&start=1190

You may wish to write to your kid’s teacher again to ask him/her why the two bulbs of equal brightness.

Best wishes

[chrisu]

You are welcome Ash001.


I'm worried that the marker for PSLE mark wrongly for such questions in the PSLE Science. Parents cannot even check as papers are not returned. There may be a chance since so many teachers in so many schools also got it wrong.

Ash001:

Thank you Tianzu & Chrisu.

In fact, before I wrote to the teacher, my husband and son had conducted the experiment to prove diagram C&D is out.
Yesterday, the teacher explained to my son and still insist school ans is correct. Which troubled us alot!!!!!
She claimed that Diagram C has same brightness

When I read the question once again. I caught the keyword \"light up\" with \"equal brightness\". My interpretation here is the diagram has to fulfil 2 condition, light up and with equal brightness.
Am I wrong???

[Ash001]

Hi Tianzhu/Chrisu,


I did see that qns on pg120 before I post mine I showed that to my husband, he said none of the answer is correct.
Yes indeed it is worrying to see MOE teachers setting question with no correct answer and still insist the school answer is correct. OMG!!!!

About the \"brightness\", it is very subjective to how one define the meaning of brightness. To me, it has to be lightup before it can be measured for brightness. But for others, even if it is not lightup, their consider the 2 bulk is of equal brightness.

Cheers