Q&A - PSLE Science

[atutor2001]

Verysuperkiasu:

This was also my question.....the below article might help?

http://factoidz.com/boil-water-in-a-paper-cup/

Just scroll down a little

Thank you very much for the information.

[Cockroach]

vidhyalog:

For the below OE - for part 1 - my son's answer reads \"the higher the temperature the more air bubbles will appear in the beaker and vice versa\". However I feel this is an observation - not hypothesis. The answer key says the hypothesis is that \"the higher the temperature the higher the rate of photosynthesis.' But my son insists they were told to use the variables provided to them to give the answers.


Would appreciate views on this. http://i53.tinypic.com/auyvd.jpg\">

I would write this for the hypothesis instead as your son's answer is not that accurate. (The number of air bubbles would increase as the heat intensity increases.) Your son's way of answering is only accepted if the questions is \" what can you conclude from the ......\" :what can you tell about the......\" etc

[Cockroach]

Please help



http://i52.tinypic.com/307w1eg.jpg\">

TIA( my son's answer is 4 but the model answer was 2)

[cimman]

Cockroach:

vidhyalog:

For the below OE - for part 1 - my son's answer reads \"the higher the temperature the more air bubbles will appear in the beaker and vice versa\". However I feel this is an observation - not hypothesis. The answer key says the hypothesis is that \"the higher the temperature the higher the rate of photosynthesis.' But my son insists they were told to use the variables provided to them to give the answers.


Would appreciate views on this. http://i53.tinypic.com/auyvd.jpg\">

I would write this for the hypothesis instead as your son's answer is not that accurate. (The number of air bubbles would increase as the heat intensity increases.) Your son's way of answering is only accepted if the questions is \" what can you conclude from the ......\" :what can you tell about the......\" etc

I would go with the answer key answer. The answer should link back to a topic within the PSLE syllabus, which in this case is photosynthesis. The hypothesis of the bubbles does not seem to achieve much in the way of an experimental objective, ie. there is no higher order objective. Yes, it explains the relationship between heat and the bubbles, but it begs the question, What causes the bubbles ? which is a higher order objective.

By putting in photosynthesis, and saying the the process producess gases both in the absence and presence of sunlight, the bubbles are explained and an additonal factor, ie heat, is brought to photosynthesis equation, in addition to sunlight.

[Tang]

cimman:

Cockroach:

[quote=\"vidhyalog\"]For the below OE - for part 1 - my son's answer reads \"the higher the temperature the more air bubbles will appear in the beaker and vice versa\". However I feel this is an observation - not hypothesis. The answer key says the hypothesis is that \"the higher the temperature the higher the rate of photosynthesis.' But my son insists they were told to use the variables provided to them to give the answers.


Would appreciate views on this. http://i53.tinypic.com/auyvd.jpg\">

I would write this for the hypothesis instead as your son's answer is not that accurate. (The number of air bubbles would increase as the heat intensity increases.) Your son's way of answering is only accepted if the questions is \" what can you conclude from the ......\" :what can you tell about the......\" etc

I would go with the answer key answer. The answer should link back to a topic within the PSLE syllabus, which in this case is photosynthesis. The hypothesis of the bubbles does not seem to achieve much in the way of an experimental objective, ie. there is no higher order objective.
By putting in photosynthesis, and saying the the process producess gases both in the absence and presence of sunlight, the bubbles are explained and an additonal factor, ie heat, is brought to photosynthesis equation, in addition to sunlight.[/quote]
Hi,

In my personal opinion, the answer provided by the pupil is perfect for this question.

The bubbles produced do not come from photosynthesis but respiration in this case.

Hypothesis may not be true and can be proven by the experiments.

[Tang]

atutor2001:

P5G:

Please help.


http://i56.tinypic.com/16jj4mg.gif\">


TIA.

I will pick (2) because its twisted look appears to be more suitable for clinging to tree trunks.

Hi,

I have done an online search for pictures of woodpecker, the photophoto shows that the correct answer should be (4).

[Tinkerbelle]

Verysuperkiasu:

ms_lim:

Please help to explain Qn #25 from Pei Chun 2011 Prelim, Ans key is 2 :


http://i55.tinypic.com/ehu0x.jpg\">

This was also my question.....the below article might help?

http://factoidz.com/boil-water-in-a-paper-cup/

Just scroll down a little

Interesting. Thanks for sharing, verysuperkiasu.

[Tang]

atutor2001:

P5G:

Please help.


http://i54.tinypic.com/r8573s.gif\">


TIA.

To me both (1) and (3) are possible options but I will pick (1) because of the words \"after a day\".

For some seeds, it will take a long time to germinate unless we soak the seek in water first (e.g. rice grain). So I am assuming that the time needed for a seed to germinate is primarily determined by the time needed for the seed to absorb sufficient water. Therefore, in the above experiment, during the period where there is no air, it allows time for the seed to get thoroughly soaked. Once air is introduced, the seed can carry out cell respiration immediately to release energy for germination to begin.

Hi,

Since the seeds germinate after a day, the changed variable must be something that is not necessary for germination to take place. So answer should be (2) or (4). But since this is a Science question, I will just have to pick (2) as my final answer.

[Verysuperkiasu]

Tinkerbelle:

Interesting. Thanks for sharing, verysuperkiasu.

You're welcome

[Verysuperkiasu]

peichun prelim 2011 section b q39b


Mr Leong wanted to use a metal barbecue grill P or Q, that would result in the food being less burnt.

Picture of P shows some thinner metal strips with bigger gaps between the strips.
Picture of Q shows some thicker metal strips with narrower gaps between them.

Based on the diagram, which grill should he use. Give a reason.

Answer key is Q. thicker strips = large surface area in contact = conduct heat away faster to the air so food won't get burnt. My question ; but won't the bigger surface area of the strips also conduct heat faster to the food as well which will burn the food?

If choose P, also not right coz the bigger gaps means fire in direct contact with the food which will get burnt.

Pls enlighten me....