Q&A - PSLE Science

[tianzhu]

Hi P5G


It’s a usual practice to wet a towel using water in a scenario as described in the question.For Q26, I am inclined to go for option (4).

Option (1) ----- The wet towel provides coldness to the body. If you interpret provides coldness as supplies coldness to the body, as heat travels from a hotter region to a lower region, the wet towel cannot supply coldness to a warmer body.
Option (2) is offside for obvious reason.
Option (3) is out as water is a poor conductor of heat.
Option (4) is logical as evaporation is a cooling process.

For Q29, I’d go for option (2).Remember that light travel in a straight line.
Note -----I think angles of incidence and reflection are not covered in primary science.I am not sure whether teachers would be very particular about this or not.As the diagram may not reflect the original one due to duplication, option(4) is also a possible answer.

For Q33, a diagram is provided and you are required to answer based on the context in the question.

This question concerns germination of seeds. In primary science, students learnt about the three conditions for germination, water, air and warmth.
There is no information given in the question to suggest that are jars are placed under sunlight.

The conditions for a plant to grow well are air, water, sunlight/light and nutrients(minerals)

Based on this question, I’d go for water and air.

Best wishes

[atutor2001]

P5G:

Please help.



http://www.orlesson.org/orp/09Sc/2009-Sc-SA1-MGS.pdf


Q26) When a child suffers from high fever, there is a practice to place a wet towel around the child's head and neck. What do you think is the possible reason for doing that?

(1) The wet towel provides coldness to the body.
(2) The wet towel is a poor conductor of heat to prevent heat from entering the body.
(3) The wet towel is a good conductor of heat to conduct heat away from the body.
(4) The wet towel allows evaporation to happen around the body.

Worksheet answer is 4).

My answer is (1.

Which is correct?

Hi P5G

In science, the terms \"hotness\" and \"coldness\" means \"temperature\".

For example, the \"coldness\" of the water is just right for bathing, means that the temperature of the water is ok.

Therefore, we cannot \"provide coldness\" (i.e. provide temperature) to a body\". The correct way to say it is \"We remove heat (energy) from the body to make it colder (i.e. of lower temperature). So the wrong science term is used in Ans 1 and is not acceptable.

[Sun_2010]

P5G:

Please help.



http://www.orlesson.org/orp/09Sc/2009-Sc-SA1-MGS.pdf


Q26) When a child suffers from high fever, there is a practice to place a wet towel around the child's head and neck. What do you think is the possible reason for doing that?
Q33c) Please refer to the question and picture attached.

My answer is sunlight and water.

Will it be acceptable?

TIA.

Hi P5G,
For 26, the option 1 - is incorrect, you can only remove heat energy from an object , cant add coldness to it.
Moreover, a wet towel will be at room temperature , so the amount of heat a transfered from the warm body to the towel is not substantial if it were not for the evapoaration of the water which needs more heat.
So ans is definetely 4.

As for the germination question 33c, seeds do NOT need exposure to sunlight for germination. Air , water and warmth ( i think temp abt 25 deg C + is ideal)

[Tang]

P5G:

Please help.



http://www.orlesson.org/orp/09Sc/2009-Sc-SA1-MGS.pdf

Q33c) Please refer to the question and picture attached.

My answer is sunlight and water.

Will it be acceptable?

TIA.

Your answer is acceptable since it refers to the young seedlings after 1 week.

The young seedlings need sunlight, air (carbon dioxide) and water to make food (photosynthesis) and oxygen for respiration.

[P5G]

Please help.



http://www.orlesson.org/orp/09Sc/2009-Sc-SA1-Nanyang.pdf


Q13.
Please advise why 'B. Both of them have tails.' is not correct.


Q25.
Worksheet answer is (2) Angsana.

My answer is (3) Mimosa.

Which is correct?


TIA.

[tianzhu]

Hi P5G


In primary science, students learn that fishes have gills to help them breathe. Most fishes have scales on their bodies.
Seahorses are fishes. Seahorses have bony plates that help protect their bodies. You may read more about seahorses by following this link.
http://www.indyzoo.com/pdf/Seahorses.pdf

Going by the context in Q13
A ----- Both seahorse and fish have gills.
B ------ Based on picture, both animals have tails. But, there are animals with tails that are not fishes, eg cow, monkey.
C ------ Fishes have scales, but here,some may say that seahorses have bony plates, not scales to protect their bodies.
D ------- Yes, both animals live in the sea. But not all animals living in the sea are fishes eg dolphin

Based on the given options, I’d go for closest option which is (1)

As for Q25, you need to have a good grasp on the modes of dispersal of fruits and seeds. Again, refer to your PSLE Science Guide, fruits and seeds dispersed by wind are dry, light, small and wing like or parachutes structures. Mimosa is classified as dispersal by animals because they have hooks or stiff hairs.

Here the key words in this question is wind dispersed fruits which rules out mimosa(classified as dispersed by animal in PSLE science Guide).Without wind dispersed fruits in this instance, mimosa would be an obvious choice.

In Q25, lalang, angsana and dandelion are wind dispersed fruits. Lalang and dandelion have fruits with fine hairs helping them float, therefore staying for a longer period in the air. I’d more inclined to go for option (2)

Best wishes

[cluelessmom]

Hi all, can anyone tell me wat is the state of matter of Jam? :?

[Muffins]

Hi cluelessmom, strawberry jam is a liquid.


A liquid is a fluid that has the particles loose and can freely form a distinct surface at the boundaries of its bulk material. The surface is a free surface where the liquid is not constrained by a container. And jam can flow freely throughout the bottle without any jams (in this sense, it means blockage) whatsoever, so it is more inclined to being classified as a liquid. That's what I think.....

[cluelessmom]

Thank U Muffins

[Muffins]

No problem!