Q&A - PSLE Science

[glchua]

For any plucked fruit, physiological processes are still happening. A banana still ripens, mangoes give off heat if you encase it. An apple is thus still living.


If a dismembered plant is immediately considered dead, then grafting is not possible as a farming technique.

This is also true of dismembered parts of an animal. The tissue is still alive.

The apple is considered dead when it starts to rot. Respiration ceases, defense ceases, and microbes take over.

Sorry, just my opinion.

[glchua]

tianzhu:

glchua:

Not true. Water needs a lot of heat to increase 1 degree of temperature. Compared with iron, it is about 10 times more! Energy required to pull the orderly molecules from a solid state to a messy and energetic liquid state is very high too.

Hi

Thank you for your view. I am trying to look at this question from the concepts on heat learned in P4.

What would our primary kids think when they first read this question? Formula such as Q =mass x specific heat x temperature difference, specific heat capacities of water and iron and latent heat of fusion are not taught yet.

In Q26, one has to compare the heat gained by the water from the hot iron as compared to the heat gained by the melting cube of ice, bearing in mind that the beaker of water has greater mass than the cube of ice.
Primary students learn that heat flows from a higher region to a lower region. Hence, in applying this principle, a bigger temperature difference, greater heat gain for the water in the beaker(option 2).

This is how I would have answered this question. Of course my answer may not be right.

Best wishes

I apologize if I offended. My calculations may not be right too, since these stuffs are learnt long ago and I don't use these knowledge in my current line of work, not frequently anyway.

The issue here is not the answer. The original question from the school is wrong. One can't assume that all students see things in the limited light of what the teacher had taught. So it boils down to learning for giving correct answers, or learning to get closer to the truth.

Students who knew a little bit more through parents, internet, reading, etc would give a wrong answer or would get confused. If answers require careful phrasing (as some previous post had suggested), then teachers should do so too.

[Full.010894Cream]

Need some help here.


CHIJ 2008
http://img697.imageshack.us/img697/5417/chij2008q1.jpg\">
Ans : (3)

I understand spider does not have feelers

http://img4.imageshack.us/img4/8606/chij2008q22.jpg\">
Ans : (2)

How come (D) is true?

[tianzhu]

Hi

Are you preparing for PSLE 2010?

Q1) Observe the picture. Do not assume that animal X is a spider as the question did not specifically provide this information.
Animal Y has only 3 body parts, therefore it’s incorrectly represented.

Q22) Water appears in three different kinds of stages. The liquid stage of water is between 0 and 100 degrees Celsius. At 100 degrees Celsius water reaches its boiling point. At 0 degrees Celsius,ice starts to form.
Heat is applied from A to B. Water reaches its boiling point at B. At this stage, water changes into steam.
Therefore, water exists in two different states during period AB.

Best wishes

[tianzhu]

Hi glchua


No worries, I only have sweet moments in this forum.

It’s always good to look at a question from different angles. A more vibrant discussion will benefit members in the long run.

Best wishes

[tianzhu]

Hi atutor2001


I’ve tried unsuccessfully to find articles on whether a plucked leaf is a living thing or not. I take it as a non living thing just like a plucked apple.

Best wishes

[mrswongtuition]

tianzhu:

Hi atutor2001


I’ve tried unsuccessfully to find articles on whether a plucked leaf is a living thing or not. I take it as a non living thing just like a plucked apple.

Best wishes

I asked this question to my HOD of Science (she is a Biology trained teacher).

She says that the plucked leaf is a living thing until it shows signs of decay to indicate that it is dead, i.e. a non-living thing.

She says it's the same for fruits. Her explanation is very similar to glchua. (!!! Are you my boss??? !!!)

[atutor2001]

tianzhu:

Hi atutor2001


I’ve tried unsuccessfully to find articles on whether a plucked leaf is a living thing or not. I take it as a non living thing just like a plucked apple.

Best wishes

Hi tianzhu

Thank you very much.

Regards

[tianzhu]

Hi atutor2001


Nice to have you back. Does this signal the beginning of a new season?

Best wishes

[tianzhu]

mrswongtuition:

She says that the plucked leaf is a living thing until it shows signs of decay to indicate that it is dead, i.e. a non-living thing.

Hi Mrs Wong

Thank you.

Best wishes