2011 PSLE Discussions and Strategy

[stickyz]

For the lack of ___________ question, i put water.


This is my explanation:
Plants give out oxygen when they make food. When there is more oxygen, they will be able to respire faster, to produce more carbon dioxide? So its like there will always be a balance of carbon dioxide and oxygen in the container? (Not sure too).

[Randomnity]

I put carbon dioxide and circle.


In the photosynthesis question, there was a cork in the beaker to prevent water from evaporating into the surroundings and the rate of photosynthesis is higher than the rate of respiration so the rate of photosynthesis will decrease after the carbon dioxide is used up and the plant needs to respire more to release more carbon dioxide.

Then the shadow question… the metal ball is further away from the screen than the square thingy, so even though when the lines are drawn in the diagram they look about the same size, but actually the circle shadow will be bigger than the square shadow.

JMHO for putting those answers down.

[Pen88n]

OrangeJuice:

You mean the MCQ one ? Its the same . Gravity dont change .

Even when height is different?[/quote]

I thought it is gravitational energy that will change when the height is different? I thought gravitational force depend on mass? :scratchhead:[/quote]

That was how my DD explained to me too when I thot height affects the gavity lvl....[/quote]

Gravitational potential energy will change due to height, but it is not gravitational energy or force. Gravitational potential energy is the one that will change to kinetic energy when things start falling from a height or sliding down from a height. Note the difference.

[moirwong]

Q43, sand-pond question, anyone remember wat answer you wrote?

btw, why does the bird's back face the sun :rahrah:

[Guitar]

moirwong:

q43 sand-pond question. Is the water polluted? Why?

my dd write that the water is polluted because harmful chemicals that are colourless could be mixed with the water.

[papaya99]

moirwong:

q43 sand-pond question. Is the water polluted? Why?

My ans is : yes. Because other soluble impurities may be present in the water even though you cannot see them.

[stickyz]

Guitar:

moirwong:

q43 sand-pond question. Is the water polluted? Why?

my dd write that the water is polluted because harmful chemicals that are colourless could be mixed with the water.

I wrote: Water is polluted as harmful bacteria that cannot be seen through the naked eye might be in the water. (not sure if i am correct though).

[moirwong]

Yours sound correct. my dd says she wrote polluted but wrote some rubbish for the reasoning

[Junglezoo]

Guitar:

moirwong:

q43 sand-pond question. Is the water polluted? Why?

my dd write that the water is polluted because harmful chemicals that are colourless could be mixed with the water.

Hi, I said that it was to ensure only clear water comes out. (Need not to mention if water is polluted.)

[papaya99]

moirwong:

Q43, sand-pond question, anyone remember wat answer you wrote?

btw, why does the bird's back face the sun :rahrah:

My ans is : bird P's back is dark and it faces it's back to the sun so as to absorb more heat to survive in the cold environment.