Q&A - PSLE Science

[lizawa]

tianzhu:

Thank you for your help.

http://farm3.static.flickr.com/2167/3530920904_2a982cebce_o.jpg\">

I think all the options for this MCQ are incorrect.Is it appropriate to classify as \"reproduce from roots\" ?

African Tulip, radish and carrot -----seeds
palm ------ suckers
yam ----- underground stem.

What's your view?

Hi tianzhu,

think you are right. There is no \"reproduction by roots\". carrot reproduce from seeds but it is the root that we eat.

[tianzhu]

Going back once again to the diving’s question, it’s a trendy one being crafted during the year of Beijing Olympics 2008.


First be mesmerised by the beauty, grace and elegance of China’s Guo Jing Jing.
http://www.youtube.com/watch?v=hNUE1h3I_kw

Next take a plunge into the physics of diving
http://www.unc.edu/~lahol/ (for further readings)

Have fun.

[snowz]

tianzhu:

Thank you for your help.

http://farm3.static.flickr.com/2167/3530920904_2a982cebce_o.jpg\">

I think all the options for this MCQ are incorrect.Is it appropriate to classify as \"reproduce from roots\" ?

African Tulip, radish and carrot -----seeds
palm ------ suckers
yam ----- underground stem.

What's your view?

ginger, onion, yam - underground stems
begonia, bryophyllum - leaves
African Tulip - seeds
carrot, radish - roots (other examples are turnip, sweet potato and lotus roots)
palm - suckers
The answer is 3.

[tianzhu]

Living Together


Thank you for your help.

A population is a group of similar organisms that lives and reproduce together in the same place.
The only population I can identify is (B) --- caterpillar, butterfly, butterfly pupa
Could you help to explain your answer?

http://farm4.static.flickr.com/3565/3552205793_95266cf62b_o.jpg\">

[tianzhu]

Simple machines ---Gears


Thank you for your help.

Part (a) is straight forward.
Part (b) --- Without any doubts, Gear Y will turn more rounds as its diameter is smaller than Gear Z.But, how many more?Could we tell based on the information given in the question?

http://farm4.static.flickr.com/3333/3552205861_3037e9de49_o.jpg\">

[tianzhu]

Living Together/Food Web


Thank you for your help.

What's your take on part(b)?

http://farm4.static.flickr.com/3558/3553015310_8ae7f582f7_o.jpg\">

[tianzhu]

Heat


Thank you for your help.

For part(a) ---It's not a fair test.The areas of exposed surfaces to the surroundings as well as the area of contact between the ice and the materials affect the time taken for the ice to melt.What's your view?

For part(b) --- The temperature of the ice remains the same, while the temperature of material X decreases.Do you agree?

http://farm4.static.flickr.com/3395/3553015402_89930b555e_o.jpg\">

[tianzhu]

Energy


Thank you for your help.

Based on the information in the question, can we tell how high the rubber ball will reach after bouncing off the concrete surface?
(2) or (3) or anywhere between(2) and (3) are logical answers.Some of the KE has been converted into heat and sound energy, hence the ball will not rebound to its original position.

http://farm4.static.flickr.com/3638/3552206045_f1f6136f0b_o.jpg\">

[ChiefKiasu]

tianzhu:

...Part (b) --- Without any doubts, Gear Y will turn more rounds as its diameter is smaller than Gear Z.But, how many more?Could we tell based on the information given in the question?

...

Yes we can, by counting the number of spokes on the gears.
Gear Y = 10
Gear Z = 16
Ratio = 16:10 => if Gear Z turns 1 round, Gear Y would have turned 1.6 rounds.

So if Gear Z turns 5 rounds, Gear Y would have turned 5x1.6=8 rounds.

[tianzhu]

Thank you for your help.


http://farm4.static.flickr.com/3314/3561514633_fbc309c8be_o.jpg\">