Q&A - PSLE Science

[kuts]

mumthebest:

The leaves of a potted plant were completely covered with grease. The plant dies after sometimes as the leaves are not able to take in ________.

a) carbon dioxide
b) oxygen
c) sunlight
d) water

1) a and b only
2) c and d only
3) a, b and c only
4) b, c and d only

My DD says option 3

[verykiasumummy]

mumthebest:

The leaves of a potted plant were completely covered with grease. The plant dies after sometimes as the leaves are not able to take in ________.

a) carbon dioxide
b) oxygen
c) sunlight
d) water

1) a and b only
2) c and d only
3) a, b and c only
4) b, c and d only

hello, the answer is 1 (a and b)

stomata on the leaves take in air (oxygen and carbon dioxide), for gases exchange to take place. so when leaves are coated, the stomata are blocked, hence unable to take in air.

sunlight on the other hand is trapped by the chlorophyll in the leaves, since light can pass through oil, the leaves can still trap sunlight even when it is coated.

water is taken in through the roots, so there is no issue with water even when stomata is blocked.

hope it helps.

**like my post if i've helped u a bit or answered your questions correctly. many thanks...** :please: :please: :please:

[verykiasumummy]

Robertpattinsonidle:

http://i46.tinypic.com/2wqhj80.jpg\">


[b] tom inflated the balloon until it burst. state energy changes that occurred


elastic potential ?????????????? sound+kinetic energy
___________ >____________>__________?

i'm still pondering over your question leh... my ds1 still swimming at this hour, couldnt ask and discuss with him...

are there only 3 blanks??

what i can think of now is :

chemical potential energy of Tom --> kinetic energy of air --> elastic potential energy of balloon --> sound + heat energy

[superksmum]

Robertpattinsonidle:

http://i46.tinypic.com/2wqhj80.jpg\">


[b] tom inflated the balloon until it burst. state energy changes that occurred


elastic potential ?????????????? sound+kinetic energy
___________ >____________>__________?

The answer is:
Elastic potential energy (of the balloon)> kinetic energy( of the air in the balloon)> sound energy(popping of balloon).
(confirmed by DD's school science teacher).

[verykiasumummy]

Robertpattinsonidle:

verykiasumummy:

[quote=\"NY1969\"]Can someone ans this question in a scientific way:-


A metal rod is partially is submerged into an ice water. After sometimes, why is the other end of the rod becomes cool also?

Metal is a good conductor of heat, so the part that is submerged will lose its heat to the ice water quickly. And since heat travels from a hotter place to a colder place, the other end of the metal will also lose heat to the ice, causing it to be cold eventually.

note: there is no such thing as colder place. it is called cooler place.
thanks,
robertpattinsonidle ft.JB[/quote]thks for correcting, i always use cooler with my ds1. just slipped my mind while answering that...

[NY1969]

superksmum:

Robertpattinsonidle:

http://i46.tinypic.com/2wqhj80.jpg\">


[b] tom inflated the balloon until it burst. state energy changes that occurred


elastic potential ?????????????? sound+kinetic energy
___________ >____________>__________?

The answer is:
Elastic potential energy (of the balloon)> kinetic energy( of the air in the balloon)> sound energy(popping of balloon).
(confirmed by DD's school science teacher).

But the scene did not described the balloon will stretch till burst.

[superksmum]

NY1969:

superksmum:

[quote=\"Robertpattinsonidle\"]http://i46.tinypic.com/2wqhj80.jpg\">


[b] tom inflated the balloon until it burst. state energy changes that occurred


elastic potential ?????????????? sound+kinetic energy
___________ >____________>__________?

The answer is:
Elastic potential energy (of the balloon)> kinetic energy( of the air in the balloon)> sound energy(popping of balloon).
(confirmed by DD's school science teacher).

But the scene did not described the balloon will stretch till burst.[/quote]

The question was \"Tom inflated the balloon until it burst. state energy changes that occurred\". Key words are 'stretch until burst'. Although the picture didn't state, but the question did.

[Bookwrappers]

Can anyone advise me what is the difference between heart rate and breathing rate?

[Bookwrappers]

I like the ans provided by vksm for the leaves coated with oil. But i cant click the like button. Dont know why.

[Robertpattinsonidle]

superksmum:

Robertpattinsonidle:

http://i46.tinypic.com/2wqhj80.jpg\">


[b] tom inflated the balloon until it burst. state energy changes that occurred


elastic potential ?????????????? sound+kinetic energy
___________ >____________>__________?

The answer is:
Elastic potential energy (of the balloon)> kinetic energy( of the air in the balloon)> sound energy(popping of balloon).
(confirmed by DD's school science teacher).

That was my answer exactly. But ans key says no kinetic energy but it is heat energy for the second blank!!
Thanks
robertpattinsonidle ft.JB