Q&A - PSLE Science

[NY1969]

charsen:

superksmum:

Hi all,

Need some advice on what greenhouse effect is and how it benefits plants. Does it also have negative and positive effects?

TIA

Hi
Green house effects is the amount of green house gases like carbon dioxide in the atmosphere.These green house gases trap heat from the sun .As there are more green house gases in the atmosphere,more heat from the sun is trapped in the earth 's atmosphere.There is no positive effect on the plants due to the green house effect as far as i know.But,the negative effect is global warming an the rise of sea levels.
Charsen

Is greenhouse effect tested in exam?

[cccleo]

NY1969:

cccleo:

What's the difference between steam and air?

Steam-- contains high content of water vapour in a specific volume of air

Air-- general term only

So bubble in boiling water at 100degrees can be considered as steam, hot water vapour and air? :scratchhead:

[cccleo]

NY1969:

charsen:

[quote=\"superksmum\"]Hi all,

Need some advice on what greenhouse effect is and how it benefits plants. Does it also have negative and positive effects?

TIA

Hi
Green house effects is the amount of green house gases like carbon dioxide in the atmosphere.These green house gases trap heat from the sun .As there are more green house gases in the atmosphere,more heat from the sun is trapped in the earth 's atmosphere.There is no positive effect on the plants due to the green house effect as far as i know.But,the negative effect is global warming an the rise of sea levels.
Charsen

Is greenhouse effect tested in exam?[/quote]Yes.

[superksmum]

charsen:

superksmum:

Hi all,

Need some advice on what greenhouse effect is and how it benefits plants. Does it also have negative and positive effects?

TIA

Hi
Green house effects is the amount of green house gases like carbon dioxide in the atmosphere.These green house gases trap heat from the sun .As there are more green house gases in the atmosphere,more heat from the sun is trapped in the earth 's atmosphere.There is no positive effect on the plants due to the green house effect as far as i know.But,the negative effect is global warming an the rise of sea levels.
Charsen

Hi Charsen,
Thanks, u have been very helpful. Is global warming a negative effect also?

[charsen]

NY1969:

charsen:

[quote=\"superksmum\"]Hi all,

Need some advice on what greenhouse effect is and how it benefits plants. Does it also have negative and positive effects?

TIA

Hi
Green house effecths is the amount of green house gases like carbon dioxide in the atmosphere.These green house gases trap heat from the sun .As there are more green house gases in the atmosphere,more heat from the sun is trapped in the earth 's atmosphere.There is no positive effect on the plants due to the green house effect as far as i know.But,the negative effect is global warming an the rise of sea levels.
Charsen

Is greenhouse effect tested in exam?[/quote]Hi
Grenn house effect is tested under the topic man and his environment.
Charsen

[smurfalone]

verykiasumummy:

smurfalone:

Need help :-

NY 2010 SA2 #15

http://i47.tinypic.com/23laxia.jpg\">
Answer key is 1 - is it correct ?

hi smurfalone,

yes ans is 1. (A and B)

A) flower will attract pollinators to it = promotes animal pollination.
B) flower has nectar = attracts animals to eat.
C) anther shorter than stigma = shows pollen grains will be brushed on animals when they are feeding on their nectar. (but pollen grains brushed on these animals will help to pollinate other flowers when the animals go to other flowers, not the same flower) D) stigma sticking out = shows stigma easily pollinated by wind.

so only A and B, ans = 1.

:thankyou: verykiasumummy
I agree with A, B and D but don't understand C (the part in red italics) as the question didn't mention pollinate the same flower.

[charsen]

Hi smurfalone,

If you see the flower carefully,the anther and the stigma is on the flower.When the animals suck the nectar,the pollen grains would be brushed on the animal.Then,the animal would brush the pollen grains on it in the stigma to get rid of it.This is the explanation for option C.Wind pollination occures when both the anthers and the stigma stick out of the flower.The stigma is longer than the anther so as to give soace for the animal to brush the pollen grains on it.
Charsen

[Sunflower 2000]

http://i45.tinypic.com/25dlf.jpg\"> Can somebody help to explain why isn't A acceptable?

[smurfalone]

charsen:

Hi smurfalone,

If you see the flower carefully,the anther and the stigma is on the flower.When the animals suck the nectar,the pollen grains would be brushed on the animal.Then,the animal would brush the pollen grains on it in the stigma to get rid of it.This is the explanation for option C.Wind pollination occures when both the anthers and the stigma stick out of the flower.The stigma is longer than the anther so as to give soace for the animal to brush the pollen grains on it.
Charsen

Hi Charsen
Understand now, :thankyou: for your detailed explanation

[smurfalone]

charsen:

smurfalone:

Need help :-

NY 2010 SA2 #18

Asnwer key is (1), is it correct ? My guess is (2)
http://i48.tinypic.com/2zozw9e.jpg\">

Ans (1) Heat energy (from sun) --> Light energy

Hi Charsen
Can I trouble you to explain why the answer should be (1) ?