Q&A - P3 Science

[Zann]

MdmKS:

watmekiasu:

I guess plucking the leaves would be changing the setting. But if leaves were plucked, there would be no/less transpiration and photosynthesis.

What I was thinking may be not to pluck all but pluck some leave cos the objective is to slow down the process. BTW, will plcking all the leave cause the plant to die ?

I quite agree with tianzhu's focus on the roots method.

I was wondering why a need to have a stopper in this set-up intially till I read tianzhu's suggestion.

[atutor2001]

Zann:

I was wondering why a need to have a stopper in this set-up intially till I read tianzhu's suggestion.

I think the stopper is to prevent water lost due to evaporation.

[tianzhu]

atutor2001:

I think the stopper is to prevent water lost due to evaporation.

Hi

I agree with you that the stopper does help to prevent evaporation of water from the flask, but it’s of little relevance to this experiment. The main objective is to find out ways for the plant to absorb less water without changing the experiment settings.

Besides adjusting the depth of the roots in water, I tend to agree with your suggestion of coating the leaves with vaseline/oil. Alternatively you may cover some of the leaves with black pieces of water. This may not be considered as changing the settings but as modification of variables. The plants and flask still remain the same.

MdmKS, please let us know the answers when your child receives them.

And, you may post images by following these links.
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=2699&start=15
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=3767&start=30

[Dharma]

tianzhu:

atutor2001:

I think the stopper is to prevent water lost due to evaporation.

Hi

I agree with you that the stopper does help to prevent evaporation of water from the flask, but it’s of little relevance to this experiment. The main objective is to find out ways for the plant to absorb less water without changing the experiment settings.

Besides adjusting the depth of the roots in water, I tend to agree with your suggestion of coating the leaves with vaseline/oil. Alternatively you may cover some of the leaves with black pieces of water. This may not be considered as changing the settings but as modification of variables. The plants and flask still remain the same.

MdmKS, please let us know the answers when your child receives them.

And, you may post images by following these links.
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=2699&start=15
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=3767&start=30

To slow down the rate of absorption of water by the roots, we have to try to reduce the water loss through the leaves by transpiration. As temperature affects the rate of transpiration, the plant is to left in a cool environment e.g. an air conditioned room.

The second method is to place the set-up in a location where there is reduced intensity of light energy. This will help to slow down the rate of photosynthesis and therefore will reduce the absorption rate of water by the roots.

[atutor2001]

Hi tianzhu


The meaning of \"setting\" is bugging me. From the dictionary, there are many meanings and I have listed the relevant ones :

1. the position or adjustment of something, as a dial, that has been set
2. the time, place, environment, and surrounding circumstances of an event, story, play, etc.

From the meaning of \"setting\", it appears that the question would not allow the environment or positions of any of the components in the set-up to be changed.

However, can we then add new things to the set-up such as black paper or vaseline?

Not sure what is your opinion?

Regards

[Dharma]

tianzhu:

Hi Dharma


I’ve been looking at this question for quite a number of times. It’s a pretty interesting one.

The first diagram shows the brown gas in a jar.
The second diagram shows the brown gas occupying the volume of the jar as well as the flask. It expands.
From the first diagram, the brown gas take up a smaller space in the jar .Therefore it can be compressed. After the cardboard is removed, it expands to take up the combined capacities of the jar and flask.

So this experiment shows that air has no definite shape, volume and is compressible. What’s your view on this?

I think that the fact that the cardboard is placed on top of the jar does not tell us that the brown gas is being compressed. To demonstrate compressibility of gas, we can use an airtight rubber stopper with a plunger placed on the mouth of the jar and push it down to show that the brown gas can be compressed. Other ways are by pumping in additional volume of brown gas into the jar and measuring its mass before and after. It will show that mass will increase as air has mass but volume is still the same. The additional volume of gas that was pumped in is compressed to fill the same volume of the jar.

[tianzhu]

Hi atutor2001


I am also not sure.

I think there is lots of guess work in the interpretation of this question because we don’t have a chance to see the complete question.

May I suggest we hold our curiosities for a bit longer? Wait for MdmKS to post the image or give us the answer from her child’s teacher.

In many primary science questions, locations where the experiments are conducted are considered as one of the variables to ensure a fair test.

I think we put this question on hold now till we see further reply from MdmKS.

Best wishes

[Full.010894Cream]

atutor2001:

Hi tianzhu


The meaning of \"setting\" is bugging me. From the dictionary, there are many meanings and I have listed the relevant ones :

1. the position or adjustment of something, as a dial, that has been set
2. the time, place, environment, and surrounding circumstances of an event, story, play, etc.

From the meaning of \"setting\", it appears that the question would not allow the environment or positions of any of the components in the set-up to be changed.

However, can we then add new things to the set-up such as black paper or vaseline?

Not sure what is your opinion?

Regards

it'll be really interesting to see what's the school's answer. here we have so many parents struggling with both the science and english aspects of the qn!

[tianzhu]

Hi Dharma


I am thinking along this line, basing on the observation of the diagrams in this question.

The same amount of brown gas can be stored in the jar as shown in the first diagram.
The second diagram shows that the brown gas can be expanded to take a bigger volumes (jar and flask)

As seen from the first diagram, the brown gas is occupying a smaller volume as compared to the second picture. Therefore, it’s compressed, otherwise,how can it take up a smaller space.

Best wishes

[MdmKS]

tianzhu:

atutor2001:

I think the stopper is to prevent water lost due to evaporation.

Hi

I agree with you that the stopper does help to prevent evaporation of water from the flask, but it’s of little relevance to this experiment. The main objective is to find out ways for the plant to absorb less water without changing the experiment settings.

Besides adjusting the depth of the roots in water, I tend to agree with your suggestion of coating the leaves with vaseline/oil. Alternatively you may cover some of the leaves with black pieces of water. This may not be considered as changing the settings but as modification of variables. The plants and flask still remain the same.

MdmKS, please let us know the answers when your child receives them.

And, you may post images by following these links.
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=2699&start=15
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=3767&start=30

No problem. Hope can still make it before PSLE Science, just in case.