Q&A - PSLE Science

[atutor2001]

Hi tianzhu


Your illustration is so wonderful. It shows your interpretation very clearly and I think your interpretation will definitely be correct if the temp. difference between the surrounding air and the milk is big.

Thank you

Regards

[tianzhu]

glchua:

Not true. Water needs a lot of heat to increase 1 degree of temperature. Compared with iron, it is about 10 times more! Energy required to pull the orderly molecules from a solid state to a messy and energetic liquid state is very high too.

Hi

Thank you for your view. I am trying to look at this question from the concepts on heat learned in P4.

What would our primary kids think when they first read this question? Formula such as Q =mass x specific heat x temperature difference, specific heat capacities of water and iron and latent heat of fusion are not taught yet.

In Q26, one has to compare the heat gained by the water from the hot iron as compared to the heat gained by the melting cube of ice, bearing in mind that the beaker of water has greater mass than the cube of ice.
Primary students learn that heat flows from a higher region to a lower region. Hence, in applying this principle, a bigger temperature difference, greater heat gain for the water in the beaker(option 2).

This is how I would have answered this question. Of course my answer may not be right.

Best wishes

[tianzhu]

Hi


There are many questions from past year papers on measuring photosynthesis rates by counting the number of bubbles. This essay on floating leaf disk explores another way of measuring photosynthesis.

Happy reading

Best wishes.
http://www.elbiology.com/labtools/Leafdisk.html

[atutor2001]

Hi tianzhu


A very interesting article indeed. Thank you.

However, an immediate question came to my mind - Why can a plucked leaf continue to carry out photosysnthsis?

My guess is that the cells of in a plucked leaf are "alive" for quite a number of days. That brings my thought to the term "alive". Is it right to say that the cells are "alive" or should it be "functional" or some other biological term. Thanks in advance.

Regards

[tianzhu]

atutor2001:

However, an immediate question came to my mind - Why can a plucked leaf continue to carry out photosysnthsis?

Hi atutor2001

Glad you find it interesting. I came across this article while doing some readings for this question.

http://www.mathsheuristics.com/mathsHeuristics_flyer.pdf --- Please refer to question at pg 2.

I don’t have any answer to your question now, but will do some further reading.

Meanwhile let’s hear what others have to say.

Best wishes

[atutor2001]

Hi tianzhu


Actually the "apple question" is still bothering me. If some of the cells in a plucked leaf is alive, then some of the cells in a "pluck apple" will probably also be alive. That leads to my frustration of whether is the leaf or apple, as a whole, considered to be alive i.e. living thing.

Have tried googling but so far couldn’t find any satisfactory answer. Hope you can hit one. Thanks.

Regards

[tianzhu]

atutor2001:

Actually the \"apple question\" is still bothering me.

Hi atutor2001

Hope this article helps.
http://www.scholastic.ca/education/science_place/downloads/alive_tg_on.pdf

Have fun.

Best wishes

[atutor2001]

Hi tianzhu


Thanks

[Full.010894Cream]

an interesting article on leave disk indeed!!


BTW, what's the conclusion on the 'apple'? :?

[atutor2001]

Hi Full.Cream


Most of the articles indicated that picked apple is dead. Those that said that it is still alive concluded so because they had included the seeds as part of the apple. However, the definition of fruit (apple is a fruit) does not include the seeds as part of a fruit. (A fruit is the fleshy part that protects the seeds and helps in seed dispersal.)

When I tried to match the 7 characteristics of a living thing to a picked apple, most of the characteristics do not match. So I have accepted and concluded that a picked apple is DEAD