Q&A - P3 Science

[tianzhu]

Hi


In primary science, students learnt that bread mould grows quicker in dark, wet and warm conditions.

In answering part (a), one needs to know the concept of a fair test. We conduct a fair test by making sure that we change one factor (variable) at a time while keeping all other variables the same. In this experiment, we want to find out how water affects the growth of mould in bread.

By keeping the jars airtight, one ensures that the moisture from the surrounding air does not reach the bread. Furthermore water from the bread in jar X is also not lost to the surrounding air.
Craft your answer around these pointers.

For part (b), the moisture in the bread is removed by heating in an oven and the high temperature of the oven will destroy most moulds. Therefore the bread will not be mouldy.

Do we stop here? For me, it’s a definite yes. I’ll take a walk in the park to enjoy the scenery.

However, some parents may go on and ask whether the bread is put in the jar in hot or cold conditions. The question does not give any indication. Through experiences, they may know that cookies made by lovely mothers and wives should not be kept directly from the oven into containers. As in any open ended question, there is always a tendency for multiple interpretations. I would wonder whether students would think of that under intense examination environment.

Well, it’s up to you to decide. If you want to make your life more interesting, one may argue that condensation occurs when the hot bread is placed in a jar directly from the oven, the bread may also turn mouldy. But given the fact that the condensed droplets are of very small amount and the moulds had been killed under heat from the oven, this may not be likely. You may want to carry out an experiment to satisfy your curiosity.

Well, talking about lovely mothers and wives, I wish to take this opportunity to wish all mothers
Happy Mother’s Day

Best wishes

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[kitty2]

:thankyou: for all the replies,all of you are great!!!!!

[Puffer]

A question on Life Cycle:


There are 3 and 4 stages in a life cycle. True or False?

[tutormum]

False. There are 2 stages, 3 stages and 4 stages life cycles.

[Puffer]

First, my apologies to KS Chief and monitors for posting this wrongly - should have posted under P3/4 Science.


My DS’ Science teacher seems to have mentioned that presently, the PSLE people have ‘agreed’ that there will be no 2-stage cycles for man and most mammals. They have argued that the egg contained in the human body is considered one stage. I need experts’ advice please.

[ruyu]

True. Mammals have a three stage life cycle consiting of egg,young and adult.

[elkniwt]

Please help with this MCQ - Qn 6,


http://www.orlesson.org/orp/09Sc/P3-09-Sc-SA2-RGS.pdf

Shouldn't the answer be (1) Setup A ?? :?

[Muffins]

Hi elkniwt, in my opinion, Set-up A should be the right answer. In Set-up B, the bread is not toasted, so there is still moisture in it that can give rise to mould growing on it, but for Set-up A, it should not be that mouldy, as compared to B. :? :?


Expert Tianzhu, what's your take on this?

[tianzhu]

Hi elkniwt and muffins,

Good Morning,

Looking at this question, it is hard not to miss one word in upper case and bold. Why do you think LEAST might mean from the context of this question? What clues does the setter intend to give?

In this instance, I shall take LEAST to mean the lowest, fewest or smallest in number.

In primary science, students learnt that bread mould grows quicker in dark, wet and warm conditions.

The toaster heats up the bread and removes the moisture from them; therefore it’s not likely to have moulds after three days. Hence option (1) and (3) are offside.
Between option (2) and (4), I’d go for option (2) because the amount of air in the sealed bag is limited.

Before I go off, muffins, I am no expert. I am a victim of circumstances. I am also learning as I answer questions because I’ve to do further reading.

Best wishes

[Puffer]

ruyu:

True. Mammals have a three stage life cycle consiting of egg,young and adult.

Thanks ruyu for confirming my doubt. So I can safely say that there will be NO 2-stage life cycle? How about bacteria (I know this is unlikely to be tested in P3-4 context)? I shall confirm this with the Science teachers.