Introduction
Welcome back to our Examination Paper Analysis series!
In this article, we will be analysing a question on the topic of Fungi and Bacteria from the 2020 Methodist Girls’ School (MGS) P4 SA2 Examination Paper.
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Let’s Take A Look At This Question
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
Thought Process
Before we take a look at the set-ups, let us recall: which group of living things does mould belong to?
Mould is a type of fungi.
🍄 Fungi Needs WOW To Grow 🍄
W is Water
O is Oxygen
W is Warmth
These are the conditions needed for the mould to grow, but in this question, we want to know which set-up the mould would first appear in. For the mould to first appear on the orange, this tells us that all three conditions must be present.
Let’s Take A Look At Set-up A
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
For each set-up, let’s consider the conditions mentioned earlier. Let’s take a look at the first one, water. Is there water in Set-up A? The answer is no.
Why is that so? If you look at set-up A, there is a substance that absorbs moisture. This tells us that all the water vapour in the air is being absorbed, which means there is no water.
What about oxygen? Is there oxygen in this set-up? The answer is yes.
How can we tell? If you look at set-up A, we can see it is covered by wire mesh, which has many tiny openings. Because of the tiny openings, we know that air or oxygen from the surroundings can enter.
Therefore, oxygen is present.
What about the last condition: warmth? Let us recall that Mel placed the four oranges at room temperature. When it’s at room temperature, is there warmth? Definitely!
Are all three factors present in this set-up? No! Do you think the mould can appear on the orange? The answer is no.
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
Let us then cross out set-up A.
Let’s Take A Look At Set-up B
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
Let us do the same thing for set-up B and observe all three factors first.
Let’s check the first one. Is there water in this set-up?
There is no visible water so you might think that this means water is absent. But that is incorrect.
💧 What Is Water Vapour?💧
There is water in the air, which is also known as water vapour.
So, we know that water is present in set-up B.
What about oxygen? If you look at this set-up, there is a substance that absorbs oxygen. Thus will there be any oxygen in this set-up? No.
You might be thinking, “But what about oxygen from the surrounding air? Isn’t there also oxygen there?”
Yes, there is oxygen in the surrounding air!
But this time, the container is covered by a plastic container. Are there any gaps between the plastic? No. As a result, can the oxygen or the air enter this container? The answer is no.
So, oxygen is absent.
What about warmth? Yes, there is warmth present but since oxygen is absent, do you think mould can grow on the orange?
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
No, so we can cross out set-up B.
Let’s Take A Look At Set-up C
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
For set-up C, we will also consider the three factors first.
Is there water present? Yes, and not only is there water vapour, it even has a container filled with water. So, we know water is present.
What about oxygen? How can we tell? If you look at set-up C, we can see there is wire mesh as well, allowing air or oxygen to enter. So, oxygen is present.
What about warmth? Warmth is also present. So, is set-up C possible? Yes!
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
Let’s Take A Look At Set-up D
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
Finally, for set-up D, let us check for the three factors (WOW).
Now, is there water in this set-up? Yes, there is water in the air, known as water vapour. So water is also present.
What about oxygen? Oxygen is also present. How can we tell?
Similar to set-ups A and C, there is also wire mesh so air can enter, which means oxygen is present.
What about warmth? Warmth is also present.
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
Comparing Set-ups C and D
What do we realise? Both set-ups C and D have all the conditions present. This means that mould would be growing on the orange in both set-ups.
But remember, the question is asking for the set-up where mould would first appear on the orange.
Let’s compare C and D. What difference can we see here? If you look at the conditions needed, do they both have the same amount of water? No, set-up C has more water.
Source: Methodist Girls’ School – 2020 P4 SA2 Examination Paper [Q6]
What about oxygen and warmth? Are they the same in both set-ups? Yes, so because of that, which set-up do you think the mould can appear first? It has to be set-up C.
Suggested Answer
Option (3).
Conclusion
I hope you have enjoyed reading this article and that this article has given you a recap on the three things that fungi need to grow — Water, Oxygen and Warmth (WOW).
Remember to keep practicing your past year examination questions and you will get better at tackling them.
Stay tuned for more exam paper analyses coming your way! 🙂
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