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Welcome back to our Examination Paper Analysis series!
In this article, we will be reviewing the 2018 Nan Hua Primary School (NYPS) P5 SA1 Science Examination Paper.
What Topics Are Covered In This Paper?
After reviewing both Booklets A & B in this paper, I discovered that the two main topics with the highest weightage are Reproduction In Plants (7 questions) and Body Systems (6 questions). I have also compiled the topics tested in the table below:
While this examination placed heavier emphasis on Reproduction In Plants and Body Systems, my students found those questions rather straightforward, and most did not face issues in getting the right answers.
Hence, I have identified 2 questions to review in this article from the topics of Cells and Heat Energy that more students struggled with.
Let’s Take A Look At Q9
Source: Nan Hua Primary School – 2018 P5 SA1 Examination Paper [Q9]
At first glance, the question seems overwhelming due to the amount of information provided. My advice to students is not to panic and start by breaking down the question bit-by-bit. Here’s a step-by-step guide to analysing this question!
Step 1: Identify Keywords/Keyphrases in the Question
Janice conducted an experiment using bags made of two different materials. She poured a mixture of starch and water into the bags and left them in beakers of water with iodine solution. Iodine solution turns dark blue when it comes into contact with starch.
Step 2: Breaking Down the Keywords/Keyphrases
- “two different materials”
- Recall that different materials have different properties.
- “Iodine solution turns dark blue when it comes into contact with starch.”
- Iodine solution is a test for the presence of starch. For those of you who have forgotten what starch is, excess food made by the leaves of a plant during the process of photosynthesis is converted into starch and stored in the plant. This process is very similar to when excess digested food in our bodies is converted to fats and stored. In other words, the starch in plants is similar to the fats found in our bodies!
- The question states that “Iodine solution turns dark blue when it comes into contact with starch”. This begs the question – what is the original colour of the iodine solution?
Answer: Iodine solution has a yellowish-brown colour in the absence of starch.
Have you ever wondered why there is a need for scientists to carry out the starch test?
The starch test is used to determine if photosynthesis has taken place. The reason why scientists test for starch instead of glucose (sugar/food) is because the glucose produced by the plant will be rapidly converted to starch for storage.
Step 3: Relating the Diagram to the Science Concepts Taught
As I’ve encountered questions with similar set-ups in other examination papers, the first thing that I will take note of is the movement of substances through the bags. However, students encountering this type of set-ups for the first time may not be able to fully analyse the information provided and apply the Science concepts they’ve learnt appropriately.
Let’s take a look at data from Set-Up A together:
ANALYSING SET-UP A
Based on the conclusion above, we can observe that there was a movement of substances through the bag. The iodine in the beaker was able to enter the bag but the starch was unable to exit the bag. Hence, the starch was unable to come into contact with the iodine solution outside the bag which resulted in the water with iodine solution remaining brown. This shows that the bag in Set-Up A was able to control the movement of substances passing through it.
How does this relate to the plant cell? Let’s recall the cell part that also has the function of controlling the movement of substances. If you are thinking of the cell membrane, you are right! The plant cell contains a cell membrane, which controls the movement of substances in and out of the cell. As such, the function of the bag can be related to the function of the cell membrane.
In secondary school, we say that the cell membrane is “partially permeable”. (Permeability is the ability of substances to pass through a material.)
What about the data from Set-Up B?
Based on the conclusion above, we can also observe that there was a movement of substances through the bag. The iodine in the beaker was able to enter the bag and the starch was able to exit the bag. This shows that the bag in Set-Up B was not able to control the movement of substances passing through it. Which cell part could the bag in Set-Up B represent?
If your answer is the cell wall, you are absolutely right! The cell wall gives the cell a regular shape and prevents the cell from bursting. However, the cell wall does not have the ability to control the movement of substances in and out of the cell.
In secondary school, we say that the cell wall is “fully permeable”.
Now that we understand the set-ups, let us move on to the next diagram.
Are you able to identify Parts X, Y & Z and recall their respective functions?
Based on our conclusions earlier, the bag in Set-up A has control over the movement of substances through the bag, which is similar to the Cell Membrane (Part Z). On the other hand, the bag in Set-Up B does not control the movement of substances through the bag, which is similar to the Cell Wall (Part Y).
Now, let’s take a look at the options given again.
As discussed, based on our conclusions, the answer is Option (3).
Let’s Take A Look At Q40a
Source: Nan Hua Primary School – 2018 P5 SA1 Examination Paper [Q40a]
When we are having a fever, we will usually place a wet towel, ice pack or fever patch to help our body cool down. What is the science behind this?
Our body becomes warmer than usual when we are having a fever. By placing a wet towel, ice pack or fever patch that is cooler on our body, there will be a transfer of heat away from our body. Why is that so?
Think of the following property of heat that you have learnt:
“Heat always travels from a warmer region to a cooler region”.
Since our body is warmer than the wet towel, ice pack or fever patch, our body will lose heat to them thus helping to cool our body down!
In this question, we need to choose a substance that is most suitable to be used in an ice pack to apply to a child who is having a fever. The first thought that came to many students was:
“Since the purpose of the ice pack is to cool the child’s warmer body down, I should choose the ice pack of the lowest temperature, hence, Substance Y must be the answer!”
If you had the same thought process, this is actually a misconception! We cannot determine the answer just by looking at the final temperature of the substance after heating. Let’s find out why!
When the four substances were heated for 10 minutes, their temperatures all increased, however, we observe that the temperatures recorded were not the same. What does this tell us? This tells us that the four substances did not gain heat from the candle flame at the same rate and have different heat conductivities. (Heat conductivity is the ability to transfer heat.)
- A good conductor of heat would allow heat to pass through it quickly.
- A poor conductor of heat would allow heat to pass through it slowly.
In order to learn more about the heat conductivities of the four substances, let’s calculate the increase in temperature for all of the substances below:
Let’s take Substance Y as an example. After heating for 10 minutes, the increase in temperature of Substance Y is 5°C, which is the least amongst the four substances. This means that Substance Y gains heat the slowest from the candle flame and is the poorest conductor of heat.
Imagine using an ice pack that gains heat the slowest from your body when you are having a fever. Do you think that this would be effective in cooling your body down? No, your body would still be rather warm from the fever due to the slow rate of heat transfer from your body to the ice pack! Hence, Substance Y is not the most suitable to be used in the ice pack.
At this point, I am sure that you are aware of the following:
- The most effective ice pack should contain the substance that helps your body to cool down the fastest.
- We should choose the substance to be used in the ice pack based on its heat conductivity and NOT based on its final temperature after heating.
As we have already established, the most effective ice pack should contain the substance that helps our body to cool down the fastest. Hence, we should be looking for the best conductor of heat!
Looking at the recorded results again, are you able to figure out which substance is the best conductor of heat?
If you are thinking of Substance Z, you are right!
Substance Z has the greatest increase in temperature after being heated for 10 minutes, which shows that Substance Z gained heat the fastest from the candle flame. This shows that Substance Z is the best conductor of heat and is the most suitable to be used in the ice pack.
To answer the question more effectively, I have taught my students to use the CUE (Choose, Use Data, Explain Data) answering technique to avoid missing any key points in their answers.
Choose: Substance Z.
Use Data: The temperature of Substance Z after 10 minutes was the highest.
Explain Data: This shows that Substance Z gained heat the fastest from the candle flame and is the best conductor of heat. Thus, heat from a child who is having a fever would be lost to the ice pack with Substance Z the fastest, cooling the child down the fastest [link back to the purpose of object].
*Tip: REMEMBER to link back to the purpose of the object for a more complete answer*
I hope that you have enjoyed reading this article and that you are now able to:
- Identify & break down the keywords/keyphrases given in the question.
- Relate the diagrams to the Science concepts taught.
- Understand that the substance used in the ice pack should be chosen based on its heat conductivity and not its final temperature after heating.
- Remember to link your chosen answer back to the purpose of the object for a more complete answer.
We have come to the end of the examination paper analysis of 2018 Nan Hua Primary School (NYPS) P5 SA1 Science Examination Paper.
Stay tuned for more exam paper analysis coming your way! 🙂