Introduction
How are the concepts of food-carrying and water-carrying tubes tested in your Science examinations?
Besides knowing the functions of these tubes, you also need to know how the removal of these tubes can affect the plant, which is a commonly tested scenario in your Science examinations.
To help you understand how to tackle such challenging questions, I will be analysing an examination question on Transport in Plants from the 2017 Anglo-Chinese School (Junior) (ACSJ) P5 SA1 Examination Paper.
Let’s Take A Look At Part (A)
Source: Anglo-Chinese School (Junior) (ACSJ) – 2017 P5 SA1 Examination Paper [Q32]
Read Also:
Thought Process
To help us answer part (a), we need to find out where substance X is coming from.
Based on the diagram, are you able to identify the source of substance X? If you said the leaves, you are absolutely right!
Substance X must be made by the leaves and is then transported to the stem, and then to all parts of the plants, including the roots.
What is the substance produced by the leaves?
Think about the function of the leaves. The leaves would be able to carry out photosynthesis to make food.
Thus, Substance X is likely to be food!
There are also alternative answers. We can write sugar or even glucose, which are terms that can also be used to represent the food made by the leaves during photosynthesis.
Suggested Answer For Part (A)
Food/Sugar/Glucose
Moving On To Part (B)
“Based on the diagram above, explain why the part of the trunk became swollen.”
Source: Anglo-Chinese School (Junior) (ACSJ) – 2017 P5 SA1 Examination Paper [Q32]
Thought Process
When the trunk becomes swollen, there is an accumulation of a certain substance.
🍃 What is the substance accumulated in the trunk?🍃
Food is accumulated causing the trunk to swell.
The next thing we need to explain is why is there food accumulated at that particular part of the trunk. Think about where the food is being made.
In part (a), we established that food is made by the leaves. After that, the food made by the leaves will be transported to the stem and the rest of the plant, including the roots. What must have happened was that food made by the leaves was transported downwards towards the stem.
📌 Could food be transported past the destroyed bark? 📌
The answer is no. If there was food accumulated above the destroyed part, that means that the food was not able to be transported past the destroyed part.
Something must have been removed from the destroyed bark but that prevents food from being transported.
What can you find inside the bark of the stem of the plant? You can find food and water-carrying tubes!
When the ring of bark was bitten off by pests, the food-carrying tube must have been removed. When the food-carrying tube was removed, any food that was made by the leaves could not be transported past the destroyed bark. Thus, food was accumulated above the destroyed bark, causing the trunk to swell.
What About The Water-Carrying Tubes?
The roots of the plant absorb water.
If the water-carrying tube was removed, would water be able to reach the leaves?
The answer is no.
If the water-carrying tubes were removed, water would not be able to reach the leaves above the destroyed bark.
If the leaves cannot receive water, they will not be able to make food. But in this scenario, we have food accumulated in the trunk. This means that the leaves must be able to make food. Thus, the water-carrying tubes must not have been removed and must have remained intact!
We can conclude that only the food-carrying tubes were removed.
When it comes to Transport in Plants questions, there must be a few key phrases that are present in your answer.
🎋 Guiding Questions To Formulate Transport In Plants Answers 🎋
- What are the tubes being removed?
- Was food or water able to be transported past the part of the stem that has been removed?
- What happens when food or water could not be transported past the part of the stem that has been removed?
Following the three guiding questions above, this is how we will phrase our answer:
Suggested Answer For Part (B)
The leaves of the apple tree trap sunlight for photosynthesis to make food. The food was then transported to all parts of the tree through the food-carrying tubes. However, the food-carrying tubes were bitten off by pests, and food made by the leaves could not be transported past the ring to the roots, thus the food accumulated above the ring, causing that part of the trunk to become swollen.
Conclusion
After reading this article, I hope that you have gained a better understanding of how the concepts of food-carrying and water-carrying tubes can be tested in application questions.
I have also covered three guiding questions to help you craft a complete answer for open-ended questions from the topic of Transport in Plants so that you can gain full marks for them!
Stay tuned for our upcoming articles on how to tackle other challenging Science questions!
If you like our methodology, we've some upcoming workshops:
