Do you like to eat grapes? 🍇
If your answer is “yes”, I am sure you would have noticed that some of the grapes that you have eaten are bigger and juicier than usual, just like the ones shown below.
Have you then wondered how some farmers are able to attain fruits that are bigger and juicier than usual? 🤔 I shall briefly share with you the various methods that can be used to attain bigger and juicier fruits.
Method #1: Pruning
Pruning is the removal or reduction of plant parts (branches, buds, withered flowers etc) that are detrimental to the development of the plant. Doing so helps to improve fruit size and quality.
Method #2: Genetic Modification
Genetic modification is the process of identifying the genetic information that allows for the production of bigger fruits. Once identified, that genetic information will be inserted into other plants for them to produce bigger fruits.
Method #3: Girdling
Girdling is the process where only the food-carrying tubes are removed around the entire circumference of the stem of a plant. Doing so can also allow bigger fruits to be produced.
Most of you might not be familiar with methods #1 and #2 above (pruning and genetic modification) as they are not in the primary school Science syllabus.
As for method #3 above, you might not have seen the term “girdling” in your school examination papers. However, most of you should have come across school examination questions that require you to explain what happens to the plant when only the food-carrying tubes are removed (which is essentially the process of girdling)!
So, what happens to the plant after the process of girdling? Let us have a closer look at 2 questions from the 2018 Red Swastika School (RSS) P5 CA1 and 2016 Rosyth School (ROSYTH) P5 CA1 Examination Papers.
Read Also:
Let’s Take A Look At This Question
Source: Red Swastika School (RSS) – 2018 P5 CA1 Examination Paper [Q31]
In order to explain what happens to the plant when the water-carrying tubes and/or food-carrying tubes were removed/were still intact (just like the question above), you will only need to follow 3 simple steps to craft a complete answer.
🥅 3 Steps
1️⃣ What tubes were removed/were still intact?
2️⃣ What substance cannot be transported/can still be transported?
3️⃣ Explain the outcome.
Using the 3 steps above, let us try and answer the question:
“Explain why the swelling occurred at position A of the stem.”
Thought Process
Since this question has already mentioned the outcome that swelling occurred at position A of the stem, let us work backwards by first explaining the reason for the outcome of swelling (step 3), before clarifying what substances could not be transported (step 2), and then finally identifying what tubes were removed/were still intact (step 1).
Step 3: Explain the outcome
“Why does swelling of an object take place?”
Swelling takes place due to an accumulation of substances inside the object, just like how the balloon starts swelling up when more air is blown and accumulated inside it!
“For swelling to occur at position A of the stem, what substance do you think was accumulated at position A of the stem?”
Should it be food or water? If your answer is food, you are correct!
Answer: Food was accumulated at position A of the stem, causing it to swell.
Step 2: What substance cannot be transported/can still be transported?
“Since food was the substance accumulated at position A of the stem, what should be the substance that cannot be transported past the cut?”
Food made by the leaves during photosynthesis must be the substance that cannot be transported past the cut.
“Since food was accumulated above the cut (position A), did the food come from the leaves above or below the cut?”
The food should have come from the leaves that are above the cut, where the food cannot be transported past the cut down to the roots and will accumulate at position A of the stem.
Answer: Food made by the leaves above the cut during photosynthesis could not be transported past the cut down to the roots.
Step 1: What tubes were removed/were still intact?
“Since we have identified from step 2 above that food made by the leaves cannot be transported past the cut, which tubes must have been removed? Were the food-carrying tubes or the water-carrying tubes removed?”
The food-carrying tubes must have been removed.
“How about the water-carrying tubes then? Were they removed at the cut?”
Once again, from step 2 above, since we have identified that the leaves above the cut were able to make food, should the leaves above the cut be able to receive water from the roots? The answer is “yes” since water is needed for the leaves to make food.
“Since water absorbed by the roots could still be transported upwards past the cut to the leaves above the cut to make food, were the water-carrying tubes removed/intact?”
The water-carrying tubes must still be intact and only the food-carrying tubes were removed.
Answer: Only the food-carrying tubes were removed at the cut.
🎋 Tip: Whenever swelling occurs, it’s only the food-carrying tubes that would have been removed.
If we put all the above 3 steps together, this is what our answer will look like:
Suggested Answer
Only the food-carrying tubes were removed at the cut (step 1). Food made by the leaves during photosynthesis above the cut could not be transported past the cut down to the roots (step 2). Thus, food will be accumulated at position A, causing that part to swell (step 3).
At this point, I know what some of you must be thinking:
“Why would anyone remove the food-carrying tubes of a plant?”
As mentioned at the start of the blog post, it is common for farmers to carry out the process of girdling, where only the food-carrying tubes are removed to obtain bigger fruits.
However, the MOST IMPORTANT question is:
“How does removing only the food-carrying tubes lead to bigger fruits?”
To answer the above question, let us look at another question.
Moving On To Another Question
Source: Rosyth School (ROSYTH) – 2016 P5 CA1 Examination Paper [Q18]
Thought Process
The key information from the question is:
“The food-carrying tubes at part X were removed.”
As a result, what tubes are still intact at part X?
Answer: Water-carrying tubes
Since the water-carrying tubes are still intact at part X, can the water absorbed by the roots still be transported past the cut to the leaves at part A (refer to the picture below)?
Definitely. As a result, are the leaves at part A still able to receive water for photosynthesis to make food?
Answer: Yes
However, here comes the important question that we have to clarify:
“Can the food made by the leaves at part A during photosynthesis be transported past part X downwards to the roots?”
Since the food-carrying tubes were removed at part X…
Answer: No
“If the food made by the leaves at part A can no longer be transported to the roots, where will they be transported to instead?”
The food made by the leaves at part A that was supposed to be transported to the roots would be transported to the fruits to be stored instead.
Answer: To the fruits
“As a result, after the food-carrying tubes are removed at part X, will there be more food or less food transported to the fruits to be stored?”
Answer: More
“And since there is more food stored in the fruits, are we going to obtain bigger fruits or smaller fruits?”
Answer: Bigger fruits
Based on the thought process above, we can follow the same 3 steps introduced at the start of the blog post to craft our answer.
🥅 3 Steps
1️⃣ What tubes were removed/were still intact?
2️⃣ What substance cannot be transported/can still be transported?
3️⃣ Explain the outcome.
Suggested Answer
At part X, only the food-carrying tubes were removed (step 1). Food made by the leaves during photosynthesis cannot be transported past the cut down to the roots (step 2). Thus, more food will be transported to the fruits to be stored, causing the fruits to become bigger (step 3).
With the suggested answer above, I hope I have clarified how the method of girdling (removing only the food-carrying tubes) helps the farmers to attain bigger fruits!
However, I would now like all of you to put on your thinking caps to answer a bonus question with regard to the same scenario:
Bonus Question
Since we have discussed that the food made by the leaves at part A (refer to the diagram above) cannot be transported to the roots, will the roots die in the long run?
Notice that other than the leaves at part A, there are also leaves at part B. Referring to the diagram above, just beside the leaves at part B, were there any tubes of the stem removed? No.
As a result, are the leaves at part B able to receive water to make food? Yes. Can the food made by the leaves at part B be transported down to the roots as well? Definitely. As such, will the roots still be able to receive food? Yes!
Since the roots can still receive food from the leaves at part B for respiration to release energy, can the roots still survive in the long run?
Answer: The roots can still survive in the long run.
Conclusion
After reading this article, I hope that you have gained more confidence to tackle application questions related to the removal of food-carrying tubes.
Do remember to follow the 3 steps below if you are required to explain the outcome for the plant after:
- Only the food-carrying tubes were removed.
OR
- Both the food-carrying tubes and water-carrying tubes are removed.
🥅 3 Steps
1️⃣ What tubes were removed/were still intact?
2️⃣ What substance cannot be transported/can still be transported?
3️⃣ Explain the outcome.
Stay tuned for our upcoming articles on how to tackle other Science questions!
If you like our methodology, we've some upcoming workshops:
