Reproduction in Plants
Seed Dispersal Diagram
Take note of the science knowledge and how they are applied to the science exam questions.
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To do well in this topic, we need to memorise the plant parts and their functions.
I’ve provided a few examples of the proper answering techniques for each seed dispersal method.
As always, understand how the plant parts and functions are used in the science open-ended questions.
Explain how is the Shorea fruit dispersed by the wind?
Plant part: Shorea fruit has wing-like structures.
Function: This increases the surface area and air resistance for the fruit to stay afloat in the air longer. The fruits are dispersed further away from the plant by the wind.
Combined answer: Shorea fruit has wing-like structures which increase the surface area and air resistance for the fruit to stay afloat in the air longer. The fruits are dispersed further away from the plant by the wind.
Explain how is the coconut fruit is dispersed by the water?
(Note: You can use any one of the characteristics)
Plant part: Coconut fruit has a fibrous husk.
Function: Fibrous husk traps air and enables the fruit to float on water.
Combined answer: Coconut fruit has a fibrous husk that traps air and enables the fruit to float on water. This enables the fruit to be dispersed by water.
Take note of this common mistake
Coconut fruit has a fibrous husk that enables the fruit to float on water.
Teachers’ comments: You need to provide the function of the fibrous husk which is to trap air.
Identify the method of dispersal for the saga fruit. Explain your answer.
Explosive action or splitting action
Plant part: Seed pods
Function: They split along the lines of weakness. The seeds inside are then flung out with force, dispersing the seeds by explosive action.
Combined answer: Explosive action or splitting action. Seed pods split along the lines of weakness. The seeds inside are then flung out with force, dispersing the seeds by explosive action.
We don’t recommend this answer:
Some students wrote “Seed pods split along the lines of weakness. The seeds inside are then dispersed by explosive action”
Do include the “seeds inside are then flung out with force” to more accurately explain how the seeds are dispersed by explosive action.
Identify the method of dispersal for the kiwi fruit. Explain your answer.
(Note: There are two plant parts and two functions)
Seeds of the kiwi fruit are dispersed by animals.
Plant part: fleshy fruit
Function: This attracts the animals to eat the fruit.
Plant part: Small, undigestible seeds
Function: Animals move away from the parent plant and passed out the undigestible seeds as droppings.
Combined answer: Seeds of the kiwi fruit are dispersed by animals. It has fleshy fruit to attract animals. Animals eat the fruit and the small, undigestible seeds. Animals move away from the parent plant and passed out the undigestible seeds as droppings.
Let’s apply the scientific knowledge by answering this question!
The diagram below shows the fruit of plant A and plant B respectively.
The diagram below shows the growth of the seedlings of two parent plants.
Based on the information above, what is the method of dispersal of plant A? Explain your answer.
STEP 1
Identify the pattern in which the seedlings are dispersed from the parent plant.
The seedlings of plant A are scattered randomly around parent plant A.
STEP 2
Identify the method of dispersal based on the pattern in which the seedlings are dispersed.
Scattered randomly around the parent plant are dispersed by animals
Note that the direction of the wind is to the right, meaning that seedlings of a plant dispersed by wind would grow along the direction of the prevailing wind. However, the seedlings of plant A are growing on both the left and the right of the parent plant. Hence, plant A cannot be dispersed by wind.
STEP 3
Explain how the identified method of dispersal is carried out. Link this back to the pattern in which the seedlings are dispersed.
Plant part: fleshy fruit of plant A.
Function: This attracts the animals to eat the fruit.
Plant part: Small, undigestible seeds of fruit A.
Function: Animals move away from the parent plant A and passed out the undigestible seeds as droppings.
FINALLY, put your answer together
Question: What is the method of dispersal of plant A? Explain your answer.
Answer:
Seeds of plant A are dispersed by animals
Evidence: The seedlings of plant A are scattered randomly around parent plant A.
The fleshy fruit of plant A attracts the animals. The small, undigestible seeds of fruit A are eaten by the animals. Animals then move away from the parent plant A and passed out the undigestible seeds as droppings.
Why do we need to provide the evidence for this question?
In step 1, we are determining the method of dispersal. How did we know seeds of plant A are dispersed by animals? We analyse the seed dispersal patterns from the diagram.
Hence, to communicate effectively with the examiner, we are required to provide the evidence found in the diagram!
Common mistakes
- Incomplete explanation: Animals ingest the fruits and disperse them.
It is unclear how the animals disperse the fruits after ingesting them. Hence, you need to specify that animals ingest the indigestible seeds along with the fruits, then explain how the animal releases these seeds away from the parent plant.
- Incomplete explanation: Animals eat the seeds and pass them out in their droppings.
This is incomplete for two reasons:
- Firstly, you need to specify that the seeds are undigestible. This explains how the seeds can be released in droppings.
- Secondly, you need to specify that the animals move away from the parent plant. This explains how the seeds can be dispersed away from the parent plant.
Incorrect phrasing: The seeds are pooped out.
This is not a scientific way of explaining the concept. You need to use scientific words, such as droppings or faeces.
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Andy Ling
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