十週年教學分享
麥超強老師
Strategies dealing with students’
Misconceptions in Biology
Introduction
For students studying Biology, they always come across certain misconceptions in
the process of learning. It is therefore of utmost importance to understand the causes of
misconceptions and have these misconceptions clarified. In light of this, the author would
like to introduce some strategies in dealing with a common misconception that ‘the pollen
grains are the male gametes of the flowering plant’.
There are various reasons to choose the above misconception as the core example.
To begin with, in the topic of reproduction, there are always many terms and facts.
Generally, students just memorize the facts without proper understanding the structures of
pollen grains and the process of fertilization. In addition, the sizes of pollen grains are
extremely small that they are impossible to be observed unless microscope is used. What
comes as the consequence is that experiments concerning pollen grains are seldom
performed in lower form. Therefore, it is not surprising that many students may not have
a concrete idea about the nature of pollen grains.
Causes of misconceptions
1. Lack of prerequisite knowledge about the formation of male gametes:
Since the process of gamete formation in flowering plants is not required to study in
detail at lower form, students have no idea that each pollen grain consists of two male
gametes (nuclei). It is in fact, one male gamete will fuse with the egg cell to give a
diploid zygote while the other one will fuse with the polar nuclei to form the primary
endosperm nucleus. Thus in flowering plants, the process of fertilization is known as
‘double fertilization’, which is quite different from that of human beings.
Without the above prerequisite knowledge, students would wrongly think that pollen
grains are the male gametes. Whereas the fact is that pollen grains produce male
gametes.
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2. Informal preconception that pollen grains are similar to sperms in mammals:
In general, students have an incorrect analogy between anthers in flowering plants
and testes in mammals as follows:
TESTES
ANTHERS
 produce sperms  sperms are male gametes for
fertilization
 produce pollen grains  pollen grains are male gametes for
fertilization (wrong deduction)
In terms of similarities, both pollen grains and sperms are just numerous in
number and small in size. The similarities may sometimes make students
confused.
3. Informal preconception that pollination is similar to fertilization in plants:
Since students are not familiar with the process of fertilization in plants, they often
treat pollination as fertilization. As a result, fertilization is wrongly interpreted as the
transfer of pollen grains to the stigma. And pollen grains are wrongly expected as the
male gametes as well.
Strategies dealing with students’ misconceptions
1. Self deduction of right answers using questioning techniques
Without knowing the process of gametes formation in flowering plants, the role of
pollen grains can be explained simply as the carrier of male gametes by a number of
related questions:
Questions raised by the teacher
Expected response from students
1. What happens to the pollen grains
after pollination?
They just remain on the stigma.
2. Can the pollen grains fuse with the
female gamete?
No.
3. Do pollen grains represent male
gametes?
No.
4. What can be found inside the
pollen grains?
Two nuclei.
5. Does one of the two nuclei fuse
with the female gamete?
Yes.
6. What are the roles of the fused
nuclei ?
Male gametes.
7. What is the relationship between
Pollen grains are the carriers of male
pollen grains and male gametes?
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gametes.
2. Using cognitive conflict to distinguish between sperms and pollen grains
Students can be divided into groups to consider the following discrepant events:
(a) If pollen grains are the male gametes, what dangers will they face during
pollination?
(b) Why is that sperms as the true male gametes in mammals have no such
dangers at all?
(c) Now, do you consider pollen grains are equivalent to sperms?
After deep thinking on the above questions, students will come to the conclusions as
follows:
(a) If pollen grains are the male gametes, they will be exposed to air and
desiccation will be resulted during pollination. Thus, pollen grains play an
important role in protecting and carrying the gametes inside.
(b) Sperms in human are the real gametes but not well protected because no such
events as pollination and fertilization occur inside human bodies.
(c) Pollen grains are definitely not equivalent to sperms.
3. Making correct analogy between male gametes and female gametes of flowering
plants
Using the following comparisons, students will easily get the idea that pollen grains
are similar to ovules as both of them are carriers of gametes.
Male structure
Female structure
Stamen contains anther
Carpel contains ovary
Gives rise to
Pollen grains
Carry
Male gametes
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Gives rise to
Ovules
Carry
Female gametes
4. Using a concept map to link the processes of fertilization and pollination
Various concepts and ideas are linked together to give meaningful relationships
between the processes of fertilization and pollination. Students can thus understand
the knowledge without compartmentalization of concepts.
Anther
Produces
4 Pollen sacs
Produce many
Pollen grains
are transferred to
Stigma
Pollination
Pollen grains
After pollination
(1) outer layer of pollen grains
Remains on
Stigma
(2) male gametes
Carried by pollen
tube and reach
Ovary
Via micropyle
Ovule
Fuse with
Female gametes
Fertilization
In the above concept map, it clearly indicates that
(a) pollination and fertilization are two different processes
(b) pollen grains carry male gametes which will fuse with female gametes later.
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Conclusion
In studying Biology, it is obvious that some strategies are useful for students to deal
with their misconceptions. Of course, the above strategies and the cited example are for
reference only. There are still many strategies which can be applied with respect to
specific misconceptions in different topics
All in all, the main emphasis is that learning Biology is not such difficult once
students can develop their own strategies in dealing with their misconceptions. Through
these self-learning strategies, the author strongly believe that student would be able to
develop a critical and scientific mind in studying Biology.
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