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COMMON BIOLOGICAL MISCONCEPTIONS 1
Common Biological Misconceptions
Laura P. Capps
Purdue University
COMMON BIOLOGICAL MISCONCEPTIONS 2
Abstract
Science can be considered one of the more challenging subjects in school. The concepts
presented can often be contradictory to students’ previous perceptions and ideas. This paper
investigates those previous perceptions and ideas known henceforth as misconceptions. Firstly, I
will discuss two broad topic areas of biology and their respective subtopics under which many
misconceptions can be found. The two broad topic areas are ecology and biological energy. The
subtopics under ecology are food chains and webs, predator/prey relationships, adaptations,
carrying capacity, ecosystems, niche and the classification of plants. The subtopics under
biological energy are plant nutrition, photosynthesis and cellular respiration. This paper will also
discuss which age groups have these misconceptions, the sources of these misconceptions, the
reasons these misconceptions have persisted in the face of instruction and possible methods for
combating these misconceptions. Almost all of the information presented in this paper has come
from existing literature and studies conducted on this topic. Also presented in this paper are the
results of my own survey taken by thirty-one collegiate students currently enrolled in a biology
class for elementary school teachers, Biology 205, at Purdue University. The survey was also
taken by eight teaching assistants, who are former Biology 205 students who now teach the lab
sections of the class, the course coordinator, and the course professor. The survey was intended
to determine whether misconceptions still persisted even after instruction.
Keywords: biology, misconceptions, ecology, biological energy
COMMON BIOLOGICAL MISCONCEPTIONS 3
Common Biological Misconceptions
Introduction
“…The most important single factor influencing learning is what the learner already
knows. Ascertain this and teach him accordingly” (Larkin 2012 p. 927). This quote from David
Ausubel in his educational textbook, Educational psychology: A cognitive view (1968), is the
essence of misconceptions. Misconceptions are prior knowledge, thoughts, or beliefs that
contradict proven facts. These are especially prevalent in the field of science education. Students
come in to each science class with their minds already filled with ideas about how the world
works. The trouble is many of these ideas do not match the ideas found true by the scientific
community. In this paper, I will delve into two broad areas of biological content and some
specific subtopics in each area where many misconceptions have been identified. I will present
many of the common misconceptions in each area and then give the scientifically accepted
explanation of each misconception. I will also discuss some potential sources of misconceptions,
some reasons that these misconceptions persist even in the face of instruction and some methods
for combating these misconceptions and improving science education in general.
Misconceptions in Ecology
The first broad biological content area is ecology. Ecology is the study of living
organisms and the way they interact with each other and their environment. As I was conducting
my research, I came across three different subtopics of ecology where students were found to
have misconceptions: food chains, food webs, and ecosystems and associated content.
The first subtopic is food chains, a basic element of ecosystems. Food chains show
relationships between populations of producers and consumers from different trophic levels
(Gallegos, Jerezano & Flores, 1994). They are linear representations of feeding patterns, which
COMMON BIOLOGICAL MISCONCEPTIONS 4
begin with a producer and continue with different levels of consumers. Energy is passed from
each level of the food chain to the next, following a rule of energy known as the 10% rule. This
rule states that only 10% of the energy available at a given trophic level is available to the next
trophic level. Some students have difficulty understanding these concepts.
In a study conducted on fourth, fifth and sixth graders in a Mexican school system, it was
found that perception of “ferocity” and size of organism were the main criteria for an organism’s
placement in a food chain (Gallegos, et al., 1994). Students did not seem to understand that food
chains showed feeding patterns and needed to be based on the actual diets of the animals.
Instead, many students thought that if an animal was large, it was automatically a carnivore and
placed at the top of a food chain. Plants were correctly placed at the beginning of food chains but
the rationale was skewed. Instead of seeing plants as producers, many students identified them as
the smallest, weakest organism and therefore they belong at the beginning (Gallegos, et al.,
1994).
Students have also been found to hold false beliefs about the organisms at the top of food
chains. In contrast to the 10% rule, some students have been found to believe that organisms at
the top of food chains have the most energy because energy accumulates. As stated earlier, food
chains are governed by the 10% rule which directly contradicts students’ beliefs. Some students
also believe that “top” organisms are able to feed on all organisms below them on the food chain
and therefore deplete those species and give their own species a competitive advantage. These
beliefs are not in accordance with biological facts (Munson, 1994). Food chains are main
components of ecology and therefore biology, yet many students fail to comprehend the
principles on which they are constructed. The second subtopic is one that is closely related to
food chains: food webs.
COMMON BIOLOGICAL MISCONCEPTIONS 5
Food webs are complex diagrams that show the relationships between many different
organisms at various trophic levels. These are nonlinear representations that are composed of
multiple, interconnected food chains. This interconnectedness is one of the main ideas about
food webs that students have difficulty understanding. It has been found that students do not
comprehend that food chains and food webs are intricately related; food chains are the basis
upon which food webs are constructed. It has also been found that if students do understand that
food webs are made of food chains, they often fail to understand that each food chain is related
to the others. Food webs are not simply a mash-up of simple food chains, as many students
believe (Munson, 1994). They are a series of interconnected, interrelated food chains that are
linked to form a broader picture of the interactions between organisms in a given environment.
This is an idea that many students have difficulty accepting and understanding.
The third subtopic under ecology is ecosystems and the concepts that govern those
systems. Ecosystems are comprised of living organisms and the non-living components in an
environment. Ecosystems, by nature, are complex. There are multiple subtopics within this
subtopic as well. During my research, I found three that students have difficulty comprehending:
carrying capacity, populations and niche.
Carrying capacity is the idea that ecosystems only have a limited amount of resources and
can only sustain a limited number of organisms under ideal conditions. Many students falsely
believe that ecosystems have unlimited resources (Munson, 1994). It was also found that some
students acknowledge that resources are limited but only for animals. Some believed that plants
have unlimited resources. The truth is plants’ resources such as water, carbon dioxide and
minerals are just as limited as the food, water, and oxygen needed by animals (Munson, 1994).
COMMON BIOLOGICAL MISCONCEPTIONS 6
Populations are multiple individual, interbreeding organisms that live in the same
geographical area. In ecosystems, populations interact with each other all the time. Changes in
one population affect all other populations in the ecosystem. This is a concept not accepted by
many students. Students believed that only those organisms in a food chain or web with the
changed population will be affected by a change. Some students believed that changes in some
populations will have no effect on the ecosystem at all (Munson, 1994). All of these beliefs are
in opposition to scientifically accepted fact.
Niche is the idea that each species has its own unique needs, habitat and role in the
ecosystem. Some students either do not understand or are not aware of the idea of niche. They
generalize the needs of all species and believe that all species have the same needs and play
similar roles in the ecosystem (Munson, 1994). Ecosystems and their many components prove to
give students trouble and are full of misconceptions.
Misconceptions about Biological Energy
The second broad biological content area is biological energy. Biological energy is the
energy used by living organisms and found in ecosystems. It is passed from trophic level to
trophic level in food chains and webs. It includes the energy created by producers and used by all
organisms. Within this broad area, there are three subtopics of biological energy that I focused
on in my research: plants and plant nutrition, the process of photosynthesis, and the process of
cellular respiration.
Most students have been interacting with plants for the majority of their lives, inside and
outside of the classroom. However, there are still misconceptions about plants, especially about
where they get their food. There even are some misconceptions about what organisms are plants.
Some students believed that trees and grass were separate categories from plants. There were
COMMON BIOLOGICAL MISCONCEPTIONS 7
certain characteristics that the students believed all plants have: flowers, stems, leaves, green
color and roots that grow in the soil (Barman, Stein, McNair & Barman, 2006). Some students
identified fungi as plants because they have stems and were believed to create their energy from
the sun like plants do (Barman, et al., 2006). Plant nutrition is another topic where many
misconceptions are found.
The main misconception about plant nutrition is that plants obtain their food in similar
ways that humans do. That is, students do not understand that plants create their own food
internally and do not extract it from their environment (Treagust & Duit, 1995). Photosynthesis
and plant nutrition are not connected in the minds of many students. Another misconception that
students have is what actually constitutes food for plants. In a recent study conducted by me,
thirty-one college students enrolled in a biology course for elementary school teachers were
asked to identify what items were considered to be food for plants. Water, soil, sunlight and
fertilizer were chosen as food sources for plants as well as the actual food source of sugar. In
fact, sunlight was chosen nearly as often as sugar.
The second subtopic of biological energy is photosynthesis. Photosynthesis is a part of
plant nutrition but is more than that. Photosynthesis is the process by which plants use carbon
dioxide, water and sunlight along with the chlorophyll found within their leaves to produce
glucose (sugar) and oxygen. Many students fail to understand that photosynthesis is the process
by which plants produce their food. Some students believed that photosynthesis was plants’
versions of breathing (Keles & Kefeli, 2010). This thought led students to believe that
photosynthesis and cellular respiration cannot occur at the same time, a thought in direct
contradiction with scientific fact (Keles & Kefeli, 2010). Many students also fail to recognize the
role of photosynthesis outside of it being necessary for plants to live. This process is beneficial
COMMON BIOLOGICAL MISCONCEPTIONS 8
for all organisms because without photosynthesis, there would be a build-up of carbon dioxide
and a shortage of oxygen. Students do not realize that photosynthesis is necessary for all
organisms to live.
The third subtopic of biological energy is cellular respiration. Cellular respiration is the
process by which organisms use oxygen (most of the time) to break down sugars into a useable
form of energy. This energy is used by cells to carry out biological processes. The by-products of
this process are carbon dioxide, water and the energy released. It must be reiterated that the
process described above is cellular respiration, not organismal respiration. Organismal
respiration is the more commonly thought of process where carbon dioxide and oxygen are
exchanged through inhalation and exhalation. Students often times confuse the two processes
and believe that organismal respiration is the only kind of respiration. They believe that plants
inhale and exhale just like humans do (Canal, 1999). Other students have stated that plants do not
respire because they cannot inhale or exhale. These students forget about cellular respiration
(Keles & Kefeli, 2010). In some cases, students believed that, for plants, cellular respiration is
the inverse of photosynthesis. They believed that respiration occurs only at night when
photosynthesis cannot occur (Keles & Kefeli, 2010). The content area of biological energy is
complex and challenging and the subtopics of plants and plant nutrition, photosynthesis and
cellular respiration are three of the most difficult biological concepts for students to comprehend.
However, the misconceptions about these topics are ones that must be cleared up and set straight.
Survey
Most of the information in the above sections is information found from literature about
studies conducted by researchers and academics. I decided to conduct a survey of my own to see
if the misconceptions presented above are still found in the minds of college students. So I
COMMON BIOLOGICAL MISCONCEPTIONS 9
created a 14-question survey consisting of mainly multiple-choice with additional explanations
required for some questions. The questions were designed using the information found in the
literature and presented in the first three sections of this paper. I also used an article authored by
Panagiota Marmaroti and Dia Galanopoulou (2006) as a template for my questions. The survey
was voluntarily taken by thirty-one college students currently enrolled in a biology class for
elementary school teachers (Biology 205) at Purdue University, eight teaching assistants for the
same course, the course coordinator and the course professor. The results of this survey
confirmed that misconceptions that were found to be held by elementary and middle school
students were still found to be held by college students. The most interesting finding from this
survey was that all of the information in the survey was information that had been covered in
class, yet many of the participants answered the questions in manners that directly contradicted
the instruction given in class. This survey was an indication that misconceptions are not easily
eradicated. Students will hold onto their prior beliefs, sometimes in the face of instruction that
directly contradicts the prior beliefs.
Sources of Misconceptions
There are multiple sources of the misconceptions described above. Students’ perceptions
and ideas about biology can be influenced by many different things and people. Going back to
the quote at the beginning of this paper, the major source for misconceptions is the students’
prior knowledge. This knowledge could be observations from daily life, past experiences,
solutions for everyday problems or false information taught by peers or family members
(Treagust & Duit, 1995). Often times, students will observe something and formulate their own
explanation about why certain things happened. For example, students may observe that a plant
is not growing well. So students will add sunlight, water, or fertilizer like Miracle Gro®. The
COMMON BIOLOGICAL MISCONCEPTIONS 10
plant begins to grow better and students falsely conclude that the sunlight, water or fertilizer is
food for the plant and that’s why it grew. Once these conclusions are formed, it is very difficult
for instruction to change them.
Everyday language and mass media are also sources for misconceptions. Students often
apply common language to scientific concepts (Treagust & Duit, 1995). For example, the word
“respiration” is often only thought to mean the exchange of oxygen and carbon dioxide through
inhalation and exhalation. Students do not remember that respiration has another scientific
meaning: cellular respiration. Language is also a part of mass media and the advertising industry.
Right on the label for Miracle Gro® fertilizer is the words “Plant Food” and in the ad campaign,
the company claims their product “feeds plants up to 6 months” (The Scotts Company LLC,
2012). This type of language and advertisement gives the impression that fertilizer actually is
food for plants when it is not.
Reasons for Longevity
One of the simplest reasons these misconceptions persist in the face of instruction is
because students are quite satisfied with their own explanations (Treagust & Duit, 1995). In their
minds, based on what they have seen or learned from other sources, those explanations make
sense; they see no need to change them. In many cases, students will learn the information for a
test or quiz in school and then revert back to old familiar thoughts. This was also indicated in my
own survey. Even though the information had been taught in class and students had been tested
over the material, many students were not able to recall the information. This could be because
students had memorized the information and had recalled the information for the test. After the
test, they gave no more thought to it. The information had not been processed or analyzed, and
COMMON BIOLOGICAL MISCONCEPTIONS 11
therefore it did not stick in their minds. Older, more familiar conceptions were able to creep back
in.
Ways to Combat Misconceptions and Improve Science Education
It is clear that misconceptions are difficult to change; however it is not an impossible
task. One way to help students understand the differences between what they think is true and
what is actually true is to challenge their misconceptions (Treagust & Duit, 1995). There are
three approaches in this method, continuous, discontinuous and constructivist. A continuous
approach is a slower approach that starts with aspects of the misconception that are close to
actual scientific fact and breaks them down. The misconception is replaced by fact, bit by bit. A
discontinuous approach is a more aggressive approach where instructors create situations that
directly contradict students’ misconceptions (Treagust & Duit, 1995). There are conflicts created,
between the teacher and students, students and their beliefs, or students and other students
(Treagust & Duit, 1995). A constructivist approach includes discussion and exploration of ideas
through experimentation. The idea behind this approach is that ideas can be “clarified,
reconstructed, or challenged” through discussions that compare and contrast students’ ideas and
scientifically accepted ones (Treagust & Duit, 1995). In each one of these approaches, the main
thing to remember is that students’ misconceptions must be acknowledged and must be the
starting point for instruction. By doing this, science education, as a whole, can be improved.
Conclusion
“…The most important single factor influencing learning is what the learner already
knows. Ascertain this and teach him accordingly” (Larkin 2012 p. 927). This is the quote that
began this paper and is a fitting one to close it. As discussed in this paper, there are many things
in the field of biology that students think are true. However, many of these misconceptions
COMMON BIOLOGICAL MISCONCEPTIONS 12
directly contradict accepted scientific knowledge. It is a challenge in science education to change
students’ prior false knowledge, especially because students are quite content with their own
ideas. While it is challenging, changing the misconceptions is necessary. The best way to do that
is to do just as David Ausubel said: start with what students know and go from there.
COMMON BIOLOGICAL MISCONCEPTIONS 13
References
Barman, C.R., Stein, M., McNair, S., & Barman, N.S. (2006). Students’ Ideas about Plants &
Plant Growth. The American Biology Teacher, 68(2), 73-79.
Canal, P. (1999). Photosynthesis and ‘inverse respiration’ in plants: an inevitable
misconception?. International Journal of Science Education, 21(4), 363-371.
Gallegos, L., Jerezano, M.E., & Flores, F. (1994). Preconceptions and Relations Used by
Children in the Construction of Food Chains. Journal of Research in Science Teaching,
31(3), 259-272.
Keleş, E., & Kefeli, P. (2010). Determination of student misconceptions in “photosynthesis and
respiration” unit and correcting them with help of cai material. Procedia Social and
Behaviorial Sciences, 2, 3111-3118.
Larkin, D. (2012). Misconceptions About “Misconceptions”: Preservice Secondary Science
Teachers’ Views on the Value and Role of Student Ideas. Science Education, 96(5), 927-
959.
Marmaroti, P. & Galanopoulou, D. (2006). Pupils’ Understanding of Photosynthesis: a
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Science Education, 28(4), 383-403.
Munson, B.H. (1994). Ecological Misconceptions. Journal of Environmental Education, 25(4),
30-34.
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The Scotts Company LLC. (2012). Miracle-Gro® Potting Soil Home Page. Retrieved from:
http://www.scotts.com/smg/catalog/productTemplate.jsp?
proId=prod70332&itemId=cat50154
Treagust, D. F., & Duit, R (1995). Students’ Conceptions and Constructivist Teaching
Approaches.. In B.J. Fraser & H.J. Walberg (Eds.), Improving Science Education (pp. 46-
69).Chicago, IL: The National Society for the Study of Education.