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COMMON BIOLOGICAL MISCONCEPTIONS 1

Common Biological Misconceptions

Laura P. Capps

Purdue University


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

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


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.


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).


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


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


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


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


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


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


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.


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

questionnaire for the simultaneous assessment of all aspects. International Journal of

Science Education, 28(4), 383-403.

Munson, B.H. (1994). Ecological Misconceptions. Journal of Environmental Education, 25(4),

30-34.


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.

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