Transwiki:Photosynthesis misconceptions


 * Student Misconceptions
 * The correct scientific explanation


 * Plants get most of their food from the soil. This is why fertilizers are needed.
 * Plants are autotrophs, meaning they create their own food from inorganic substances and energy. The Plant takes inorganic substances and water from the soil, not food.


 * The simple conversion of carbon dioxide and water to carbohydrates and oxygen is photosynthesis.
 * Photosynthesis is a complex series of reactions in which light energy is utilized to convert inorganic substances into carbohydrates. The oxygen released is a byproduct.


 * Photosynthesis occurs during the day, and at night, plants respire.
 * Photosynthesis includes the light reactions and the light-independent reactions. Both sets of reactions together comprise the suite of reactions that we refer to as "photosynthesis".  The requirement of light means that plants can only perform the full set of photosynthetic reactions during hours of the day when light is present.  The reactions of respiration have no such dependency on light, but the accessible chemical energy carried in the ATP produced during respiration is needed at all times—day and night—in order to power the living cells that constitute the plant.  Plants therefore must respire every second of their lives; when respiration stops, death begins.


 * Plants are green because they do not absorb green light.
 * Plants are green because their cells absorb other wavelengths of light more efficiently. Some green light is still absorbed, notably by accessory pigments rather than chlorophylls a and b.


 * Chlorophyll molecules in the light harvesting complexes transfer electrons to reaction centers.
 * Light energy is relayed into each of the photosystems. This energy reaches the chlorophyll a molecules in Photosystem II.  Electrons in the chlorophyll are excited into a higher energy state.  The excited electrons leave the chlorophyll a molecules.  The primary electron acceptor begins the electron transport chain.  Energy lost by electrons is used to move protons into the thylakoid.  Photosystem I electrons replace those that have passed through the electron transport chain in Photosystem II.  Electrons must be replaced in the system for the electron transport chains to continue functioning.

How can teachers help students to overcome these misconceptions?
Photosynthesis is one of the more difficult concepts taught in high school biology. There are definitely misconceptions that come with such broad and complex topics. The misconception mentioned above is one held by elementary, middle, and secondary students alike. Photosynthesis presents a difficult problem for educators since the molecules involved are so small, actually visualizing this process is difficult (Russell, 2004). The actual results of photosynthesis are also hard to analyze since plants grow at seemingly slow rates. Textbook diagrams have proved inadequate in addressing this misconception, but a new form of technology is promising. A group of researchers has developed “Photosynthesis in silico”, a multimedia exploration of photosynthesis and laboratory practices. The CD-Rom has separate modules for students to explore photosynthetic reactions. Because of the expense of laboratory equipment, the CD-Rom offers students a means by which to perform photosynthesis activities. After being tested, it was demonstrated that the use of such forms of multimedia eliminated over 70% of misconceptions. This tool represents a great way for teachers to educate their students in a cost efficient and highly effective manner. These interactive diagrams therefore seem imperative for students to understand the photosynthetic pathways.

Misconceptions are formed through five categories: oversimplifications, overgeneralizations, obsolete concepts or terms, misidentifications, and flawed research (Hershey, 2004). Many pre-service biology teachers are ill prepared to teach botany, and therefore they cannot readily recognize errors in literature and textbooks. Students’ misconceptions are then reinforced due to ignorance. Biology teachers must focus on these misconceptions in order to recognize when literature is incorrect (Hershey, 2004). The only way to overcome these misconceptions is to have teachers prepare more and have a more comprehensive analysis of what they are teaching.

The overall trend for eliminating misconceptions seems to be experiential learning and proper instruction. While the article by Russell does not outright say it, the CD-Rom is a form by which students can discover photosynthesis and experience it. The media used enables abstract ideas and concepts to come to life for students. Rather than imagining the electrons, students can visualize the movement of these particles. Furthermore, teachers need to understand misconceptions that students may have in order to help students overcome them. These are simply a few ways in which educators are assisting learners in their hunt for truth.