Misconceptions in

Biology

Misconceptions can kill you. One common misconception is “if a little is good, more is better”. A little medicine, pain killer, or sedative can relieve symptoms, but too much may cause complications and even death. For example, an excess of sleeping pills (barbiturates) has lead to the death of many celebrities including rock and roll stars Elvis Presley, Jimi Hendrix, and Brian Jones (Rolling Stones) and movie star Marilyn Monroe.

Many misconceptions are propagated because they seem logical. For example, many believe that you can treat frostbite (injury to fingers, toes, ears and other body tissues due to exposure to extreme cold) by drinking alcohol, smoking cigarettes and not drinking water. This seems logical since alcohol makes one feel warm, cigarettes bring hot air into the lungs, and water is generally cool. However, medical experts say that alcohol reduces shivering (the body’s way of generating friction to keep tissues warm), nicotine (the addictive substance in tobacco) slows circulation, and dehydration (insufficient body water) reduces blood flow to endangered tissues. Thus, when suffering frostbite, a person should drink water, but should not smoke or drink alcohol.

The following are a few common misconceptions in biology. For each, we have introduced contradictory data from which one may reason to disprove the misconception.

misconception: Cold, wet weather causes the flu.

contradictory data: Influenzas are caused by viruses. Viruses live and reproduce within the cells of host organisms, not within cold, wet rain.

correct explanation: People believe that cold, wet weather causes the flu because people often get sick during this type of weather. It is true to say that the influenza is correlated with this type of weather, but incorrect to say that it is caused by it. People tend to stay inside more during this type of weather, and are more likely to come in contact with others who are infected. Although the weather does not cause the flu, it should be noted that people may be more susceptible if they are chilled.

misconception: Plant mass comes from the water and minerals plants obtain from the soil.

contradictory data: One would expect plants to sink into the soil if their entire mass was drawn from the minerals and water withdrawn from the soil. However, one does not find depressions around trees or bushes, suggesting that this explanation is flawed.

correct explanation: Although plants do absorb and retain water and minerals from the soil, the majority of plant mass is made of cellulose and other carbon-based molecules. Most plant mass is obtained from atmospheric carbon dioxide as carbon is fixed into sugars during the process of photosynthesis.

misconception: People use only ten percent of their brains.

contradictory data: Positron emission tomography (PET-scan) and functional magnetic resonance imaging (fMRI) shows activity in all parts of the brain, although not simultaneously.

correct explanation: The 10% myth is frequently quoted by “psychics” and other who exploit people’s ignorance and offer ways of tapping into the "unused 90%" of the brain. We use different portions and pathways of the brain for different functions, so it is impossible to say precisely what percent of the brain we use at any time.

misconception: Only meat, fish, and eggs have protein.

contradictory data: DNA is transcribed to RNA, which is translated into proteins. All life is based upon DNA, therefore all living systems must produce proteins.

correct explanation: All cells manufacture protein. Proteins provide structure and serve as enzymes and hormones essential for biological processes. Certain foods have a higher percentage of proteins than other foods. For example, meats have a high percentage of proteins because they come from muscular tissue that is composed primarily of two proteins, actin and myosin.

misconception: There is a start and an end to the food chain.

contradictory data: If this were true, all nutrients would end up at the end of the food chain and there would be none available for new life.

correct explanation: Decomposers, primarily fungi and bacteria, breakdown all life forms, including those at the top of the food web, and return nutrients to the soil, water and air where they are used by primary producers. If there were no decomposers, than the vast majority of carbon and other nutrients would be locked up in dead organisms and unavailable for further life.

Activity 7.6.1 – Clarifying misconceptions in biology

Note to teacher: The following is a list of common misconceptions in biology. Give one to each student and instruct them to research the misconception, explain why it is wrong by reasoning from observed facts and experiences, and provide a correct explanation. Explanations are found in the answer section in this chapter.

1. (example) Worry and stress turn hair gray. The graying of hair is a genetic phenomenon. Melanocytes, the cells that produce the pigments in the hair, stop producing pigments at different times in different people as a result of genetics, not stress.
2. If you cross your eyes they may get stuck.
3. Your heart stops when you sneeze.
4. Heartburn is in your heart.
5. Chemicals are bad for you.
6. Plants respire only at night.
7. Daughters inherit their physical characteristics from their mothers and sons from their fathers.
8. All deciduous trees are angiosperms.
9. The most abundant phenotype in a population represents the dominant trait.
10. All plant shoots are phototropic (grow towards light).
11. When lemmings are overpopulated, they commit suicide by running off cliffs into the ocean
12. Anaerobic respiration only takes place when there is no air.
13. The heart is on the left side of the body.
14. All plants are photosynthetic
15. The stomach occupies most of your abdomen.
16. Food enters the blood stream from the stomach.
17. Alcohol is a stimulant.
18. The cornea is simply a window to the eye, and the lens alone focuses light.
19. Arteries carry oxygenated blood, and veins carry deoxygenated blood.
20. Muscles contract and expand to cause motion.
21. Misnomers. A misnomer is a misleading name. Explain why the following are misnomers.
  1. juvenile diabetes - Both children and adults may have either Type 1 (“juvenile”) or Type 2 diabetes.
  2. adult stem cells
  3. peanuts
  4. coconut
  5. poison oak
  6. seagrass
  7. pinenuts
  8. abscissic acid
  9. dark reactions
  10. century plant
  11. koala bear
  12. starfish