Read the following information carefully and answer the given questions.…
2021
Read the following information carefully and answer the given questions.
Bioluminescence, emission of light by an organism or by a laboratory biochemical system derived from an organism. It could be the ghostly glow of bacteria on decaying meat or fish, the shimmering radiance of protozoans in tropical seas, or the flickering signals of fireflies. The phenomenon occurs sporadically in a wide range of protists and animals, from bacteria and fungi to insects, marine invertebrates, and fish, but it is not known to exist naturally in true plants or in amphibians, reptiles, birds, or mammals. Bioluminescence results from a chemical reaction (chemiluminescence) in which the conversion of chemical energy to radiant energy is direct and virtually 100 percent efficient; i.e., very little heat is given off in the process. For that reason, the emission is called cold light or luminescence. The functional role of bioluminescence in lower organisms such as bacteria, dinoflagellates, and fungi is difficult to discern. Partly because the glow of luminous bacteria is extinguished when oxygen is removed, it has been suggested that the bioluminescent reaction was originally used to remove oxygen toxic to primitive types of bacteria that developed when oxygen was absent or very rare in Earth’s atmosphere. The metabolic reaction that combines the oxygen with a reducing substance (luciferin) liberates sufficient energy to excite a molecule in the organism to emit visible radiation. Most of those luminous primitive organisms subsequently developed systems of using oxygen, but they have retained the luminescent capability as parts of related metabolic pathways or for some survival value that luminescence may confer on the organism.
What can be the suitable title for the passage?
- A.
What is Bioluminescence?
- B.
Organisms and their light
- C.
Role of bioluminescence
- D.
Why Bioluminescence?
Attempted by 3 students.
Show answer & explanation
Correct answer: A
Best title: What is Bioluminescence?
Explanation: The passage defines bioluminescence, gives vivid examples of where it appears (bacteria, protozoans, fireflies, marine animals), describes the chemical mechanism that produces light, and briefly mentions possible evolutionary context. The overall aim is to explain the phenomenon itself, so a definitional title is most appropriate.
Defines the term and nature of the phenomenon (what bioluminescence is).
Provides examples of organisms that exhibit bioluminescence.
Explains the chemical mechanism (luciferin, oxygen, cold light) and energy efficiency.
Mentions possible historical/evolutionary role only as a secondary point.
Why the other titles are less suitable:
"Organisms and their light": Too broad and organism-focused; the passage is centered on the phenomenon and its mechanism rather than cataloguing organisms.
"Role of bioluminescence": Emphasizes function; the passage only briefly speculates about possible roles and mainly explains what bioluminescence is.
"Why Bioluminescence?": Implies a focus on causes or evolutionary reasons; the passage is more descriptive and mechanistic than causal.
Conclusion: "What is Bioluminescence?" best matches the passage's definitional and explanatory content.