Question Video: Identifying a Potential Mass Extinction Event Science

Extinctions can occur on a large scale with many different species, which is known as a mass extinction. Which of the following is a potential cause of a mass extinction event? [A] An increase in available sunlight. [B] A decrease in human activities, such as traveling between countries. [C] Toxic or harmful gases released from a large volcanic eruption. [D] A disease specific to one species being passed through a population.

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Video Transcript

Extinctions can occur on a large scale with many different species, which is known as a mass extinction. Which of the following is a potential cause of a mass extinction event? (A) An increase in available sunlight. (B) A decrease in human activities, such as traveling between countries. (C) Toxic or harmful gases released from a large volcanic eruption. Or (D) a disease specific to one species being passed through a population.

A mass extinction refers to the termination of a large number of species in a relatively short period of time. So, we are talking about a situation that widely affects all life on Earth and quickly reduces the number of species all over the world. Common reasons for mass extinctions include natural disasters, changes in climate, and man-made causes. These all can change an environment, cause death themselves, and/or make it more difficult for organisms to find food or reproduce. As a result of any of these, there may be few-to-no offspring produced by a particular species. Eventually, if no offspring are produced, once the existing individuals have died, the species will become extinct. If this is happening for many species at once due to drastic changes in the world that make survival or reproduction difficult, we have a mass extinction event.

Let’s look through the answers to see which describes a situation likely to result in a mass extinction event. An increase in sunlight, as described in answer option (A), would likely increase photosynthesis and therefore allow more plant growth. These plants will be available food for other species. So, this situation would support more life and would be unlikely to result in many species becoming extinct at the same time. So, we can eliminate (A).

A decrease in human activities, as described in answer option (B), would be likely to reduce environmental change. This would allow most species to continue to live as they always have. Less travel between countries would likely result in lower carbon emissions, which would reduce the climate change induced by such emissions. Again, this would result in less change to the environment. A stable environment is not likely to cause a mass extinction, quite the opposite. So, we can eliminate (B).

Toxic or harmful gases released from a large volcanic eruption, as described in answer option (C), describes a natural disaster with toxic or poisonous effects. This sounds like something that could cause the death of organisms in the environment where it occurred. Since it is a large eruption, this could potentially cause enough death to result in many species becoming extinct at once. So, this looks like it could be our answer, but let’s check the last choice to be sure.

A disease, like the one described in answer option (D), can cause an extinction. However, a mass extinction refers to the extinction of many species at once. Since the disease described would only potentially result in the extinction of a single species, it would not produce a mass extinction. So, we can eliminate (D).

Therefore, the only listed situation likely to be the cause of a mass extinction event is (C): toxic or harmful gases released from a large volcanic eruption.

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