A mass extinction
a. Is global in scale
b. Affects many different groups of organisms
c. Is caused only by human activity
d. A and B are correct
e. A, B, and C are correct

Verified step by step guidance

1. Step 1: Begin by understanding the term 'mass extinction.' A mass extinction refers to a significant and widespread loss of species across the globe within a relatively short geological time frame.
2. Step 2: Analyze option (a): 'is global in scale.' This is correct because mass extinctions impact ecosystems worldwide, not just localized areas.
3. Step 3: Analyze option (b): 'affects many different groups of organisms.' This is also correct because mass extinctions typically result in the loss of biodiversity across various taxa, including plants, animals, and microorganisms.
4. Step 4: Analyze option (c): 'is caused only by human activity.' This is incorrect because mass extinctions have occurred throughout Earth's history due to natural causes such as volcanic eruptions, asteroid impacts, and climate changes. Human activity is a factor in the current biodiversity crisis but not the sole cause of all mass extinctions.
5. Step 5: Combine the correct options (a and b) and evaluate the answer choices. The correct answer is (d): 'A and B are correct.'

Key Concepts

Mass Extinction Events

Mass extinction events are significant and rapid decreases in biodiversity on Earth, characterized by the loss of a large number of species across various taxa. These events are typically global in scale and can drastically alter ecosystems and the evolutionary trajectory of life. Historical examples include the Permian-Triassic extinction and the Cretaceous-Paleogene extinction.

Causes of Mass Extinction

Mass extinctions can be triggered by a variety of factors, including natural phenomena such as volcanic eruptions, asteroid impacts, and climate change. While human activity has accelerated extinction rates in recent times, it is not the sole cause of historical mass extinctions. Understanding these causes helps in assessing the current biodiversity crisis.

Biodiversity and Ecosystem Impact

Biodiversity refers to the variety of life in a particular habitat or ecosystem, encompassing species diversity, genetic diversity, and ecosystem diversity. Mass extinctions significantly impact biodiversity, leading to the collapse of ecosystems and loss of ecological functions. The interdependence of species means that the loss of one can have cascading effects on others.