Question : Comprehension:
An endangered species is a type of organism that is threatened by extinction. Species become endangered for two main reasons: loss of habitat and loss of genetic variation. A loss of habitat can happen naturally. Dinosaurs, for instance, lost their habitat about 65 million years ago. The hot, dry climate of the Cretaceous period changed very quickly, most likely because of an asteroid striking the Earth. The impact of the asteroid forced debris into the atmosphere, reducing the amount of heat and light that reached Earth's surface. The dinosaurs were unable to adapt to this new, cooler habitat. Dinosaurs became endangered, then extinct. Human activity can also contribute to a loss of habitat. Development for housing, industry, and agriculture reduces the habitat of native organisms. This can happen in several different ways.
Development can directly eliminate habitat and native species. In the Amazon rainforest of South America, developers have cleared hundreds of thousands of acres. To "clear" a piece of land is to remove all trees and vegetation from it. The Amazon rainforest is cleared for cattle ranches, logging, and urban use. Development can also endanger species indirectly. Some species, such as fig trees in the rainforest, may provide habitat for other species. As trees are destroyed, species that depend on that tree habitat may also become endangered. Tree crowns provide habitat in the canopy, or top layer, of a rainforest. Plants such as vines, fungi such as mushrooms, and insects such as butterflies live in the rainforest canopy. So do hundreds of species of tropical birds and mammals, such as monkeys. As trees are cut down, this habitat is lost. Species have less room to live and reproduce.
Based on the passage above, choose the correct option for the following question.
Question
According to the passage, which of the following are the two main reasons for species becoming endangered species?
Option 1: Loss of sunlight and Loss of water
Option 2: Loss of roads and loss of hunting grounds
Option 3: Loss of habitat and Loss of genetic variation
Option 4: Acid rain and floods
Correct Answer: Loss of habitat and Loss of genetic variation
Solution : The right choice is the third option (refer to the first paragraph) .
The passage explains that species become endangered primarily due to two factors:
- Loss of Habitat: This refers to the reduction or destruction of the natural environment where a species lives. For example, the passage mentions how the dinosaurs lost their habitat due to climate change following an asteroid impact.
- Loss of Genetic Variation : Genetic diversity is crucial for a species to adapt to changing environments and to resist diseases. When there's a reduction in genetic variation, a species becomes more vulnerable to environmental changes.
Therefore, the two main reasons for species becoming endangered are loss of habitat and loss of genetic variation.
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