What is incorrect regarding the overgrowth of algae due to farm run-off?

The correct answer highlights that the statement regarding algae being heterotrophs is incorrect. Algae are primarily autotrophs, meaning they can produce their own food through photosynthesis by utilizing sunlight, water, and carbon dioxide. This ability allows them to thrive in nutrient-rich environments, such as those created by farm run-off, which often contains fertilizers that enhance algal growth.

When discussing the harmful overgrowth of algae, it’s essential to understand that while they do need sunlight for photosynthesis and can indeed deplete oxygen levels in the water, their role as autotrophs distinguishes them from heterotrophs, which cannot produce their own food and must rely on organic substances from their environment. In aquatic systems, excessive algal blooms can lead to oxygen depletion, especially when the algae die and decompose, leading to hypoxic conditions detrimental to fish and other aquatic life.

Consequently, while the other statements about algae being autotrophic, requiring sunlight, and their potential to deplete oxygen are accurate, the assertion that they are heterotrophs is fundamentally flawed, as it misrepresents the basic nutritional mode of algae.