What is the term for the upper layer of a forest, formed by the crowns of trees?

In a forest ecosystem, which term describes the layer of vegetation that grows in the shade of the canopy above?

What is the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms?

Which biome is characterized by cold climates, evergreen forests, and is found just below the Arctic Circle?

What term describes the permanently frozen layer of soil found in the polar regions?

Which zone of a water body is well-lit and supports a high density of photosynthetic organisms?

In which zone of a water body does sunlight not penetrate, making photosynthesis impossible?

What term is used to describe small and often microscopic organisms that drift or float in the sea or freshwater, including both phytoplankton and zooplankton?

Which term refers to land areas that are saturated with water, either permanently or seasonally, and include marshes, swamps, and bogs?

What is the term for the tidal mouth of a large river, where the tide meets the stream?