The open ocean and tropical rain forests contribute the most to Earth's net primary production because a. both have high rates of net primary production. b. both cover huge surface areas of Earth. c. nutrients cycle fastest in these two ecosystems. d. the ocean covers a huge surface area and the tropical rain forest has a high rate of production.

Verified step by step guidance

1. Understand the concept of net primary production (NPP), which is the rate at which all the plants in an ecosystem produce net useful chemical energy.
2. Consider the factors that contribute to high NPP, such as availability of sunlight, water, and nutrients, as well as the area covered by the ecosystem.
3. Evaluate the characteristics of the open ocean and tropical rain forests in terms of these factors.
4. Analyze the options given: (a) focuses on rates of NPP, (b) considers the surface area, (c) discusses nutrient cycling, and (d) combines the ideas of surface area and rate of production.
5. Determine which option best explains why these two ecosystems contribute the most to Earth's NPP by linking the characteristics of these ecosystems to the factors that enhance NPP.

Key Concepts

Net Primary Production (NPP)

Net Primary Production (NPP) refers to the amount of organic matter produced by photosynthetic organisms, minus the organic matter consumed by respiration. It is a crucial measure of ecosystem productivity, indicating how much energy is available to support the food web. High NPP is typically found in ecosystems with abundant sunlight and nutrients, such as tropical rainforests and open oceans.

Ecosystem Surface Area

The surface area of an ecosystem plays a significant role in its overall productivity. Larger ecosystems, like the open ocean, can support vast populations of photosynthetic organisms, leading to higher total production. In contrast, smaller ecosystems may have limited production potential, regardless of their NPP rates. Thus, both the size and productivity of an ecosystem are important for understanding its contribution to global NPP.

Nutrient Cycling

Nutrient cycling refers to the movement and exchange of organic and inorganic matter back into the production of living matter. In ecosystems like tropical rainforests and the open ocean, efficient nutrient cycling supports high rates of primary production. However, while nutrient cycling is important, it is not the sole factor determining NPP; the combination of surface area and production rates is also critical.