AP BIOLOGY

Detailed explanation-1: -Plants typically capture and convert about 1.3% to 1.6% of the solar energy that reaches Earth’s surface and use about a quarter of the captured energy for metabolism and maintenance. So, around 1% of the solar energy reaching Earth’s surface-per unit area and time-ends up as net primary productivity.

Detailed explanation-2: -The primary producers convert only 1% of the energy in the sunlight available to them into NPP. Out of this, only 10% is available for the organisms at the next trophic level.

Detailed explanation-3: -Between 98 and 99 percent of solar energy reaching Earth is reflected from leaves and other surfaces and absorbed by other molecules, which convert it to heat. Thus, only 1 to 2 percent is available to be captured by plants.

Detailed explanation-4: -On average, plant gross primary production on earth is about 5.83 x 106 cal m-2 yr-1. This is about 0.06% of the amount of solar energy falling per square meter on the outer edge of the earth’s atmosphere per year (defined as the solar constant and equal to 1.05 x 1010 cal m-2 yr-1).

Detailed explanation-5: -But photosynthesis is a relatively inefficient process, usually capturing only about 5 percent of available energy, depending on how efficiency is measured.