Biology · PYQ NEET UG 2020

In relation to Gross primary productivity and Net primary productivity of an ecosystem, which one of the following statements is correct?

1. Gross primary productivity is always more than net primary productivity.
2. Gross primary productivity and Net primary productivity are one and same.
3. There is no relationship between Gross primary productivity and Net primary productivity.
4. Gross primary productivity is always less than Net primary productivity.