9. What is primary productivity? Give brief description of factors that affect primary productivity.
5 . What is the percentage of photosynthetically active radiation (PAR) in the incident solar radiation?
(b) 50 %
2. Which one of the following has the largest population in a food chain?
(b) Primary consumers
(c) Secondary consumers
1. Fill in the blanks.
(c) In aquatic ecosystems, the limiting factor for the productivity is_________.