Question

Assume that an insect eats plant seeds containing 100 J of energy. A part of this energy is lost or is unassimilated in the form of faeces; while the rest is assimilated through respiration and biomass production. It uses 36 J of that energy for respiration and excretes 52 J in its faeces. 

(i) How much is the insect's net secondary production ?

(a) 12 J

(b) 48 J

(c) 24 J

(d) 36 J

(ii) Production efficiency is the percentage of energy stored in assimilated food that is not used for respiration. In the case of the insect described above, what will be its production efficiency ? 

(a) 5.8 %

(b) 25 %

(c)75%

(d) 92 %

Answer 1

(i) Insects net secondary production is (a) 12 J.

Net secondary productivity(NSP) = Gross secondary productivity(GSP) – Respiratory loss(R).

= 100 – (52 + 36) = 12 J