Calculation of biological energy flow

Do you get dizzy every time you see the calculation problem of energy flow? Don't be afraid, let's break through together.

First, reunion knowledge points

Note: W 1 solar energy fixed by plants; A: energy lost by breathing; B: unused energy; C: energy flowing into the decomposer; D: Energy flowing into the next trophic level.

Energy flowing into the ecosystem.

= solar energy fixed by plants (w1);

2. Transfer efficiency = assimilation amount of this trophic level (D 1)/ assimilation amount of the previous trophic level (w1) ×100%; The transmission efficiency is between 10%-20%;

3. Energy consumed by consumers = energy absorbed by consumers+energy in feces;

4. Energy absorbed by one trophic level = energy consumed by respiration+energy absorbed by the next trophic level+energy utilized by decomposers+energy not utilized; (w 1 = a 1+d 1+c 1+b 1)

5. Consumer assimilation energy = respiratory consumption+growth and reproduction;

6. Growth, development and reproduction = decomposition and utilization of decomposers+assimilation of the next trophic level+unused.

Second, meet the real problem

1. The following table is the measurement result of energy flow in an ecosystem (unit is J/hm2 a), in which the food chain is only "plants → voles → weasels".

Answer according to the table:

(1) The total energy flowing through this ecosystem is _ _ _ _ _ _ _ _ j/hm2 a.

(2) The ability transfer efficiency of voles to weasels is _ _ _ _ _ _.

(3) Among the energy obtained by MICROTUS voles, the energy used for life activities such as growth, development and reproduction is _ _ _ _ _ _ j/hm2·a, and the rest energy is mainly lost in the form of _ _ _ _ _ _.

Answer (1) 2.45×1011

(2)3%

(3)3.5× 107; heat energy

The analysis (1) shows that the total energy flowing through the ecosystem is the total solar energy fixed by the producer.

(2) The energy transfer efficiency from vole to ferret is 2.25×107 ÷ 7.50×108×100% = 3%.

(3) assimilation amount of growth, development and reproduction = 7.50×108-7.15×108 = 3.5×107j/hm2 a; Most of it is lost in the form of heat energy during breathing.

2. The picture on the right is the result obtained by American ecologist Lin Deman when he measured the energy flow of a natural lake-Lake Seidberg in 1942. According to the relevant data in the figure, the energy transfer efficiency from the second trophic level to the third trophic level is _ _.

The answer is 20%

In this system, the third trophic level is carnivorous animals, assimilation amount is 12.6, the second trophic level is herbivorous animals, and assimilation amount is 62.8. The energy transfer efficiency from the second trophic level to the third trophic level is12.6/62.8×100% = 20%.

The above is a detailed explanation of energy flow calculation that you need to know in the biology teacher recruitment exam. Have you learned? It is easy to understand the essence.