Monday
December 9, 2013

# Homework Help: Biology PLEASE I NEED HELP!

Posted by Hayley on Saturday, June 15, 2013 at 9:35am.

Energy flow through a marine ecosystem?
The amount of solar energy falling on the surface of the sea in the English
Channel is 1.2 × 106 kJ m−2 y−1. Photosynthetic phytoplankton in the water
assimilate energy from sunlight to generate a gross primary production
(GPP) of 6.3 × 103 kJ m−2 y−1 and a net primary production (NPP) of
5.0 × 103 kJ m−2 y−1. Herbivorous zooplankton consume
4.0 × 103 kJ m−2 y−1 of phytoplankton biomass and the rest of the
phytoplankton die and sink to the bottom, so that 1.0 × 103 kJ m−2 y−1
passes to detritivores and decomposers, mainly bacteria. Zooplankton convert
7.1 × 102 kJ m−2 y−1 of the phytoplankton they consume to biomass, which
then passes to numerous predators that feed on the zooplankton. The waste
products of the zooplankton, 4.9 × 102 kJ m−2 y−1, sink to the bottom and
are consumed by detritivores and decomposers.
Note: kJ m−2 y−1 is a different (but equally valid)

(a) Calculate the percentage of the solar energy falling on the surface of the
water that is lost and does not pass into the food chain of this
ecosystem. Show how you worked through your calculation and give
(b) Calculate how much energy is lost from this ecosystem through
zooplankton respiration. Show how you worked through your calculation
making explicit use of the equations that describe the relationships
between respiration, biomass consumption, energy assimilation.

Equations:
energy assimilated = increase in biomass + energy lost in respiration

and

biomass consumption = energy assimilated + energy lost in faeces

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