Tuesday
May 21, 2013

# Homework Help: biology help?

Posted by sam on Saturday, February 9, 2013 at 8:05am.

This question addresses the 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.
(1) 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
(2) 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 and
energy lost as waste products. Give your final answer to two significant
figures.
energy lost to respiration = energy assimilated - increase in biomass
i need someone to help me to do this calculation step by step .thanks

• biology help? - Devron, Sunday, February 10, 2013 at 3:21am

1.________________________________________________
[(total energy-NPP)/total energy]*100= % energy lost

(1.2 × 106 kJ m−2 y−1)-(5.0 × 103 kJ m−2 y−1)/1.2 × 106 kJ m−2 y−1}*100= % energy lost

Which is about 99%, but if I round up, I get 100% because my calculator tells me 99.6%. So unless your teacher allows you to report it as just 99%, I do not know what to tell you unless I have done this calculation wrong.

2._______________________
(7.1 × 102 kJ m−2 y−1)-(4.9 × 102 kJ m−2 y−1)=2.2 x10^2 kj m-2 y-1

I hope this helps or I at least hope someone else gives you some input.

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