This document contains a worksheet with questions about energy flow through food chains and farming systems. Figure 1 shows a food chain with primary producers, cattle, and humans. Students are asked to (1) calculate the percentage of energy lost from primary producers to humans, and (2) explain why crop farming is more energy efficient than sea harvesting. They are also asked to (3) suggest two ways energy can be lost from the system. Additionally, students are asked to (1) list three reasons why livestock are part of most farming systems, and (2) annotate a systems diagram of a farm to identify two inputs and outputs and their potential environmental impacts.

1. Guru charan kumar
IB ESS
2013
SYSTEMS & MODEL WORKSHEET 2
Figure 1 shows energy flow through a food chain.
Figure 1
primary producers
–
900 kcal m 2 yr–1
(a)
(i)
cattle
256 kcal m–2 yr–1
human
6.6 kcal m–2 yr–1
Calculate the percentage energy loss to humans from the initial input of
900 kcal m–2 yr–1.
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(2)
(ii)
Explain why farming systems based on crop production are more energy
efficient than harvesting from the sea.
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(2)
(iii)
Suggest two ways in which energy may be lost from the system.
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(2)
(b)
(i)
Suggest three reasons why livestock (cattle, goats, sheep, etc.) form a part of
most farming systems.
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2. Guru charan kumar
IB ESS
2013
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(3)
(ii)
Figure 2 shows a systems diagram for a farm. Annotate the diagram to show
two inputs and two outputs, and their possible environmental impacts.
Figure 2
INPUTS
Input
Impact
Input
Impact
OUTPUTS
Output
Impact
Output
Impact
(4)
(Total 13 marks)