1. Figure 1 below shows an aquatic and terrestrial food web.
water bird
hawk
ocelot
water snail
tadpole
fish
squirrel
mosquito larvae
pond weed
flycatcher
caterpillar
iguana
microscopic animals
grasshopper
plant materials, leaves fruits aeeds
microscopic plants
Aquatic food web
Terrestrial food web
Figure 1: Diagram of two food webs
a. Table 1 below contains examples of organisms at different trophic levels. Complete table 1 using only
organisms shown in the food web in figure 1.
Table 1: organisms at different trophic levels in figure 1
Trophic levels
Aquatic food web
Pond weed
Terrestrial food web
Plant materials, leaves, fruit ,
seeds
Primary consumer
Fish
Fly catcher
Tertiary consumer
(3 marks)
b. Identify TWO similarities between aquatic and terrestrial food webs
________________________________________________________________________________________
________________________________________________________________________________________
_______________________________
(2 marks)
c. State 2 consequences giving reasons if the iguana was removed from the food web.
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________
(4 marks)
d. In the space provided below, construct a labelled pyramid of biomass to present the data collected for
constructing the terrestrial food web shown in figure 1.
(3 marks)
e. Construct a food chain with at least FOUR organisms from each food web in figure 1.
________________________________________________________________________________________
__________________________________________________________________________
( 4 marks)
f. Producers and decomposers can be described as being the most essential organisms in nature. State if you
agree with the above statement, and give reasons with your answer.
________________________________________________________________________________________
________________________________________________________________________________________
________________________________________________________________________________________
( 3 marks)
2. Figure 2 below represents the energy flow through a food chain consisting of four organisms. The total energy
in the green plants is shown in the box.
Figure 2
a. Complete the other boxes to show the total energy in the tissues of the consumers, assuming a 90% loss
of energy at each of the stages in the food chain.
( 1 ½ marks)
b. State two processes which result in the loss of energy that occur between the stages.
__________________________________________________________________( 1 marks)
c. State the term used to describe the tertiary consumer that feeds on both the secoundary consumer and
green plants. _____________________________________________ ( ½ marks)
d. State with a reason another term used to describe primary consumers in a food chain or food web
_____________________________________________________________________________________
____________________________________________________________( 1
½
marks)
e. Explain, giving two reasons, why there are rarely more than four to five links (or stages in a food
chain)________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_______________________________________________( 2 marks)
f.
Discuss why food webs are necessary in nature.
_____________________________________________________________________________________
_____________________________________________________________________________________
______________________________________________________( 3 marks)
3. a.
It was observed that an Acadia plant secreted a sap that was fed upon by ants. When a caterpillar
attempted to consume the leaves of the Acadia plant it was attacked by the ants. The same species of
caterpillars had no problems while feeding on the leaves of plants right next to the Acadia. It was noted that
many ant trails were seen running across these plants towards the Acadia plant however these plants did not
look healthy as they were fed upon by many caterpillars.
Study the passage above and answer the following questions
i. Define the term symbiosis. ____________________________________________________
____________________________________________________ ( 1 mark)
ii. List the types of symbiotic relations outlined in the passage,
____________________________________________________ ( 1 ½ marks)
iii. Describe the symbiotic relationships that occur:
between the ant and Acadia plant
______________________________________________________________________________
______________________________________________________________________________
____________________________________________________________
between the caterpillar and the plants surrounding the Acadia
______________________________________________________________________________
______________________________________________________________________________
___________________________________________________( 5 marks)