Past Questions and Answers on Ecology



1.      Which of the following best describes the biosphere?
A. The non-living parts of an environment
B. all ecosystems and the organisms which inhabit them
C. All living parts of an ecosystem
D. All the members of a single species in a habitat

2.      The earthworm can be classified as
A.    decomposer       
B.     producer  
C. primary consumer      
D. secondary consumer

3.   Mutualism is exhibited by
A.    tapeworm living in the gut of man
B.     yellow dodder growing on milk bush
C.     platycerium growing on palm tree
D.    rhizobium living in the root nodules of groundnut

4.      Food webs are complex because
A.    the number of producers is large
B.     many animals feed directly on them
C.     they include primary, secondary and tertiary consumers
D.    some animals form part of the several food chains

5. Which of the following group of organisms is made up of consumers?
A.    goat, dog, flea      
B.     grass, cassava, maize 
C.     maize, mouse, eagle
D.    cassava, lion, dog

6. The instrument used to determine pressure is
A.    anemometer      
B.     barometer       
C. hygrometer   
D. hydrometer

7. In fresh water habitat, the ecological factor which least affects organisms is
A.    oxygen content         
B.     temperature         
C. turbidity    
D. wind

8.      The ecological role of an organism in a habitat can be referred to as its
A.    biome             
B.     ecosystem   
C. micro-habitat   
D. niche

9.    the consumer in an ecosystem are usually
A.    carnivores           
B.     decomposers     
C. herbivores  
D. omnivores

10.   light intensity is measured with a/an
A.    barometer           
B.     thermometer        
C. photometer   
D. anemometer

11.  In an ecosystem, the LEAST efficient energy transfer link is from
A. producers to primary consumers
B. sun to producers 
C. primary consumers to secondary consumers
D. secondary consumers to decomposers

12.   Lichen is an example of
A. saprophytic organism
B. a symbiotic association
C. an epiphytic plant
D. a carnivorous plant

13.  The salinity of a brackish environment
A. increases immediately after rain
B. increase at the end of rainy season
C. Decrease with increase in micro-organisms
D. increase during dry season

14.  What do bacteria in root nodules derive from the host plant?
A. Protection and minerals
B. Water and minerals
C. Carbohydrates and water
D. Protection and carbohydrates

15.  The most important factors which influence an organism's way of life in its habitat are
A. the physicals and biotic environment
B. Food and water availability
C. temperature, water, light and predator-prey relationship
D. competition for food and spaces

16.  Organisms in an ecosystem are usually grouped according to their trophic level as
A. carnivores and epiphytes
B. consumers and parasites
C. producers and consumers
D. producers and saprophytes

17.  A food web is more stable than a food chain because
A. it contains more organisms
B. it has greater energy source
C. it is not easy to destroy
D. every organism has an alternative source

18.  Nitrogen-fixing microbes in leguminous plants live symbiotically in the
A. root nodules          
B. tap root         
C. branch roots         
D. root hairs

19.  The flowering period of plants in a habitat is determined by the
A. duration of sunlight
B. intensity and duration of rainfall
C. relative humidity of the atmosphere
D. temperature of the habitat

20.  A population is defined as a collection of similar organisms that
A. behaves in the same way
B. interbreed freely
C. are found in the same habitat
D. eat the same food

21.  In typical predator food chain involving secondary and tertiary consumers, the organism become progressively
A. smaller and more numerous along the food chain
B. equal in number and size along the food chain
C. larger and fewer along the food chain
D. parasitized along the food chain as consumers get bigger

Use the diagram below to answer question 22 & 23

22.  Which level of the pyramid has the least total stored energy?
A. E          
B. F           
C. G           
D. H

23.  Which organism in the pyramid functions as a tertiary consumer?
A. Algea                 
B. Shark             
C. Tadpole        
D. Tilapia

24.  What is the term used to describe the sum total of biotic and abiotic factors in the environment of the organism?
A. Habitat              
B. Biome           
C. Ecosystem        
D. Ecological niche

25.  Important abiotic factors which affects all plants and animals in the habitat are
A. temperature and turbidity
B. rainfall and relative humidity
C. salinity and wind direction
D. temperature and rainfall

26.  At which trophic level would the highest accumulation of a non-biodegradable substance occur?
A. Primary producers
B. Tertiary consumers
C. Primary consumers
D. Secondary consumers

27.  Two organisms of different species, living in close association but not dependent on each other are referred to as
A. parasites               
B. commensals         
C. symbionts    
D. autotrophs

28.  Which of the following instruments is NOT used in measuring abiotic factors in any habitat?
A. Microscopic             
B. Thermometer       
C. Hygrometer      
D. Wind vane

29.  The depth of illumination in a water body can be measured with a
A. photometer               
B. hydrometer           
C. secchi disc    
D. anemometer

30.  In a food chain involving a primary producer, a primary consumer as well as a secondary consumer, the sharing of trophic energy is in the form that the
A. the primary consumer has more energy than the primary producer
B. secondary consumer gets only a small portion of the energy contained in the primary producer
C. energy is shared equally between the three groups of organisms
D. secondary consumer takes up all the energy contents of the primary consumer


1. C

7. D     

13. D

19. A

25. C

2. A   

8. D  

14. A

20. B

26. B

3.  D  

9. A  

15. C

21. C

27. B

4. D  

10. C

16. C

22. D

28. A

5. A  

11. D

17. D

23. B

29. C

6. B  

12. B

18. A

24. C

30. B


1. (SSCE, 1994 &1996) (a) Explain the following ecological terms
(i) Population 
(ii) Habitat   
(iii) Food chain   
(iv) Ecosystem    
(v) Environment

(b). How do rainfall and its effect on abiotic factors influence biotic life in the biosphere?

(c). (i) Explain fully what happens in food chain.
(ii) What lesson(s) can be learnt from a food chain?

(a) & (b) Refer to the blog content 

(c) (i). In any food chain, transfer of energy from one organism to another occurs. Sunlight is the source of this energy and is converted to potential chemical energy in plants by photosynthesis, making green plants the producers.  Energy is decreased when transferred from the producer to the consumer. This is because some parts are not eaten, some undigested as feces and others use to respire.

(c) (ii). The shorter the food chain, the greater the amount of energy gained by the consumer.

2. (SSCE, 1997) (a) Define the following terms
(i) Mutualism                  
(ii) Parasitism
(ii) Commensalism

(a)   Explain the interdependence of plants and animal in a habitat

(a)  Refer to the blog content

(d) In a habitat, green plants are producers. They manufacture food and directly or indirectly are a source of food for animals. Carbon dioxide produced by animals is utilized by plants in photosynthesis. Animals released nitrogen waste that is utilized by plants. After the death of animals, they decay and release nutrients to plant.

3.      (SSCE, 1999 Q5). (a) What is meant by the following?
(i) Community               
(ii) Ecosystem
(iii) Food chain             
(iv) Food web

(b) (i) Explain briefly the term primary production. 
(ii) Most primary production goes to the decomposers rather than the primary consumers. Explain this statement.

(a)  Refer to the blog content

(b)(i) Primary production is the rate at which energy is bound in organic material created by photosynthesis per unit area of vegetation

(c) Most of the primary production goes into the development of tissues or normally eaten by consumers. Much of the primary production is lost through leaf fall. When the plant dies most of the incorporated primary production is lost to the primary consumer. Not all the parts of the plant that is eaten by the primary consumer is utilized. A greater proportion is indigestible and passed out as feces. Meanwhile dead plants and feces serve as the starting point for decomposer.

4.  (SSCE, 2001 Q3) Explain each of the following terms;
(i) food chain                    
(ii) food web
(iii) pyramid of biomass
(iv) decomposers
(v) pyramid of numbers

(b) Explain to what happens during energy flow in food chain. 

 Refer to the blog content

5.  (SSCE 2005 Q5) Define each of the following terms;
(i) Biomass                      
(ii) Producer
(iii) Primary consumer    
(iv) Food chain

(b) Describe the flow energy through a grazing food chain.

(c) How can the knowledge of flow of energy in a grazing food chain benefit a farmer? 


Refer to notes

(b) Energy transfer from plant to primary consumer is only 10% efficient. This is because some parts of plant are not eaten. Some of food eaten will not be digested, which will be eliminated as feces. Some are used for metabolic processes.
(c) Processed feed or digestible feed should be used for efficient used of food and the shorter the food chain, the more efficient is the use of the food provided.   

6.      (SSCE, 2007 Q3) (a)(i) State four ecological factors that common to all habitats and

(ii) List the instrument that could be used to measure the factors named in (a)(i) above.


Refer to the blog content

7.    (WASSCE 2013) 3(a)(i) Briefly describe three methods of determining food chains in a community.

(ii) State three ways in which the knowledge of food webs could be of importance to a fish farmer.


Direct observation: this is where the feeding habits of organism are observed in the community using naked eye or binocular. From such observation food chains and may be constructed.

Gut examination: this involves capturing, killing and dissecting animals to obtain samples of their gut contents.

Radioactive/trace methods: involves the use of labeled radioactive food substances in the field. All organisms which feed directly or indirectly on it are investigated using a radiation detector (Geiger counter).

1. Eliminate predators of the fish from the pond
2. Identify and introduce organisms eaten by the fish into the pond
3. Eliminate organism that compete with fish for food.

8. (WASSCE 2014) Explain briefly the following ecological term:

i) Biosphere;     

(ii) Habitat


 Refer to the blog content


  Click Here for WAEC Past Questions and Answers 

Post a Comment