Integrated ScienceStudents session


Welcome to ecology lesson two. Here are the answers for lesson one, honestly mark yourself and do the necessary corrections.

view previous lessons 

1. Biotic factor is living organisms in an environment or the living components of a habitat/ environment and how ways they interact with each other.

2. Examples of useful biotic factors
i. Bacterial fixing nitrogen in the soil.
ii. Birds acting as agents of pollination.
iii.Fungi and bacteria decomposing organic matter.

Population; refers to a group of organisms of the same species occupying a particular habitat. E.g., a tree could house a population of birds.

It is a population of different species living in a particular habitat or interacting with each other.
For example, the ocean could be a community for different species of fish, crabs, coral,

Is part of the earth or atmosphere that supports life.

Answers to practical lessons

a) A. Rain gauge

B. Pooter

C. Sweep net


I. Measuring cylinder

II. Funnel
III. Flexible tube
IV. Filter or Cloth
V. Wooden Handle
VI. Net

Functions of A, B and C


c) A. is use to measure amount of rainfall
B. is use to collect small animals
C. is use to trap some vertebrates either in water or on land.

d) Functions of parts

II. is used for collecting and measuring rain
III. to suck small animals or insects.
IV. For trapping some vertebrates either on land or in water eg frog, insects, fish

e) How A is used to measure abiotic factors

A metal cylinder is put in the ground in an open field for rain to fall into it directly.
Rainfall is directed into the measuring cylinder by the help of the funnel
Rain amount is measured within a specified interval and recorded
A graph is plotted with the results to understand the dynamics or the rain fall pattern.


Types of ecosystems and their components
Food chain and food web

Ecosystem can be classified into 2

1. Natural ecosystem
2. Artificial Ecosystem

Natural Ecosystem includes

Tropical rainforest, Tropical savannah, lakes, Marine, estuaries etc

Artificial Ecosystem includes

Farmlands, lakes, roads…

There are Terrestrial ecosystem and aquatic ecosystem as the main natural types of ecosystem

Terrestrial ecosystem (land) can be divided into
Tropical rainforest
Tropical savannah
Tropical desert
Mangrove swamps

Aquatic Ecosystem ( water )

The water covers about 70% of the earth surface.
There aquatic ecosystem has
Fresh water ecosystem and Marine or salt water ecosystem

What about estuaries?

They are between fresh water and marine mainly classified as marine.
It is just ecosystem where the seawater meets the fresh water.

One feature of organisms within a given habitat is their inter-dependence in their feeding habit.

Food chain:

Components of ecosystem


These are the green plants that manufacture their own food through photosynthesis Examples are tomato, yam, maize, mango, etc.


These are the animals that consumes, they are not able to make their own food. We have primary, secondary, and Tertiary consumers.

Primary consumers These are organisms which feed on the producers. They are mostly herbivores. Examples include butterfly, grasshoppers, goat, deer etc.

Secondary consumer: These organisms feed on and obtain energy from primary consumers.
They are mostly carnivores. Examples include snake, cat, shrew, etc

Tertiary consumers: These consumers feed on secondary consumers, and hence, obtain energy from them. They are either carnivores or omnivores. Examples include man, owl, lion, etc.

These are the organisms that act on dead plants and animal remains.

The sun
The ultimate source of energy.

Trophic Levels

This is the steps by step pathway along which energy is transferred.
Producers These are organisms which produce their own food through photosynthesis. Only green plants do that.

Food chain

A food chain is a string of organisms within an ecosystem which are connected through their mode of feeding or a linear sequence of feeding where organisms feeding are also being fed on.
Grass – to – Grasshopper – to- toad – to – snake

Food web.

A food web is a number of food chains linked together.

Further explanation and examples will be given during face to face lesson with your Teacher.


1. The following are all abiotic factors except?
A. Wind
B. Light
C. Bacteria
D. Rainfall
Answer: C. Bacteria

2. All the following are are equipment for sampling organisms in terrestrial habitats except
A. Wicker-work trap
B. Sweep net
C. Butterfly net
D. Pooter
Answer A. Wicker-work trap

3. Which of the following is not associated with over crowding?
A. Housing
B. Employment
C. Food
D. labour
Answer D. labour

4. The mode of nutrition involving the use of dead organic matter is described as
A. Saprophytic
B. Symbiotic
C. Parasitic
D. Holophytic
Answer A. Saprophytic


5. In ecological study, small animals like ants found on leaves and crevices can be collected by
A. Sweep net
B. Pooter
C. Wicker-work trap
D. Transect
Answer D. transect

6. Which of the apparatus is used to investigate a sample of various plant species growing in a field?
Answer B. Quadrat
7. Which of the following members in a food chain will receive the least energy?
A. Grass
B. Hawk
C. Locust
D. Lizard
Answer: B. Hawk

8. Which of the following habitat is aquatic?
A. Farmland
B. Park
C. Pond
D. Rain forest
Answers C. Pond

9. Four- fifth of the volume of air in an environment is water vapour at a certain temperature. Calculate he relative humidity of the air.
A. 80%
B. 70%
C. 60%
D. 50%
Answer A. 70%


10. A food web is a
A. Relationship between non-living components of the ecosystem
B. Relationship between the living and non- living organisms in an ecosystem
C. Complex feeding relationship between living organisms in ecosystem
D. Relationship between the living organisms in an ecosystem
Answer: C. Complex feeding relationship between living organisms in ecosystem




  1. State four ecological factors that affects crop production
  2. Explain the term human population
  3. State three factors that affects the distribution of human population
  4. What is conservation of natural resources
  5. List three benefits of forest conservation.
  6. What is population density?
  7. State three effects of high population density on the environment.
  8. List three ways in which plants and animals are interdependent
  9. list three benefits of forest
  10. Draw a simple food web of an ecosystem.

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