For IGCSE O-Level Biology students Chapter 16

1. Ecology
The study of living organisms; how
they affect each other and their
surroundings.

2. Terms to learn before we start.
• Habitat: is the place
where an organism
lives.
• Environment :is the
surroundings of an
organism.
• Adaptation: a feature
that helps the organism
to survive in its
environment.

3. Adaptation
A body part, body covering, or behavior that
helps an animal survive in its environment.
• Behavior
The actions of an animal.
• Camouflage
A colour or shape in an animal's body covering that helps it
blend into its environment.
• Environment
Everything that surrounds and affects a living thing. The
environment includes non-living things, such as water and
air, as well as other living things.
• Mimicry
An adaptation in which an otherwise harmless animal looks
like a harmful animal in order to protect itself.

4. An example of mimicry: a butterfly with wings that
look like an owl’s face

5. • An example of mimicry: a Viceroy
butterfly looks like the poisonous
Monarch butterfly to fool its predators.

6. An example of camouflage: a stick insect
camouflaged to hide easily between tree branches

7. • Predator: an animal
that hunts and eats
other animals.
• Prey: an animal that is
eaten by a predator
• Herbivore: an organism
that feeds on plants.
• Carnivore: an organism
that feeds on animals.
• Omnivore :an organism
that feeds on both
plants and animals

8. Energy flow, food chains & food webs
• The main source of
energy for all living things
is the ……………
• This energy is captured by
…………………..
• Producer: an organism
that can make its own
food
• Consumer: an organism
that feeds on other
organisms.

9. Type of nutrition
Hetrotrophic
parasitic saprotrophic Holozoic
Herbivore Carnivore
Omnivore

10. What would you call these?

11. Energy flow & food chains
• Energy from the sun flows in one direction .
• Food chain: shows the feeding relationships of
organisms with arrows representing the energy
flow.

12. Food web: is a group of interconnected
food chains.
• Can you name:
• 2 producers?
• 2 primary consumers?
• 2 secondary consumers?
• A tertiary consumer?
• Write down a food chain
that contains four
organisms.

13. More terms!!!
• Population: the number of organisms of the
same species in one area.
• Community: all the different populations
present in one area.
• Ecosystem: a system containing all non-living
and living things in the same area.

16. Counting/sampling organisms

17. Quadrat
A Quadrat is used to
count plants or
marine organisms
that are fixed to
their spot.
It is placed randomly
and organisms are
counted then
repeated in another
spot. An average
number is calculated
at the end.

18. Pitfall trap
A pitfall trap is a container
that is sunk into the ground
so that its rim is level with the
soil surface. Insects and other
arthropods are captured
when they fall into the trap.
To prevent arthropods from
escaping or preying on each
other, pitfall traps usually
contain a killing/preserving
agent such as pet safe anti-
freeze, soapy water, or ethyl
alcohol.
The trap is covered with a
raised lid to keep out rain and
predators.

19. Tullgren
funnel
A method that could be
used to collect small
organisms living
amongst fallen leaves or
in the soil.
The heat and light from
the lamp drives the
organisms into the
beaker, the alcohol
preserves them.

20. Inverted pyramid of numbers

21. Pyramid of biomass

22. Energy pyramid

23. Population curve

24. Human population curve

25. Factors affecting size of population
1. Availability of food
2. Presence of predators
3. Spread of disease

26. Population pyramids

28. Factors affecting human population
1. Medical care advances
2. Sanitation
3. Large food production
4. Use of machinery in agriculture
5. Increased education
6. Increased family planning methods

30. Carbon cycle

31. Nitrogen cycle
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