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For IGCSE O-Level Biology students Chapter 16
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Ecology
The study of living organisms; how they affect each other
and their surroundings.
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.
AdaptationA body part, body covering, or behavior that helps an animal survive in its
environment.
• BehaviorThe actions of an animal.
• CamouflageA colour or shape in an animal's body covering that helps it blend into its environment.
• EnvironmentEverything that surrounds and affects a living thing. The environment includes non-living things, such as water and air, as well as other living things.
• MimicryAn adaptation in which an otherwise harmless animal looks like a harmful animal in order to protect itself.
An example of mimicry: a butterfly with wings that look like an owl’s face
• An example of mimicry: a Viceroy butterfly looks like the poisonous
Monarch butterfly to fool its predators.
An example of camouflage: a stick insect camouflaged to hide easily between tree branches
• 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
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.
Type of nutrition
Hetrotrophic
parasitic saprotrophic Holozoic
Herbivore Carnivore
Omnivore
What would you call these?
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.
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.
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.
Counting/sampling organisms
QuadratA 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.
Pitfall trapA 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.
Tullgren funnelA 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.
Inverted pyramid of numbers
Pyramid of biomass
Energy pyramid
Factors affecting size of population
1. Availability of food2. Presence of predators3. Spread of disease
Factors affecting human population
1. Medical care advances2. Sanitation 3. Large food production4. Use of machinery in agriculture5. Increased education6. Increased family planning methods
Water cycle
Carbon cycle
Nitrogen cycle10
