Topic 5 Ib Biology Notes

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TOPIC 5
ECOLOGY
5.1.1
The study of the interactions between organisms and their environment. ENVIRONMENT = all the factors that affect an organism. 5.1.1 ABIOTIC FACTORS = non-living factors in an environment
BIOTIC FACTORS = living factors in an environment
ABIOTIC

BIOTIC

water

fish

chemicals in water

aquatic plant

depth

fungi

temperature

protists - algae

light
Relationship
- Photosynthesis
Wet lands = also called ‘estuary’
Ecosystem:
- A stable, settled unit of nature consisting of community of organisms, interacting with each other and with their surrounding physical and chemical environment. In order to be an
ecosystem, energy should
be transferred in a form of
organisms.
There should be a food
chain in order to be an
ecosystem, when one
organism eats the other.

SOME IMPORTANT ECOLOGICAL TERMS
5.1.1
Population: All living things of the same species in a habitat at any one time. Ex. Panda population in China in 1989
Community: All the living things in a habitat or ecosystem, the total of all populations. Species: A group of individuals of common ancestry that closely resemble each other and that are normally capable of interbreeding to produce fertile offspring. Biosphere: The inhabited part of the Earth. All ecosystems on Earth. NICHE = both the habitat of an organism occupies and the mode of nutrition employed G.1.5

HABITAT = place where an organism or population of organisms live. 5.1.4
FOOD CHAIN = used to show how matter & energy move through an ecosystem. It shows feeding relationship between organisms.
LIVING THINGS CAN BE CLASSIFIED ACCORDING TO THEIR ROLE IN AN ECOSYSTEM
5.1.3 and 5.1.14
• PRODUCERS: are the organisms which produce their own food by using inorganic molecules. Photosynthetic organisms or chemosynthetic.
• CONSUMERS: organisms which feed on other organisms.
a. Herbivores: they eat plants.
b. Carnivores: they eat meat.
c. Omnivores: they eat both meat and plants
• DECOMPOSERS: they feed on dead animals or plants, causing matter to be recycled by other living things.
Discuss the difficulties of classifying organisms into trophic levels. G.2.3 Sometimes it is hard to determine the trophic level of organisms on the secondary or tertiary consumers which feed on different organisms.

• What is the trophic level of omnivores?
• What is the trophic level of sea star in marine ecosystem

ECOLOGICAL PYRAMIDS
• Are graphical models of the quantitative differences that exist between the trophic levels of a single ecosystem.
• In accordance to the 2nd Law of Thermodynamics, there is a tendency for numbers and quantities to biomass and energy to decrease along food chains, therefore the pyramids become narrower toward the top.

PYRAMID OF BIOMASS represent the standing stock
(the dry weight) at each trophic level. G.1.8

• As you move up each trophic level, only 10% of the energy is transferred. • The other 90% is used for everyday life functions, metabolism. 5.1.9 • The main source of energy come from the sun
• Some of the energy are lost through heat

Construct a pyramid of energy, given appropriate information. G.2.5 Trophic level

Energy (kJm-2yr-1)

1
2
3
4

87 070
35 262
1 602
87

Trophic Level 4
Trophic Level 3

87 (kJm-2yr-1)
1 602 (kJm-2yr-1)
Trophic Level 2
(kJm-2yr-1)

Trophic Level 1

35 262

87 070 (kJm-2yr-1)

Bioaccumulation: If a chemical is not biodegradable, it accumulates in the body and causes disease, it is called bioaccumulation
Biomagnification: the process by which chemical substances become more concentrated at each trophic level. While the concentration of the chemical may not affect organisms lower in the food chain, it causes death in top trophic level because of high concentration.

The Cycling of Matter in Ecosystems 5.2.1
Chemicals in ecosystems are used again and again. In other words chemicals are recycled. This kind of recycling is fundamental to sustainability for two...
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