Download Integrated Programme Sec 2 SBGE, LSS Biology Module Topic 3.1

Integrated Programme
Sec 2 SBGE, LSS Biology Module
Topic 3.1 Introduction to Ecology
A. Introduction
B. Habitats and Biomes
C. Habitats and Physical Factors
a. Air
b. Water
c. Temperature
d. Light
e. Minerals
f. pH
D. Understanding the Ecosystem
E. Man’s Impact on the Environment
F. Importance of Nature Conservation
Ecology Notes Prepared by Mrs Cheryl Siah
A. Introduction
a. Study of Ecology
i. Interactions of living organisms with other living organisms (biotic
environment)
ii. Interactions of living organisms with physical environment (abiotic
environment)
iii. Adaptations of living organisms for better survival
b. Population
i. Group
e.g.




of organisms of the same species living in a particular habitat
Arctic fox in Arctic Tundra
Arctic willow in Arctic Tundra
Orang utan in rainforests
Cinchona tree in rainforests
Arctic Fox
Arctic Willow
c. Community
i. All the populations of organisms living and interacting with one another in
a particular habitat that make up a community
ii. E.g. orang utans, cinchona trees, hornbills and tembusus form a
community in a rainforest populations live interdependently any change in
one population affects the other populations
Rainforest Community
Ecology Notes Prepared by Mrs Cheryl Siah
B. Habitats and Biomes
a. Habitats
i. Place where organism lives in
ii. E.g. arctic tundra
icy cold environment throughout the year
northern hemisphere


b. Biomes of the World
i. Fresh Water Biomes


Low salt (less than 1%)
Supply of drinking water
1. Ponds and lakes
a. Upper littoral zone
 Warm, well-lit and shallow
 Floating plants and larvae found here
 Grazing snails, fish, amphibians, clams and
crustaceans, ducks, turtles and snakes
b. Limnetic zone
 well lit
 Planktons and freshwater fish
c. Deeper profundal zone
 Little light and cold
 Organisms here eat dead organic matter
2. Streams and rivers
a. Single direction water flow
b. Clear, cool and high oxygen content
3. Wetlands
a.
b.
c.
d.
e.
Standing water areas which support aquatic plants
Moist and humid
Hydrophytes found here
Highest biodiversity
Amphibians, reptiles and birds
ii. Marine Biome
1. Oceans
a. Largest body of water
b. Great diversity of living organisms
c. Very large effect on global climate
2. Intertidal zone
a. Earth meets land, waves come in and out
b. Very few algae and plants
c. Predatory crustaceans, crabs, worms, clams and shorebirds
3. Pelagic Zone
a.
b.
c.
d.
Ecology Notes Prepared by Mrs Cheryl Siah
Open ocean
Generally cold
Floating seaweeds found here
Many species of fish, some mammals (whales and dolphins)
4. Benthic zone
a.
b.
c.
d.
Temperature decreases as depth increases
Bottom – sand, silt and dead organisms
Dark – not much plants except some seaweed
Nutrient rich – hence bacteria, sea anemone, sea stars and
warms, sponges and fishes found here
5. Abyssal zone
a.
b.
c.
d.
e.
Very cold
Very dark
High pressure
Hydrothermic vents
Chemosynthetic bacteria found here
6. Coral Reefs
a. Warm shallow water
b. Nutrient poor water
c. Found as barriers around continents
e.g. Great Barrier Reef in Australia
d. Fringing islands and atolls
e. Dominant fauna – corals
 Made up of animal polyps and algae
 Algae can photosynthesise
 Animal polyps can “capture” planktons
f. Fish, micro-organisms, invertebrates, sea stars, sea urchins
and octopi are found here
7. Estuaries
a. Freshwater streams and rivers merge with ocean
b. Varied salt concentration in water
c. Algae, seaweeds, mangrove plants and marsh grasses found
here
d. Waterfowl, crabs, shrimps and oysters are found here
(more reading – http://www.ucmp.berkeley.edu/exhibits/biomes/index.php)
iii. Forests (in particular Tropical Rainforests)
a. Warm and wet
b. Rapid decomposition
c. Very diverse in species – half of the world’s 10 million species
found in the tropical rainforests!
d. e.g. Amazon
iv. Deserts (in particular Hot and Dry Deserts)
a. Very hot day
b. Very cold night
c. Only short bursts of very little rainfall in between long periods of
rainless days
d. Plants are ground hugging shrubs and short woody trees
i. Leaves are very reduced – needle like
ii. Stems are green and photosynthetic
iii. Stomata only open at night
 prevent excessive water loss
e. Animals are active only at night
f. Animals may practice aestivation
g. Lowering of metabolism
h. e.g. Sahara
Ecology Notes Prepared by Mrs Cheryl Siah
v. Grassland (in particular Savanna Grassland)
a.
b.
c.
d.
e.
Hot and wet
Rainfall separated by long periods of drought
Violent thunderstorm followed by strong drying winds
Loose soil with high drainage of water
Consists of the most number of species among the different types
of grassland
f. Abundance of grass interspersed with lone trees/shrubs
g. Frequent fire
h. Deep roots of grass not damaged by fires
i. Roots with starch reserves for new growth
ii. When rain comes, vigorous growth of grass
iii. food available, animals reproduce
i. Fires that kill insects create a “feast” for small animals
vi. Tundra (in particular Arctic Tundra)
a.
b.
c.
d.
e.
f.
g.
h.
i.
Coldest biome
Treeless
Frost covered plain
Very little rainfall
Poor nutrients
Short season of growth and reproduction
Energy and nutrients mainly in dead organic materials
Low shrubs, sedges, reindeer mosses, liverworts, and grasses
crustose and foliose lichen
i. mammals with long thick layer of hair and blubber for
insulation
ii. animals can hibernate
iii. migratory birds
No reptiles and amphibians (unable to regulate internal
temperature)
Tundra Environment
Ecology Notes Prepared by Mrs Cheryl Siah
C. Habitats and Physical Environment (Abiotic Environment)
a. Air
i. Quality of air
1. Presence/absence of pollutants
ii. Content of oxygen
1. most organisms are aerobic
2. cannot survive in low oxygen environment unless specially adapted
e.g.
 mangrove trees with pneumataphores
 lungfish living in African Mudflats
b. Water
i. Availability of water
1. Dependant on rainfall
2. Some plant specially adapted for little rainfall
e.g. xerophytes
3. Some plants adapted for wet environment
e.g. hydrophytes
ii. Quality of water
1. Presence / absence of pollutants
2. Clarity of water (affects amount of sunlight penetrating water)
c. Temperature
i. Affects metabolism and physiological activities
1. Activities controlled by enzyme
a. Enzymes are temperature sensitive
b. Beyond optimal temperature, enzymes are denature
d. Light Intensity
i. Affects growth of plants
ii. In dim light

Plants develop adaptation to get more light

Plants need to adapt to block off excessive light to block out
excessive heat too
iii. In excessive light
e. pH
i.
ii.
iii.
iv.
measures acidity and alkalinity of solution
in relation to soil water or water bodies
affects types of organisms living in environment
decrease in alkalinity can be caused by photosynthesis that removes
carbon dioxide from water
v. increase in alkalinity can be caused by respiration rather than
photosynthesis as carbon dioxide is removed
f. Minerals
i. Availability of minerals in soil or water
ii. water with high concentration of salt/minerals (e.g. salt water) can
cause living organisms to lose water
iii. living organisms need to have special adaptations to prevent water loss
iv. freshwater organisms have tendency to gain water
Ecology Notes Prepared by Mrs Cheryl Siah
v. living organisms need to have special adaptations to prevent excessive
entry of water
vi. brackish water


mix of salt water and fresh water
changes in salt concentration is high (large fluctuations)
D. Understanding the Ecosystem
a. living organisms (biotic)
b. non-living (abiotic) environment
c. Interaction of biotic and abiotic environment
i. Ecological equilibrium means a biological balance in the relationships
between the biotic and abiotic factors
ii. Selective addition or removal of organisms affect the equilibrium and
affects all other populations
1. External introduction of species can affect native species (naturally
found in a particular habitat) E.g. cane toads brought in to control
beetles which were destroying sugarcane crops harm native wildlife
by eating the small animals and poison predators which try to eat
them
2. More examples:
http://www.environment.gov.au/biodiversity/invasive/ferals/index.html
iii. Problems Related to Introduced species
1. No natural predators
a. Can multiply out of control
b. Introduced species can predate on native species
c. Introduced species spread diseases to native species
d. Introduced species can destroy the habitats of native
species
e. Introduced species can compete with native species for
food, water and shelter
Ecology Notes Prepared by Mrs Cheryl Siah
E. Man’s Impact on the Environment
a. Human activities have continually depleting the earth’s natural environment
e.g. fossil fuels
b. Ecological equilibrium can be upset
c. Damages can be long lasting
d. Deforestation
i. Felling of trees in the forest for
1. Industrialization
2. Fuel
3. Farming
4. Making paper
ii. Results in:
1. Loss of habitats for the living organisms
2. Soil erosion
a. Lack of canopy coverage to cushion impact of rain
b. Lack of roots to hold the soil
c. Top soil gets washed away
3. Flooding
a. Eroded soil enter rivers
b. Blocking of water flow
c. Water level rises and floods over
4. Climate changes
a. Water evaporates very fast when there is no canopy
coverage
b. Area becomes very dry and warm
i. Less rainfall
e. Uncontrolled fishing practices
i. Over fishing leads to declining fish/marine life populations
1. Due to destructive fishing methods
2. Fish populations do not replace fast enough
 Extinction
f. Pollution
i. Contribution of substances that damage the environment
ii. Water Pollution
1. Untreated sewage
2. Pesticides washed into water
3. Eutrophication
a. Washing of fertislisers into water
i. Profuse growth of algae which blocks sunlight
ii. Submerged algae and plants die
iii. Bacteria multiply rapidly and compete for oxygen
 death of aquatic species
iii. Bioaccumulation
1. Accumulation of poisonous chemicals through the food chain and
concentration of chemicals in top of food chain.
Ecology Notes Prepared by Mrs Cheryl Siah
F. Importance of Nature Conservation
a. Many undiscovered species that can be beneficial to mankind (half of the
world’s 10 million species found in the tropical rainforests!)
i. Harvesting of useful drugs
1. Potential cure of many illnesses/diseases
2. E.g quinine extracted from bark of Cinchona – antimalarial drug
ii. Economically important species
1. Sources of raw materials for industries
a. e.g. rattan for furniture
b. e.g. fibres from cotton to make cloth
2. food
(http://www.integratedconservationresearch.org/ICRIFiles/RainforestProducts.htm)
b. Prevent species from reaching threatened or extinction status
i. Maintain stable and balanced ecosystem
ii. Prevent disruption of natural cycles (KIV)
c. Prevent global warming
d. Maintain a large gene pool
i. Favourable genes in living organisms can be harvested to improve other
living organisms
1. Improve agricultural produce
2. Make living organisms and man more resistant to diseases
e. Conservation of marine life
i. Source of food
f. Maintain natural resources for outdoor recreational activities
g. Conservation of rainforest
i. Source of fresh drinking water supply
ii. 1/5 of world’s supply moves though the Amazon Basin!
Ecology Notes Prepared by Mrs Cheryl Siah