DYNAMIC ECOSYSTEM

Ecology – the scientific study of the interactions among organisms and the interactions between the organisms and their environment

Environment

Biotic component

Living organisms

Abiotic component

Non-living factors

-pH value

-Temperature

-Light intensity

-Humidity

-Topography

-Microclimate

pH

Most organisms survive well in neutral environment

Aquatic organisms are sensitive to changes of pH

Humidity

The amount of water vapour in the air Affect the rate of water loss in plants

Low Humidity –water evaporates faster from a surface

High humidity – at night Low humidity – daylight

Light intensity

Affects the distribution of plants and animals

Shallow water fish

Deep sea animals

Varying light intensity in a forest leads to the growth of different types of plants

Tall trees – exposed to greater light intensity- small plants grow undercover from the

canopy of tall trees - animals also live under the cover of

the tall tree

- mosses, small animals – live in low light intensity

Temperature

Affect the physiological activities of plants and animals

Most living organisms live within narrow range of temperature

Temperature higher than 45o C lead to denaturation of enzymes within organisms

Topography

Physical land features such as altitude, gradient, aspect of the region

Main topographic factor – altitude

Higher altitudes – lower atmospheric pressure and temperature

Different types of plants at different altitude

Gradient – steepness of a slope- steep slopes – more drainage and runoffs - not suitable for organisms

Aspect of a slope - windward mountain slopes receive

more rains than leeward slopes - different type of organisms live on

these two area

Microclimate

Climate in micro habitat Includes – humidity, temperature, light

intensity, atmospheric conditions

Biotic components

Primary source of energy – sun

Living organisms

Producer Consumer Decomposers

Producer Autotroph – synthesise organic

substances or food from nutrients and sunlight

Produce food for other organisms

Consumer – cannot produce its own food - feeds on other organisms

Primary consumer – herbivoresSecondary consumer – carnivores Tertiary consumer – carnivores that prey

on secondary consumer

Food chain – the feeding relationship between living organisms in an ecosystem

- shows the transfer of energy from the sun

Each category of organisms in a food chain is known as a trophic level

Pyramid of numbers – shows the number of organisms at each trophic level

The number of organisms decrease but the size of organisms increase

The food chains in a community are usually interconnected to form a food web

Energy flow within a food web

Energy is transferred from one trophic level to the next

Producer

-Convert solar energy to chemical energy

Decomposer

- Transfer energy to the soil

Primary consumer

-10% of the energy is transferred to the primary consumer

-- 90% lost to the environment

Cellular respiration

- For growth and movement, heat

Excretion and defaecation

Some energy is transfer to the decomposer

Secondary consumer

- Receive energy from primary consumer

Sun

At each ascending trophic level, the total energy level decrease along the food chain

This explain why food chains are short

Short food chain – more energy for the consumer

Food chains rarely have more than four trophic levels

Interactions between biotic components

Interactions between organisms

saprophytism Prey-predator

competitionsymbiosis

Commensalism mutualism parasitism

Symbiosis- Close interactions between two different

species which live together and interact with each other for an extended period of time

One species always benefits while the other species may be unaffected, harmed or helped

Three categories of symbiotic:1.Commensalism

- commensal partner gets benefits while the host derives neither benefits nor harm

Examples – remora fish and shark- remora fish gets free transportation,

feeds on food scraps from the shark

Epiphytes – plants which grow on other plants but do not obtain food from the host

- orchids obtained sunlight- the host plant are not affected and do not get benefits

Epizoics – animals which live on the body of other animals

- barnacles get a free ride while looking for food- the whale are not affected

2. Mutualism- a relationship between two species of organisms in which both organisms benefit

Examples :- A lichen – mutualistic relation of an alga

and a fungus

Fungal hyphae

Algae cells

- green alga produces food for itself and for the fungus - alga is protected and sheltered from

drying out by fungus

- fungus supplies carbon dioxide and nitrogenous compounds for the algae to manufacture food

- Plant in legume family (peas, bean)- host to mutualistic bacteria - Rhizobium sp. Live inside the root

nodules of leguminous plant

- nitrogen fixing bacteria convert atmospheric nitrogen into ammonium compounds that are used by the plants

- plants provide the bacteria with organic compounds

3. Parasitism - a symbiotic relationship in which one organisms benefits while the other is harmed

- organisms which benefits is the parasite which derive its nutrition from the host which is harmed in the process

- harming or weakening the host- smaller than the host

Examples :- Ectoparasites – parasites that feed on the

external surface of the host - Mosquitoes, aphids, fleas

- endoparasites – live within the tissue of their host

- tapeworm – attach to the digestive system of the host

Saprophytism

A types of interaction in which living organisms obtain food from dead and decaying organic matter

Saprophytic bacteria and fungi secrete digestive enzymes to digest dead organisms before absorbing the nutrients

Examples – Mucor sp., mushroom

Prey predator

Organisms or the prey is hunted and eaten by a stronger and bigger organisms called the predator

Examples :- tiger, lions, eagles

The prey predator relationship is stable The prey and predator regulate the

population of each other in a dynamic equilibrium

Increase the size of the prey population

Number of predators increases

Fall in the population of prey

The prey population returns to the level at which it fluctuates

Level at which the prey population starts to fluctuate

Fall in the prey population

Number of predators decreases

Increase in the size of prey population

Prey predator

Interaction between organisms which live together in a habitat and compete for the same resources that are in limited supply

The competition between individuals of the same species is called an intraspecific competition

The competition between individuals of different species is known as an interspecific competition

The intraspesific competition is more intense because the needs for nutrients, shelter, light and other resources are identical

Organisms which are weak will migrate or die

Example :intrespesific competition between the populations of Paramecium aurelia and Paramecium caudatum

Species which are stronger and have better adaptations are usually more successful and survive the competition

Paramecium aurelia grows faster than the Paramecium caudatum

P. aurelia reproduces at a faster rate and has a competitive edge in obtaining nutrients

The processes of colonisation and succession in an ecosystem

Ecosystem – a community of living organisms interacting with one another and with the non living environment

Ecosystem are dynamic Biotic communities – changing

- response to – climate, internal factors

Ecological terms

Habitat - Natural environment in which an

organisms live - Provides – food, shelter, living space,

breeding site

Species - Group of organisms that look alike and

have similar characteristics, share the same ecological niche, capable of interbreeding and producing fertile offspring

Population - A group of organisms of the same species

living in the same habitat at the same time

Example : population of elephants living in the jungle

Community - A natural collection of plant and animal

species living within a defined area or habitat in an ecosystem

Members of community interdependent and interact with one another

A change in the population will affect the population and distribution of other species within the communities

Niche - The function of an organisms or the role its

play in an ecosystem is known as ecological niche

Includes its habitat, interactions with other organisms, the types of food it consumes, the range of temperature

Example :the niche of grass is as producer of carbohydrates and organic substances which provide food for other organisms

Colonisation and succession

Environment of bare rocks and sand left behind by forest fire is not suitable for most organisms

When air, water, nutrients ad sunlight are available spores and seeds of certain plants start to germinate and grow

This is called colonisation

Pioneer species – the early colonisers that appear on a bare patch of ground without soil

- hardy species – grasses, fern - have special adaptations which

enable them to survive in dry and nutrient poor soil

- change the environment that favour subsequent communities

Adaptations of pioneer species - Produce large number of easily dispersed

seeds to help them colonise space

Dense root system bind the sand and soil particles together and hold water and humus to improve the structure of the soil

- Have a short live cycle – die, the remains add to the humus content of the soil

Pioneer species modify the environment, creating conditions which are favourable for other species called successor species

Successor species grow larger and gradually shade the original pioneer species and replacing it

Example :- herbaceous plant (dandelions and weeds)

Successor adaptations :- small wind dispersed seed which can spread, germinate and grow rapidly

Successor species change the structure and the quality of the soil

Shrubs become the new dominant species

Shrubs modify the environment – enables large trees to grow

Large trees provide shade – shrubs cannot compete – replaced by forest floor species (low light intensities)

Succession – gradual process in which one community changes the environment so that it is replaced by another community

Succession take hundreds of years- lead to stable community - in equilibrium with the environment

- climax community

Example of climax community – rainforest Climax community – stable, mature, little

or no changes in its species structure

Mangrove swamp

Found in the tropical and subtropical regions where fresh water meets salt water

Hostile environment for normal plants – low level of oxygen

- high concentration of salt - high intensities of sunlight - strong winds - strong wave

Adaptations of mangrove plants

Highly branched underground cable roots - Avicennia sp.

Prop roots (aerial roots) – Rhizophora sp.- anchor plants to the muddy soil

Breathing roots (pneumatophores) – grow vertically upward - numerous pores for gas exchange during low tides - lenticels (pores) on the bark of the

tree – for gas exchange

The leaves - covered with thick layer of cuticle –

reduces transpiration during hot days - thick and succulent , able to store water

Cell sap in the root cells has higher osmotic pressure than the soil water surrounds them - roots do not lose water by osmosis

Salt is excreted from hydathodes (pores on the lower epidermis of the leave) as crystalline salt

Mangrove seeds are able to germinate while still attached to the mother plant – Viviparity- increase the survival of the mangrove as

the seedlings can float horizontally

Zonation of mangrove swamps

The pioneer species of a mangrove swamp are Sonneratia sp. and Avicennia sp.

The extensive root systems trap and collect sediments, including organic matter from decaying plant parts

As time passes, soils become more compact and firm

This condition favour the growth of the Rhizophora sp.

Rhizophora sp. replaces the pioneer species

Prop root system of Rhizophora sp. Traps silt and mud, creating a firmer soil structure #135. Slide 135

The ground become higher. Soil become drier

The condition becomes more suitable for Bruguiera sp.

This species replaces the Rhizophora sp.

The buttress root of the Bruguiera sp. Forms loops which extend from the soil to trap more silt and mud

More sediment are deposited and the shore extend further to the sea

Over the time , terrestrial plant – nipah (Nypa fruticans) and Pandanus sp. begin to replace the Bruguiera sp.

The transition and succession from mangrove swamp to a terrestrial forest and eventually tropical forest takes a long time

Tropical rainforest – climax community

colonisation and succession in a pond

pioneer species -phytoplankton, algae &

submerged plant-Hydrilla sp., Cabomba

sp, Elodea sp.

pioneer species die and decompose – becomes

organic matter & converted into

humus

humus and soil erode from the sides of the pond – deposited on the base of thepond - shallower conditions become

unfavourable for submerged plants - more suitable for floating plants

adaptive characteristics of pioneer : - fibrous root penetrate deep into the soil - bind and particles together

floating plants - duckweeds (Lemna sp.), water

hyacinth (Eichornia sp.), lotus plant

(Nelumbium sp.)

receive enough sunlight - reproduce rapidly

- spread and cover large area

- prevent sunlight from reaching

submerged plants

lack of sunlight – submerged

plants dies

decompose remains of submerged plants

add organic matter to the

baseof the pond

ponds become shallower unsuitable

for submerged plants

erosion occurs at the edge of the pondsmore sediments

deposited on the base of the

ponds

emergent plants replaced the

floating plants

live in water e.g. sedges, cattails

rhizomes grow horizontally – bind

soilparticles together &

absorb more mineral salts

emergent plants grow from

the edge to the middle of the

pond

plants die, decomposed remains add to the sediments

o the base of the pond -

shallower

condition of the pond becomes

favourable for land plants

herbaceous weeds: Ageratum conyzoides,

Euphorbia hirta, Oldentandia dichotoma land become drier – land plants

such asshrubs, bushes, woody plants

becomesnumerous

Primary forest emerges turns into tropical

rainforest – climax community

Population Ecology

Population – a group of organisms of the same species occupying a particular area or habitat

various factors determine the size of a population :

- abiotic factors -biotic factors -birth rate -death rate -immigration, emigration

to study the dynamic of a population ecologist need to estimate the population size

Sampling techniques allow ecologist to estimate the total population sizes and densities

Quadrat Sampling Technique

used to study plant populations or populations of immobile animals

consist of a square or rectangular frame made of metal or wood

strings are used to subdivide the quadrat into smaller squares

the size of the quadrat depends on the size, distribution and density of the organisms being studied

a number of quadrats are set up randomly throughout the area being studied

the species present within the frame is counted and the number is recorded

frequency of species : number of quadrats containing the species X 100% number of quadrats sampled

Density of the species : total number of individuals of a species in all quadrats number of quadrats sampled x area of each quadrat sampled

Percentage coverage :

aerial coverage of all quadrats (m2) x 100% number of quadrats sampled x quadrat area

Capture, mark, release and recapture technique

used to estimate the population sizes of mobile animals such as mammals, birds, butterflies, woodlice and other insects

a specific animal sample is captured and marked with a ring or tag with water proof coloured ink, cellulose paint or nail varnish

the marked animals are then released into the general population

after a few days and weeks a second animal sample is captured and the number of marked animals in the second sample is counted and recorded

Population size : number of organisms in the first sample x number of organisms in the second sample number of marked organisms recaptured

this technique assumes : - the marked animals are not harmed or predated upon - the animal population under study is stable – no mortality because of disease,

no immigration or emigration

- the marked animals mix freely in the population

- marked individual has the same probability of being recaptured

to ensure the results are more accurate : - capture large samples - animals must be captured randomly - enough time must be given for the marked

animals to mix with unmarked animals

the marked used must be permanent and not easily detected by predators or hinder the animals movement

Abiotic factors which influence the population distribution of an organisms

temperaturelight intensity humiditypHaspect

Biodiversity

refers to the diverse species of plants and animals in different ecosystem on earth

Taxonomy is the branch of Biology concerned with the identification, naming and classification of organisms

Classification is necessary so that organisms can be easily and accurately identified

enables scientist to communicate accurately and precisely with one another

organisms

monera Protista Fungi

Plantae Animalia

Monera

unicellular organisms have cell wallno membrane for organelles and nucleus genetic material scattered in the

cytoplasm

examples – cyanobacteria (blue green algae), bacteria

cyanobacteria and certain bacteria can carry out photosynthesis

Bacteria's shape:

1. rod

2. round

3. spiral

Protista

includes algae and protozoa nuclei and membranes surrounded by

membranes

plant like protist – green algae – have chloroplast

heterotrophic or autotrophic

the cells of multicellular protist are not specialised to perform specific function within organisms

Examples : Amoeba sp., Paramecium sp., Spirogyra sp., Trypanosoma sp.

Fungi

mostly multicellular organisms cell wall of fungi contain chitin main bodied consist of a network of thread

like hyphae called micelium

saphrophytic have ni chlorophyll, obtain energy by

decomposing decaying organisms and absorbing its nutrients

examples – moulds (Mucor sp.), mushrooms, yeasts

Plantae

immobile, multicellular organismsproduce food through photosynthesis

plant cells are enclosed in cellulose cell walls

Animalia

multicellular heterotrophic organisms do not have rigid cell walls and chloroplastmostly carry out locomotion usually digest their food internally

Hierarchy in the classification of organisms

Living organisms are classified according to their basic characteristics

Kingdom

Phylum

Class

Order

Family

Genus

Species

A kingdom consists of group of organisms sharing certain common organisms

the largest unit of classifications

contains largest number of organisms

the number of organisms at each level decreases as we go down along the hierarchy

the naming of organisms is based on the Linnaeus binomial system

each organisms has two names in Latin

the first name is the name of the genus begins with a capital letter

the second name begins with a small letter refers to the name of the species

examples :

Homo sapiens – human

Homo sapiens

Kingdom – Animalia

Phylum – Chordata

Class – Mammalia

Order – Primates

Family – Homonidae

Genus – Homo

Species – sapiens

Bunga raya – Hibiscus rosa-sinensis

Oil palm – Elais guineensis

Durian – Durio zibenthinus

Frog – Bufo melanostictus

Paddy – Oryza sativa

Rambutan – Nephelium lappaceum

The importance of biodiversity

1. Provide various biological products

- food, medicine, timber, spices

2. Provides many environmental services to humans and other species

- pollination, nutrient cycling, regulation of the atmospheric composition

3. All species are supported by the interactions among other species and their ecosystem for food, shelter and other basic need

4. Diversity in genetic pool

Microorganisms

5 types :

1. Virus

2. Bacteria

3. Algae

4. Protozoa

5. Fungi

Bacteria

size 0.5 -5.0 micro meter

Unicellular

has cell wall, plasma membrane, DNA is enclosed in a membrane

Cell wall – made from peptidoglycan (protein + polysaccharide)

form spores under unfavourable conditions

Shape – spherical (coccus)

rod (bacillus)

spiral (spirillum)

Comma shaped (vibrio)

Examples – Lactobacillus sp.,

Staphylococcus sp.

Algae

Photosynthetic, plant like

Cell wall – cellulose

No leaves, stem roots

Examples – phytoplankton, Spirogyra sp.

Fungi

Heterotrophic

Do not have chlorophyll, stems, roots, leaves

Cell wall – chitin

Feeding – secrete enzymes that break down organic material into simple molecules before absorbing them

Examples – yeast, Mucor sp.

Protozoa

Unicellular

Have nucleus, cytoplasm, plasma membrane

Carry out life process – respiration, reproduction, excretion

Moves – flagella, cilia, microtubules

Examples – Euglena sp., Paramecium sp, Trypanosoma sp.

Viruses

can only be seen by electron microscope

non living cell

cannot survive or reproduce outside the cells of its host

Infectious

Utilise the cellular machinery of the host to make copies of itself

two basic parts:

1. Inner core – composed of nucleic acid

(DNA or RNA)

2. Capsid - protein

Can be purified and crystallized

Examples – T4 bacteriophage, tobacco

mosaic virus

The effects of abiotic components on the activity of microorganisms

1. Nutrient and water

- for reproduction and growth

- without nutrient and water -die, spores

2. pH

- most bacteria – alkaline conditions (pH

7.4 )

- Yeast & protozoa – acidic conditions (pH 4.5-5.o)

- Extreme pH – destroy bacteria

3. Temperature

- inactive at low temperature

- Optimum temperature – 35-40 C

- Beyond 60 C – growth of microorganisms inhibited

- destroyed – sterilised at 121 C

Light intensity

Prefer dark or low light intensities

High intensities or UV – kill microorganisms

Photosynthetic algae and bacteria – active under high light intensities – photosynthesis

The role of useful microorganisms in the ecosystem

Atmospheric nitrogen cannot be absorbed directly by plants

Plants use nitrogen in the form of ammonium, nitrite or nitrate ions from soils

Nitrogen fixing bacteria can assimilate atmospheric nitrogen into ammonium compounds (NH3 and NH4+) - process called nitrogen fixation

Nitrogen fixing bacteria :− Nostoc sp. - live in the soil

− Rhizobium sp. - in the roots nodules of leguminous plants

Nitrates – taken by plants roots – converted into plants protein

Nitrate Plants Animals - animals protein

waste matter Plants Animals

decompose

ammonium compounds

Nitrosomonas sp. - oxidised ammonia

into nitrites

Nitrobacter sp. - oxidised nitrites into nitrates

Nitrate in soil denitrification – by

denitrifiying bacteria

bacteria break downnitrates into gaseous nitrogen and oxygen

oxygen used by bacteria

Nitrogen returned to atmosphere

Decomposition

Decomposers – organisms that secrete digestive enzymes to break down organic matter and animal wastes into simple molecules

simple molecules – carbon dioxide, water, ammonium

- used by autotroph – green plants

Main decomposers – saprophytic bacteria

- return nutrient in organic matter to atmosphere,

soil and water

return back nutrient to the soil – soil becomes fertiles

The alimentary canal of termites :

- mutualistic protozoa – Trichonympha sp. secrete

cellulase enzyme

- help termite digest cellulose

Digestive system in humans :

- symbiotic bacteria synthesis vitamins B12 and K

The harmful effects of microorganisms

lead to spoilage of food and substances and cause diseases

Pathogen – microorganisms that cause diseases

- only cause disease if it can get into the body cells

Methods in the transmission of disease

1. water and food

- contaminated food or drinks

- through faeces of infected people

- unwashed hands

-example – typhoid, cholera

2. Airborne and droplet transmission

- enter the body through the respiratory system

- liquid droplet containing virus or bacteria from

sneeze and cough of infected person- droplet transmission

- spores of bacteria can be transmitted by air

- airborne transmission

3. Vectors

- mosquitoes, flies, cockroaches

- vectors are the carrier of the disease

- mosquito (Anopheles sp.) - carries protozoan

(Plasmodium sp.) - malaria

-houseflies – cholera – food poisoning

4. Direct contact

- contact with infected person or personal items of

infected person

- tinea or ringworm

- AIDS, syphilis,gonorrhea

Methods controlling pathogens

1. Antibiotics

-penicillin, streptomycins

- produced by microorganisms

- used to kill other microorganisms

2. Vaccines

- modified or weakened forms of viruses or dead

bacteria

- injected into the body to induce the production of

antibodies

-examples – BCG, Sabine vaccine

3. Antiseptics

- chemicals that inhibit the growth of

microorganisms

-prevent infections of wound

- examples – acriflavin, iodine solution

4. Disinfectents

- solutions used to kill microorganisms on the

surfaces of floor, building or furniture

-for sterilised surgical equiment

-examples – phenol, formaldehyde, carbolic acid

The use of microorganisms in biotechnology

Biotechnology – the application of organisms or microorganisms or biological processes in the production of materials for use in medicine and industry

1. Production of antibiotics, vaccines and hormones

- Antibiotics – produced by Streptomycines sp.

(streptomycin) and Penicillium chrysogenum

(penicilin)

- vaccine -sabine vaccine used to treat poliomyelitis

- Genetically modified bacteria – produce insulin

2. Production of energy from biomass

(a) Biogas

- gas produced by anaerobic fermentation of organic matter

or waste

- used in vechicles

(b) Biofuel

- combination of 10% ethanol and 90% petrol

- main source – sugar cane, maize

- glucose and sucrose extracted from these plants

- fermented by yeast to produce ethanol

- ethanol can be used for vehicles

3. Cleaning of oil spill

- genetically engineered bacteria convert oil into

less harmful molecules

4. Waste treatment

- waste treatment plant – aerobic bacteria

decompose organic matter in sewage in the

presence of oxygen

- anaerobic bacteria continue to decompose organic matter to methane and carbon dioxide

-methane gas is collected and used as fuels for engines pumps in the sewage plants

- digested sludge – rich in nitrates and phosphate can be used as fertilisers

5. Production of biodegradable plastic (bioplastic)

- Bioplastic can be broken down into inorganic

compounds by certain bacteria

culture bacteria in

nutrient rich

medium

specific nutrient (nitrogen)

is depleted from

cultured

medium

bacteria reacted by producing

bioplastic as storage

component in their cells applications – credit cards,

bottles

6. Food processing

- microorganisms is used for fermentation process

- Bread making (flour, sugar) – yeast (Saccharomyces cerevisiae)

- Beer making (barley)– S. cerevisiae & S.

carlsbergensis

- Wine (grape)

-soya sauce – fermentation of soya beans by fungi

- Yogurt – fermentation of milk by Lactobacillus

bulgaricus & Streptococcus thermophillus

- convert sugar into lactic acid which coagulate casein and producing thick creamy yogurt

- cheese – mixing bacteria with rennin- bacteria ferment milk sugar to lactic acid

- solid part of the milk is separated from the liquid portion

-the solid part are pressed and mould and left to mature

Appreciating Biodiversity

1. Conservation – efforts made in maintaining the quality of the natural environments and their biological resources

- replanting trees

2. Preservation – efforts in protecting the diverse ecosystem and wildlife species of earth which are threatened with extinction