CHAPTER 4: INTERDEPENDENCE AMONG LIVING ORGANISM & THE ENVIRONMENT

4.1 Species, Population, Community, Habitat and Ecosystem

a) Species A group of organisms (animals or plant) with same shape and structure and breed among themselves to produce fertile offspring.

Figure 4.1.1 Example of 3 different species

b) Population A group of organisms (animal or plant) of same species live together in a habitat. Example: A group of monkey on a tree and a group of coconut tree at the field.

Figure 4.1.2 An example of a population of zebra.

c) Community Made up of different populations (animals or plants) living together in a particular habitat. For example: a population of big fishes, shrimps and water weeds living together in the pond.

d) Habitat The area where the organism lives and reproduces. Examples: Sea, pond, forest, desert and paddy field.

e) Ecosystem Community of living organism (biotic) living in same habitat, together with non-living environment (abiotic). Example of non-living environments (abiotic) are water, soil, air mineral, light and temperature.

Figure 4.1.2 An example of an ecosystem at a pond.

Interdependence of living thing organisms create a balanced ecosystem

All living organism are interdependent on one another for survival. For example:

1. Plants depend on non-living thing such as light, water & carbon dioxide to make food.

2. Animals need plants for food and oxygen.

3. Some organisms depend on other organism for food, protection or shelter. The interdependence among living organism and also the environment creates a balanced ecosystem.

4.2 Types of interaction between living organism

There are 3 types of interaction between living organisms:

1. Prey-predator

2. Competition

3. Symbiosis

a) Prey and predator A relationship where an animal (predator) hunt and eat other animal (prey) for food. Example of the interactions are:

Sparrows and worms

Owls and rats

Tigers and rabbits

b) Competition A relationship occur when organism (animals and plants) compete for limited resources.

Animals compete for food, water, living space and mate for reproduction.

Plants compete for sunlight, water, air, minerals salts and living space.

There are 2 types of the interactions:

Intra-specific competition (competition among same species)

Inter-specific competition (competition among different species)

c) Symbiosis The close interaction between two different organisms.

There are 3 types of symbiosis:

1. Commensalisms A relationship between two organisms which one of the organism (commensal) get benefits from another (the host). And the host is not affected or harmed.

Examples of commensalisms:

Remora fish (commensal) attach to a shark (host) to get transport and food.

Barnacles (commensal) live on the body of crabs (host) to get transport and food. The crabs are not affected.

Ferns for example Pigeon Orchid, Bird nest or Staghorn grow on the branches of big trees (host) to get support & enough sunlight. And the tree is not affected.

2. Mutualism A relationship between two organisms which both organisms get benefits from another.

Examples of mutualism:

Sea anemone attaches itself to the shell of hermit crab (host). Sea anemone gets food and transport while the hermit crab is protected by stinging tentacles of the sea anemone.

Lichen consists of a fungus and a green alga that living together. The fungus gets food from alga & alga is protected by fungus.

Nitrogen-fixing bacteria & leguminous plants. Nitrogen-fixing bacteria convert nitrogenous compound for plant to make protein while leguminous plants give food and shelter for bacteria.

Herbivores like rabbits and cows have anaerobic bacteria in the intestines. The bacteria produce enzyme to digest cellulose & the herbivore (host) give shelter & food for bacteria.

3. Parasitism A relationship between two organisms which one of the organism (parasites) gets benefits from another (the host). And the host is harmed or may eventually die.

Examples of parasitism:

Fleas, ticks & mosquitoes (parasites) suck blood from their hosts (animals) and will cause diseases.

Fungi, Rafflesia & Aphids (parasites) suck nutrient & water from plants (host) and kill them finally.

Tapeworms or threadworms (parasites) live in human or animal (host) intestines and suck the nutrients, cause the host to fall sick eventually.

Biology Control

a) Effective way to control pests.

b) Use the prey-predator relationship to control pests.

c) For example: Use owls and snakes to reduce the number of rats in the oil palm estate.

d) The advantages of using biology control are:

Do not cause pollution

Safer and cheaper

e) The disadvantages are:

Take longer time

May kill other organism that are useful

Might become nuisance

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4.3 Food Webs

a) Producer, consumer & decomposer.

Producer All green plants that can make their own food through photosynthesis process. These organisms are calledautotrophs.

Consumer Animals that eat plants or other animals to get energy they need.

They are 3 types of consumers:

1. Primary consumer Animals that eat plants (herbivore)

2. Secondary consumer Animals that eat plants or primary consumer (carnivore/omnivore)

3. Tertiary consumer Animals that eat secondary consumer (carnivore)

Decomposer Organisms that decaying dead animals or plants into simplest molecules. (bacteria &

fungi)

b) Food chain describes a single pathway which energy in the food passed from producer to consumers. For example:

Grass Caterpillar Sparrow Eagle

An example of food chain is shown below:

Producer Primary consumer Secondary consumer Tertiary consumer

c) Food webs A food web is formed by two or more interconnection of food chains.

(Caterpillar) (Sparrow)

(Eagle) (Grass)

(Fox) (Snail)

(Grasshopper)

(Rabbit)

An example of a food web is shown below:

(Producer) (Tertiary consumer) (Primary consumer) (Secondary consumer)

d) Pyramid of numbers

(Grass (Producer)) (Rabbits (Primary consumer)) (Eagle (Tertiary consumer)) (Snakes (Secondary consumer))

A pyramid of numbers show the number

of organism at each trophic level

From the base of the pyramid to the top:

1. The size of organism increase/ bigger

2. The number of organism decrease

3. The energy that transfer to next organism decrease

Energy flow in the food web & the pyramid of numbers

1. In the food web, the main source of energy is sunlight.

2. Green plants trap sunlight & convert it to chemical energy (store in food made by photosynthesis)

3. When primary consumer eats the producers (plants), energy is passed to primary consumer, & later will pass to secondary consumer & so on.

4. However, not all energy is passed to the next level because some energy lost as heat.

4.5 Photosynthesis

Photosynthesis The process which green plants make use of sunlight, water, carbon dioxide and chlorophyll to make food in the form of starch and also oxygen.

1. The presence of starch in the plants shows that photosynthesis is occurred.

2. The leaf will turn to dark blue if they contain starch.

3. Factors required in photosynthesis process are:

a) Sunlight

b) Water

c) Carbon dioxide

d) Chlorophyll

Experiment 4: To investigate the factors required for photosynthesis

A. The presence of carbon dioxide

Observation

The leaf in conical flask X turns into dark blue colour but the leaf in conical flask Y does not.

Discussion

Carbon dioxide is available in conical flask X but Carbon dioxide in conical flask Y is absorbed by potassium hydroxide. Without carbon dioxide, the green plant cannot make food, even though chlorophyll, water and sunlight are present.

(Water) (Dry cotton wool) (Cotton wool soaked with limewater) (Leaf receiving all other requirements) (Potassium hydroxide)

B. The presence of sunlight

Observation

The part of leaf which was covered does not turn to dark blue colour but the part of leaf which was exposed to sunlight turns to dark blue colour.

Discussion

Photosynthesis only occurs at the part of leaf that exposed to sunlight.

(Part of the leaf that does not receive sunlight remains brown after starch test) (Dark blue) (Leaf covered with black strip)

C. The presence of chlorophyll

Observation

The parts of the leaf that are coloured yellow do not turn dark blue. But, the part which green in colour turns in to dark blue colour.

Discussion

Only the green part of leaf contains chlorophyll will help to make food through photosynthesis process.

Example:

Avariegated leafis aleafwhich contains green and non green parts. As the green parts contain chlorophyllthey may undergophotosynthesis, but the non green parts do not containchlorophyllso they can notundergo photosynthesis.

Ficus aspera

4. The importance of photosynthesis:

a) Enables the green plants to produce their own food.

b) Supplies food to the animal.

c) Maintain the balance of oxygen & carbon dioxide in the atmosphere.

Carbon Cycle & Oxygen Cycle

Carbon Cycle

The use and release of carbon dioxide is called the carbon cycle.

The process involve in the carbon cycle:

a) Photosynthesis Carbon dioxide use by green plants to make food

b) Respiration Carbon dioxide is released into the air.

c) Decomposition (decaying of dead animal/plant) Carbon dioxide returned to air.

d) Combustion of fuels Carbon dioxide is released into the air.

Oxygen cycles

The continuity use and release of oxygen is called the oxygen cycle.

The process involve in the oxygen cycle:

a) Photosynthesis Oxygen is released into the air.

b) Respiration Oxygen is used by plants and animal to break down the food.

c) Decomposition (decaying of dead animal/plant) Oxygen is used during the process by bacteria

and fungi.

d) Combustion Oxygen is used when things burning.

e) Rusting - Oxygen combines with iron to form rust.

Prepared By: Teacher Ummi Syahira binti Jemsari