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1. To preven extinctions of plants and animal species.


2. Maintain a stable & balance ecosystem. This prevents the disruption of natural cycles such as the water & carbon cycles and prevent global warming.


3. Maintain a large gene pool. Wild plants and animal posses favourable genes in which we can cross-breed to ensure better quality yield.


4. Ensure the conservation of marine life, a source of food for humans.


5. Conservation is of scientific value. The study of wildlife provides useful information to humans. [Learning about evolutions from studying wildlife]


6. Conservation preserves natural scenery and wildlife for us to appreciate. Maintains natural resources for outdoor recreational activities.


7. Maintain the biodiversity. Rainforests, esp Tropical Rainforests house a large number of species of organisms. Many tropical plants serve economic importance as they are sources of raw materials for the different industries.

(a) Rattan is used to make furniture. Rubber from latex of rubber trees are used to make tyres. Fibres from cotton are used to make clothes while fibres from coconut husks are used t make ropes.

(b) Tropical plants provide raw materials for medicinal drugs/natural insecticides. I.e.: Quinine, an anti-malaria drug from the bark of Cinchona, and morphine, a pain-surpressing drug derived from the sap of the poppy plant. Certain poisonous animals may also contain chemicals that have medicinal value.

(c) Provides us with food. Rice, pineapple and bananas are examples developed from rainforest plants.

(looks super disgusting...)

Climate Changes

Desertification also cause climate changes. The water absorbed and retained by the roots of the trees are lost as water vapour during transpiation thus causing rainfall. When the trees are cleared, the area dries up and annual rainfall decreases.

Overfishing

Some fishes have been caught in such large numbers that their population have decreased drastically, just to satisfy the growing population.

Most fishing gears catches marine life indiscrimnately; catching any marine life in its track. Other marine lifes are unintentionally caught during which. These 'accident' catches are then dumped back into the sea but often die:(

Methods of fishing destroy the seabed and marine habitat as well!:(

1. Shrimp/prawn trawlers drag large fishing nets along the seabed. Many unwanted species are trapped in the proccess.
2. Scallop dredges scrape the seabed, destorying the coral reefs and organisims living under teh seabed.
3. In cynaide fishing (cynaide a type of poison), stuns the fish and makes them lose the ability to swim properly. Explosives such as dynamites are used to stun fishes as well. These poisons kill corals and many other marine life.

Effects:

-Some species of fishes will be caught faster than they can be replaced, leading to a drop in their population.

-Marine lives caught unintentionally often die, endangering certain species of animals.

Eutrophication

Chemical fertilisers containing nitrates and phosphates are used to increase the yield of crops but overusing of these fertilisers causes water pollution!!!

Fertilisers not absorbed by the plants may be washed away into nearby rivers/streams. --->

Nitrates and phosphates in the fertilisers similary aid the growth of algae and water plants. The enrichment of nutrients would lead to a profuse growth and increase in number of these organisms in the stream. This is called Eutrophication. --->

Submerged algae and plants die due to the lack of sunlight and the dead bodies are decomposed by bacteria. Bacterial then grow and multiply rapidly, using the oxygen in the water. --->

Other organisms living in that habitat dies due to the lack of oxygen.

Biomagnification

Insectisides are used on plants to kill the insects but they inevitably end up affecting other organisms! DDT (a type of insectiside)is non-biodegradable. They remain in the soil for many years and the insecticides on the plants might we carried by rainwater to water bodies. In high concentrations, they may poison fishes/animal that take in the polluted water/feed on the contaminated fishes.

DDT is insoluble in water ans is stored in the fatty tissues of organisms. It cannot be excreted. Organisms cannot break down DDT. Therefore, DDT accumulates in bodies of the consumers, resluting in the DDT being passed along food chains, increasing in concentrations along each trophic levels. This = Bioamplification.

The top consumers suffer the toxic effects due to bioaccumulation.

1. During photosynthesis, green plants absorb carbon dioxied from the environment and use it to manufacture carbohydrates. i.e.: glucose.
2. Glucose may be changed into other organic compounds such as fats, amino acids and proteins.

3.

• When animals feed on these green plants, the carbon compounds becomes a part of their body.
• Carbon compounds may be preserved in fossil fules such as coal, natural gas and oil.

1. Respiration

When organisms respire, carbon compounds like glucose are broken down in their bodies and carbon dioxide is released into the environment.

2.Combustion

When fossil fuels like coal and natural gas are burnt or undergo combustion, carbon compounds preserved in the fossil fules are broken down and CO2 is released.

3.Decay

When organisms die, their bodies decay or are broken down into simpler substances by decomposers. Carbon dioxide is one of the simple substances released during decay. Some of the simpler substances are absorbed by the decomposers to become a part of their body. When the decomposers respire, carbon compounds are broken down and carbon dioxide is given off. I.e.: Methanobacterium- Utilises acetate and produces methan and carbon dioxide.

1. Ultimate source of energy is the sun.
2. Light energy absorbed by chlorophyll in the plants is converted into chemical energy during photosynthesis.
3. Energy in the producers(PLANTS) is transferred from on trophic level to the next via feeding.
4. Flow of energy through the ecosystem is non-cyclic. Energy is released as heat as in flows through the ecosystem and this energy does not return to the same system or organisms that produced it.
5. Dead organisms, egested and excreted materials contain trapped chemical energy. This energy is released to the enviroment by the activity of decomposers. Decomposers use some of these energy for their own needs (absorb the energy and becomes a part of their body) and the rest is lost to the enviroment as heat energy.

Eventually, all the energy that enters the biotic part of the ecosystem is lost as heat energy.

(i) Ecological pyramids are used to compare the trophic levels in a food chain.

The bottom of the pyramid is Trophic Level 1. The base of the pyramid is more often than not, a producer and mostly the highest in number amongst the other organims and the trophic levels above it. This is so as energy is lost when it is passed from one organism to another. The producers get the chemical energy directly from the sun thus they tend to be the highest in number as the posses the most energy ( as would be seen in an Energy-Pyramid).

In a pyramid of numbers, all the organisms at each trophic level are taken into account, regardless of their size and stage of development.

Tree->Aphids->Ladybirds

The tree is huge and many aphids would feed on that one tree that contains alot of chemical energy and the ladybirds would feed on the many aphids that are feeding on the tree. This pyramid of numbers would be inaccurate because at Trophic Level 1, the quantity should be the greatest.

Variation in Ecological Pyramids; Pyramid of Numbers

A pyramid of numbers may be inverted if:

• Organisms at one trophic level are parasitic on organisms of another trophic level
• Many small organisms of one trophic level feed on a large number of organism of another trophic level.

2. Pyramid of Biomass

A pyramid of biomass aloows us to compare the mass of organisms present in each trophic level at a particular time.

The pyramid of biomass is constructed based on the dry mass of organisms in each trophic level at any one time. This is called the standing mass of organisms.

(i) How do the physical features of the surroundings affect organisms?

(ii) What are theses phyiscal factors?

(iii)Give exmaples of how organisms adapt to these phyiscal factors.

(i) The physical features of the surroundings and the nature of the soil determines the type of plants living in that region. Animals rely on plants directly/indirectly for food, thus, animals living in that region are determined by the plants growing in that region- Organisms found in a region are usually adapted to the physical features of the surroundings.

(ii) Physical Features affecting the surroundings are as follows (6):

1.Light Intesity

2.Temperature

3.Amount Of Water

4.Oxygen Content

5.Salinity

6.pH of Soil/Water

(iii) 1. Light Intensity

Green plants exists in regions with adequate sunlight. However, bright light cause plant stems to grow more slowly. (Plants growing in shades are longer) Therefore, certain plants have developed adaptions to screen off excessive sunlight. Some plants have a dense covering of hair on the leaf epidermis or a thick layer of thick-walled cells [difficult for sunlight to reach insude cells?] called the hypodermis just beneath the epidermis. These adaptions helps the plants to screen off excessive sunlight and reduce the rate of transpiration( Evaporation of water from aerial parts of plants).

2.Temperature

Most organisms cannot stand extremes of temperatures. A temperature too high or too low would kill an organism. Many flowering plants are adapted to changing seasons. Such plants are able to withstand high and dry seasons or though winter by:

1.Storing food underground in storage organs

Water is vital to an organisms's survival. Hence, the availibility of water is a major factor affecting the number of organisms living in a particular region. However, there are some organisms that are adapted to survive under conditions where there is a limited supply of water. For e.g.: Camels are able to survive for many days without water because they can drink more that 100litres of water when available. Some plants, known as xerophytes are adapted to survive prolonged drought, harbouring the following characteristics:

1. They reduce the rate of transpiration by shedding their young leaves( Transpiration is the evaporation of water from aerial parts of the plants)/ developing leaves that are reduced to spines (reducing the surface area in which water can be evaporated from)

2.Stem becomes fleshy from storing up too much water

3.The green stems take over the function of photosynthesis from the leaves

Leaves reduced to spines!

Plants that live in water or very wet places are called Hydrophytes- Fully Submerged, Partially Submerged or Free-floating:)

Mangrove plants, such as Avicennia, have their roots burried in oxygen-poor mud. Special beathing roots called Pneumatophores project above the mud surface. Pneumatophores have pores for gaseous exchange and oxygen enters the openings and passes downwards to the whole root system.

4. Oxygen Content

Most organisms cannot survive in enviroments of low oxygen content. However, some aerobic organisms posses special adaptions that enable them to obtain sufficient oxygen. I.e.:

1)Pneumatophores in mangrove plants.

2) Fishes living in water of low oxygen content are usually air-breathes. They come to the water surface to gulp air.

5. Salinity

/Salt concentration of water is an important factor affecting the aquatic organisms. Animals living in the sea water tend to lose water to sea by osmosis as the seawater contains a > concentration of salt than the cytoplasm of the animal cells! Therefore, salwater/marine fishes have a waterproof coat ( water does not enter/exit) consisting of closely-fitting scales covered by a slimy mucous material( makes it more difficult for water to enter/exit?) , reducing water loss:)

In contrary, the cytoplasm of the cells in the freshwater organisms has a higher salt concentration than the freshwater. Hence, water enters the organisms by osmosis(causing plant cell to become turgid). The cells of freshwater plants have rigid cell wallls that prevent them from bursting. Protozoa such as the Amoeba have contractile vacuoles to remove excess water that enters by osmosis. Most freshwater fishes possess slimy scaly skins which keep water from entering their cells.

Additional Information: Most aquatic organisms are so highly specialised that they can only survive in certain habitats. Many freshwater organisms cannot survive in seawater and vice versa. Hence, starfishes and corals can only be found in the sea. They are not even found in brackish where seawater and freshwater mix. In brackish, the salt content can change considerably.

6.pH

Seawater is alkaline with a pH of about 8. In freshwaters, pH differs from regions to regions is ponds and streams.

okay this is so tormenting!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!