Kinds of Ecosystem

A. Natural Ecosystems

Considering the wide variety of Philippine habitats, the same can be expected of natural ecosystems in the country. However, only three types of natural ecosystems are described below.

1. Forests

Because the Philippines is close to the equator (between 4^o 23’ and 21^o 25’ North Latitude) and surrounded by a vast expanse of ocean, the country receives a high rainfall (around 200 mL per year); it is classified as a tropical rain forest biome.

Original forests are called virgin forests or primary forests. Large forest areas are at times destroyed by careless logging and kaingin farming and, sometimes, by forest fires. As long as seeds of forest trees reach the area and water is available, the destroyed area soon becomes covered with trees again. The new growth is called a second-growth forest or secondary forest.

In the Philippines primary forests in the lowlands include mangrove forests, beach forests, dipterocarp forests and molave forests. In the highlands, primary forests include pine forests ( such as those found in the Mountain Province, the Zambales mountains, and Mindoro mountains) and mossy forests (or tropical upper mountain rain forests).

The richest type of tropical rain forest is the dipterocarp forest. It has the highest number of plant and animal species. The thick canopy is a rich habitat of birds, while the thick layer of decaying leaves beneath the trees is a rich habitat of leeches, millipedes, centipedes, and land snails. Mammals, birds, reptiles and invertebrates abound on the trees, on the ground and in the soil.

Then there are also freshwater swamp forests such as those in Liguasan Marsh and Bulusan Marsh in Cotabato. They have low trees, patches of shrubs, and water grasses. Freshwater swamp forests are a special type of primary forests.

2. Grasslands

Only a few grasslands in the Philippines are natural formations; an example is the one on top of Mt. Pulag in Mountain Province. It rests above the mountain’s tree line. The uppermost 500 meters of Mt. Apo is also covered with rough and rocky grassland. The rest are the result of repeated destruction of forests. Such is the case of the grassland found in Mt. Malindang which resulted from years of logging and slash-and-burn farming. The dominant vegetation is grasslands in the Philippines consists of Cogon and Talahib both of which need abundant sunlight and moderate amount of moisture. Animal life in grasslands commonly includes snakes, lizards, rats, birds, and insects.

3. Coastal Zones

Because the Philippines is made up of 7107 islands, it has a very extensive coastline. Coastal zone refers to the strip of land at the edge of the sea or lake, including both the exposed and submerged portions. Along the coastal zone are mangrove forests, beaches, tidal flats, areas covered with sea grasses and coral reefs are among the richest. For example, the dominant vegetation in mangroves is bakawan; other plants include those locally called nipa, tangal, and busain. On these trees live many kinds of birds, lizards, snails and insects. And in the water beneath the trees, different kinds of fish, shrimps, crabs and mollusks abound.

B. Man-made Ecosystems

As the name implies, these are ecosystems built and maintained by people by people. They include agricultural ecosystems, fishponds, and urban ecosystems.

Examples of agricultural ecosystems are croplands (planted to rice, sugarcane, etc.) and plantations or orchards (planted to banana, coconut, etc.).

In the Philippines, two types of fishponds have proven to be lucrative to the owners but have negative impacts on the natural environment. These are: extensive fishponds converted from coastal mangrove forests and extensive fishpens that practically cover entire lakes, as in the case of Sampaloc Lake and Laguna de Bay, both in Laguna.

Examples of urban ecosystems are parks, greenbelts, subdivisions, and other development projects constructed for human use.

Most students of biology classify ecosystems into natural and man-made ones. Some, however, use the terms controlled (man-made) and uncontrolled (natural) ecosystems. Still others prefer the terms managed (man-made) and unmanaged (natural) ecosystems. However, some ecosystems are both natural and managed; these are natural parks, national parks, wildlife sanctuaries, and others that fall under the so-called National Integrated Protected Area System (NIPAS). These examples are defined by the Department of Environment and Natural Resources as follows:

1. Natural Park is a relatively large area not materially altered by human activity where extractive resource uses are not allowed and maintained to protect outstanding natural and scenic areas of national and international significance for scientific, educational and recreational use. This include Mt. Apo Natural Park, Northern Sierra Madre Natural Park and Mt. Kanlaon Natural Park.

2. National Park refers to a forest reservation essentially of natural wilderness character which has been withdrawn from settlement, occupancy or any form of exploitation except in conformity with approved management plan and set aside as such exclusively to conserve the area or preserve the scenery, the natural and historic objects, wild animals and plants therein, and to provide enjoyment of these features in such areas. Mt. Malindang National Park, Quezon National Park, and Tubataha Reef National Marine Park are some examples.

3. Wildlife sanctuary comprises an area which assures the natural conditions necessary to protect nationally significant species, groups of species, biotic communities or physical features of the environment where these may require specific human manipulation for their perpetuation. Some of the wildlife sanctuaries in the Philippines are Taft Forest Wildlife Sanctuary of Samar and Agusan Marsh in Mindanao. 

FUNGI

 Yeasts, molds, mildews, rusts, mushrooms, and toadstools are among the many different organisms in kingdom Fungi. A Fungus is an organism made of eukaryotic cells with cell walls and that gets its nourishment by absorbing organic substances. Fungi range in size from microscopic, one-celled yeasts to large mushrooms that may be 25cm or more in diameter.

Have you ever seen a mushroom growing in a shady area after a period of warm, damp weather? If so, you will have noticed that mushrooms are like plants in some ways. Mushrooms, like plants, grow upward from the soil. The cells of a mushroom have cell walls, as do the cells of plants. For these and other reasons, biologists once classified mushrooms and other fungi as plants.

Many fungi grow as microscopic tubes, or filaments. These filaments are like those of some kinds of algae and are surrounded by cell walls. However, the cell walls of fungi are different from those of algae and plants. The cell walls of most fungi contain chitin, a substance found in the shells of crabs and the outer coverings of insects.

Unlike plants, fungi have no chlorophyll or chloroplasts. Fungi cannot make their own food. Like animals, fungi use food substances made by other organisms. Fungi also must digest their food. However, fungi do not digest food within their bodies as animals do. Fungi digest food outside their bodies and then absorb the products of digestion. Fungi secrete digestive enzymes into their surroundings. The enzymes break down the organic matter near the fungus into small molecules, which are then absorbed.

You can see that the fungi are organisms with a special mixture of traits. Most biologists now think of fungi as making up a separate kingdom.

The Nature of Fungi

Fungi use organic matter as a source of nourishment. For this reason, fungi generally live close to other life forms or near dead organic material. Fungi need moisture, and many cannot live in strong sunlight. The damp, shady floor of a forest with its covering of dead leaves gives a suitable habitat for fungi. Fungi are often found in forests, but they may be found in many other places as well. Fungi may live inside other organisms. The organisms provide sources of organic matter and the dark, moist conditions in which fungi thrive.

Most fungi are saprobes. Saprobes consume the dead remains and waste products of other organisms. Saprobic fungi break down dead organic matter. They help to put back into the soil minerals needed for the growth of plants.

Some fungi are parasites. Remember that parasites are organisms that get organic nutrients from a living host. A parasite usually harms or injures its host. Fungi may be parasitic on plants, animals, or even other fungi. For example, fungi of the genus Trichophyton are parasitic on humans and cause athlete’s foot. Wheat rust and corn smut are fungi that are plant parasites that harm important food crops.

A third group of fungi are neither saprobes nor parasites. These are fungi that get organic matter from living tissues but that do no harm. Such fungi live closely with other life forms.

General Structure of a Fungus

Most fungi are made up of branching filaments, or tubes, called hyphae. Nuclei are found throughout the cytoplasm. In some fungi the hyphae are divided into cells by cross walls called septa. In other fungi, however, no septa appear. Even in fungi with septa, the cytoplasm is continuous. Each septum has a pore in it.

The hyphae of a fungus grow and branch into a complex, tangled network. Such a network of fungal hyphae is called a mycelium. The mycelium spreads over the surface or into the food source on which the fungus is growing. Often, the mycelium is hidden from view. It may be within the soil or beneath the bark of a decaying tree.

A fungal mycelium spreads in all directions through its food source. The mycelium forms the body of the fungus. When a fungus is mature, part of the mycelium may develop into a structure specialized for reproduction. Look at the bracket fungus growing on the tree trunk in Figure. The mycelium of this fungus has spread throughout the bark of the tree. The part of the fungus that you can see in the photograph is the reproductive structure, or fruiting body. The parts of a fungus other than the fruiting body often called vegetative hyphae or vegetative mycelium.

Most fungi can reproduce both sexually and asexually. Asexual reproduction is often by fragmentation. Fragments of broken hyphae may be carried to new places by wind or water. If conditions are suitable, these fragments will grow into new fungi.

Fungi most often reproduce by producing spores. The air may be so full of fungal spores in late summer that the spores may cause problems for people with allergies. Spores are formed in the fruiting bodies of fungi by either a sexual or an asexual process. In some fungi the fruiting bodies are microscopic. In others, such as mushrooms and bracket fungi, the fruiting bodies can easily be seen with the unaided eye. The method of producing spores and the kind of fruiting body formed are features used to classify fungi.

CLASSIFICATION OF FUNGI

1. Phylum Oomycota

Phylum Oomycota is a large and varied group that includes the water molds, white rusts, and downy mildews. Organisms in phylum Oomycota are called oomycotes. The water molds are water saprobes. The white rusts and downy mildews are parasitic on plants. Other organisms in this phylum live as parasitesin, or on, algal protists, plants, small water organisms, and other fungi.

Most fungi have cell walls made of chitin. Most oomycotes have cell walls containing cellulose, a substance that is found in the cell walls of plants.

Few traits are shared by all oomycotes. One shared trait, however, is the formation of asexual spores called zoospores, each of which has two flagella. The flagella allow the zoospores to swim. Water is needed for asexual reproduction in most oomycotes. Rainwater, the water in soil, or even dew is enough water for the zoospores to swim in.

Sexual reproduction also takes place among the oomycotes. The fertilized egg of an oomycote develops into an oospore. Saprolegnia, a common freshwater mold, can often be seen as a fuzzy, whitish growth on organisms that have died. This water mold usually lives as a saprobe, but it may be a parasite on injured fish and on fish eggs.

The life cycle of Saprolegnia  - asexual reproduction is by means of diploid zoospores that have flagella. These zoospores are produced by mitosis within a spore case called a sporangium. When the sporangium is ripe, it opens and lets out the zoospores into the water. After a few hours, the zoospores become enclosed within walls to become resting spores, or cysts. The cysts later change into zoospores again.

2. Phylum Zygomycota

Phylum Zygomaycota is made up of land-dwelling fungi often called molds and blights. Members of phylum Zygomycota are called zygomycotes. Most zygomaycotes are saprobes. However, some are parasites on plants, animals, or other fungi. All zygomycotes reproduce sexually by means of thick-walled diploid spores called zygospores.

Rhizopus stolonifera is a zygomycote mold that often grows on bread and starchy fruits. It is whitish when young; it is black when it reaches maturity and forms spores. The hyphae that are parallel to the fungu’s growth medium are called stolons. The many smaller, branching hyphae growing downward from the stolons are called rhizoids. The rhizoids go into the food source the fungus is growing on ang give out enzymes that digest the food.

Rhizopus reproduces asexually by forming stalklike hyphae called sporangiophores. These structures stick up into the air from the stolons. At the top of each sporangiophore is a sporangium that has a very large number of asexual, monoploid spores. Note that phore means “carrier” and that the sporangiophore carries the spore case, or sporangium. The spores of zygomycotes, unlike those of oomycotes, have no glagella. When the spores are ripe, the sporangia burst and release the spores. These spores can then germinate into new vegetative hyphae.

Rhizopus also can reproduce sexually through the mating of hyphae of genetically different strains. Stolons from the two strains of Rhizopus grow next to each other. A swelling from each stolon grows toward the other. The two swellings meet and nuclei from each side come together and join so that a diploid cell is formed. This diploid cell forms a thick wall and becomes a zygospore.

Meiosis takes place during the germination of Rhizopus zygospore. The germinating zygospore froms a single sporangium having monoploid spores. These spores appear to be the same as those formed in asexual reproduction. When these spores are released, they grow into vegetative hyphae. They may later reproduce either sexually or asexually.

3. Phylum Ascomycota

Phylum Ascomycota is the largest group of fungi, with about 2000 genera. Members of phylum Ascomycota are called ascomycetes. The yeasts, the powdery mildews, the cup fungi, truffles, and morels are part of this phylum. Also included are a number of molds that cause food to spoil. Most ascomycetes are saprobes, living on dead plant material. However, other fungi are very destructive plant parasites. Some cause diseases such as Dutch elm disease, chestnut blight, and peach leaf curl. Most ascomycetes are adapted to land habitats.

Ascomycotes are sometimes called sac fungi because spores develop in a sac called an ascus. These monoploid, non-moving spores are called ascospores. The ascospores are formed by sexual reproduction followed by meiosis.

The pink bread mold Neurospora crassa is an ascomycote that has been used in ecperiments in genetics and biochemistry

Neurospora and many other ascomycetes reproduce asexually by forming spores called conidia. The conidia are formed on specialized hyphae called conidiophores. After the spores fall from the conidiophores, they germinate to form new vegetative hyphae.

Sexual reproduction in Neurospora begins with the mating of hyphae of different types. The ascogonia are female reproductive structures. They form tubes that fuse with antheridia on the male hyphae. Male nuclei from the antheridia cross through the tubes into the ascogonia. One male nucleus and one female nucleus become isolated in an extension of each ascogonium. The male and female nuclei join to form a zygote. The zygote goes first through meiosis and then mitosis to produce eight monoploid cells inside an ascus. The eight cells form thick walls as they ripen into ascospores. Hyphae grow around the developing asci to form a fruiting body called an ascocarp. Each ascospore is able to develop into fungal hyphae.

Yeasts, one-celled ascomycetes of the genus Saccharomyces, are used in baking and brewing. Saccharomyces means”sugar-fungus”. These fungi live on sugary food sources, such as grape juice.

Saccharomyces yeasts reproduce asexually by budding. Budding is a method of reproduction that involves an outgrowth, called a bud, from the cell. The nucleus finally divides and one of the new nuclei moves into the bud. The bud later breaks off, becoming a separate yeast cell.

Saccharomyces yeasts can also reproduce sexually by forming ascospores. In such cases the yeast cell becomes an ascus. Such an ascus may contain four or eight ascospores.

A number of common molds of the genera Penicillium and Aspergillus have no known sexual reproduction. These molds have been classified in phylum Ascomycota because they form conidiophores and reproduce asexually by means of conidia. Penicillium molds often are seen as bluish-green growths on oranges and other citrus fruits and sometimes on bread.

4. Phylum Basidiomycota

Phylum Basidiomycota includes some of the largest fungi, such a mushrooms, puffballs, and bracket fungi. Puffballs are similar to mushrooms, but the cap is roundish. Bracket fungi look like shelves growing on trees. Members of phylum Basidiomycota are called basidiomycetes.

Basidiomycetes produce spores in club-shaped structures called basidia. The monoploid spores, called basidiospores, are formed by meiosis of a zygote formed by sexual reproduction. In most basidiomycetes the structure that bears the basidia is called a basidiocarp. Because of the shape of the basidia, members of this phylum are called club fungi.

The object often called a mushroom is only a small part of the complete fungus. Most of a mushroom fungus is made of an underground mycelium. The mycelium absorbs nutrients from organic matter in the soil. The part of the mushroom seen above the ground is the basidiocarp, or fruiting body.

Mushroom do not form asexual spores. The basidiospores, or sexual spores, of mushrooms change into hyphae that develop into underground mycelia.

The young basidiocarps of some mushrooms look like little rounded balls. A sheetlike veil holds the developing mushroom together. Inside the veil may be another shetlike tissue, the annulus, which draws the edge of the mushroom cap toward the stem, or stipe. When the basidiocarp grows a bit larger, the veil and annulus tear. This tearing allows the mushroom to open like an umbrella. The cap of the mature mushroom has gills on its undersurface. The gills of a mushroom are where the basidiospores are formed.

Club-shaped basidia develop from the surface of each gill of the mushroom cap. Within each basidium, two nuclei join to form a zygote nucleus. The zygote nucleus then undergoes meiosis, forming four monoploid nuclei within the basidium. These four nuclei then travel into projections at the outer part of the basidium. The nuclei develop into four monoploid basidiospores. The basidiospores are released from the basidiocarp when they are mature.

Rusts and smuts are basidiomycetes that do not form basidiocarps. They are small and nearly always parasitic on plants. Many rusts have complex life cycles, infecting different hosts at different stages of the life cycle. Unlike mushrooms, many of these basidiomycetes produce asexual spores as well as basidiospores.

Wheat rust, Puccinia graminis, infects wheat and barberry plants. Basiodiospores develop on the infected wheat plant and are carried by wind to barberry plants. Asexual spores develop from hyphae on barberry plants. These spores are carried by wind to wheat plants.

NUTRITION OF FUNGI

A fungus is in direct contact with its food. The fungus secretes enzymes into the food. These enzymes break large food molecules into molecules that are small enough to be absorbed by the hyphae. Different enzymes act on different kinds of nutrients.

After food has been absorbed, it travels to all parts of the fungus. Think about a mushroom, a saprobic fungus. The underground mycelium of the mushroom is in contact with organic matter in the soil. Above the ground the fruiting body, or basidiocarp has no direct source of food. Food travels from the underground mycelium to the mushroom through the hyphae. Remember that some fungi lack septa in their hyphae. Thus cytoplasm is free to move back and forth through the hyphae, carrying food with it. Even in those fungi with hyphae that have septa, pores in the septa allow the cytoplasm to flow.

Although most saprobic fungi live in the soil, some live in other environments. Bracket fungi are found on both living and dead trees. Those bracket fungi that grow on living trees are believed to be saprobes rather than parasites. They usually consume only dead cells in the bark or in the dead heartwood of the tree.

Parasitic fungi obtain nutrients directly from the living cells and tissues of their hosts. Parasitic fungi often form special hyphae called haustoria. These hyphae are highly branched and specialized for absorbing nutrients. Haustoria pass into the tissues and often even enter the cells of the host.

A few filamentous fungi are predators on such small organisms as protozoans, rotifers, and roundworms. These fungi have special sticky pads or loops that trap the prey. Some types of soil-dwelling fungi form rings along the hyphae. After trapping a worm, the fungus forms haustoria, which pass into the prey. Digestion of the host’s tissues takes place, followed by absorption of the nutrients.

FUNGI AS SYMBIONTS

A close relationship between two species in which at least one species benefits is called symbiosis. A symbiotic relationship in which one organism lives on or in another and harms it is called parasitism. If both species are helped by symbiosis, the relationship is called mutualism. Some fungi are mutualistic.

A lichen is a symbiotic association between a fungus and a blue-green bacterium, an algal protist, or a green alga. The fungus may give structural support and supply certain nutrients for the partner. The bacterium, protist, or plant – unlike the fungus – is able to make its own food. It provides food for the fungus. Lichens live in many habitats, from tropical heat to arctic cold, from deserts to rain forests.

The photosynthetic species found in lichens include about 8 species of blue-green bacteria, 20 species of green algae, and 1 algal protist. The blue-green bacterium Nostoc and the green alga Trebouxia are the most common. All of the photosynthetic species can probably live without the fungi. But the fungi usually need a partner for survival. Lichens that contain Nostoc can use nitrogen from the air as a nutrient.

A mycorrhiza is a structure formed by the mutualistic association of a fungus and the roots of a plant. The fungus grows on the roots, with some hyphae reaching into the tissues of the host plant. Some plants, including elm, maple, and willow, can grow well with or without fungi. Other plants, such as some species of pine, spruce, and oak, need a growth of fungi on their roots. The fungus receives sugars from the roots of the host plant and gives growth-stimulating chemicals to the plant. The fungus also aids the plant in taking in water and minerals.

Orchids have a very close relationship with their mycorrhizal fungi. The fungus invades the cells of the orchid roots and provides organic nutrients to the orchid. Some orchids are too dependent on the fungus that they can live without chlorophyll. Most of the organic matter flows from fungus to orchid. But the fungus may be helped by receiving some amino acids and vitamins from the orchid.

Symbiotic relationships between insects and fungi are fairly common. Many insects have yeasts, along with bacteria, in their digestive tracts. The fungi aid the insect in digesting its food and are helped by receiving a share of that food.

Some kinds of burrowing beetles, termites, and ants keep fungal gardens. The insects bring food to the growing fungi. The fungi serve as food for the insects. Several species of ants of the southern and southwestern United States show such relationships with fungi.

Fungi are common parasites of insects. Sometimes the fungus helps to keep the insect population under control. The citrus mealybug in Florida is controlled by the fungus Entomophtora fumosa, which grows well in California, which has a cool, rainy season.

IMPORTANCE OF FUNGI

A great amount of dead organic material is deposited on the earth’s surface each year. If it were not for saprobes, including many fungi, this waste would build up to massive proportions. The buildup of such wastes would exclude most plants and animals from their natural habitats. Saprobes remove this material by breaking it down. They also return inorganic nutrients and minerals to the soil, where these materials can be used for more plant growth.

Saprobic fungi are able to break down organic material. In some cases this ability causes problems. Mildews and molds form quickly in moist environments. Clothing and other cloth products, such as tents, are often attacked by molds and mildew. Cotton is very often attacked because it is made of plant cellulose. Many molds can break down cellulose. These fungi often cause musty odors, stains, and weakened fabric. Wool, which is a protein fiber, is less likely to be attacked by fungi. There are fewer fungi that can digest protein.

Many foods are attacked by molds. You have probably seen moldy fruits, vegetables, and bread. The downy or cottony molds Penicillium and Rhizopus grow quickly on foods that are in even moderately humid environments. Many of these fungi affect the smell, taste, and appearance of the products they grow on.

Some fungi that attack foods produce poisons that may cause illness in people and livestock. Corn that becomes infected with certain species of Penicillium and Aspergillus may cause poisoning of pigs and cattle. Horses and other livestock may be poisoned by moldy hay. Death may take place because of the effects of the poison on the nervous and circulatory systems.

Ergotism is a disease caused by an ascomycote that is a parasite on rye. The developing ascopores invade the seeds and replace the seed material with hardened, purple-black masses of fungal hyphae. The fungus forms several poisons. People who eat the contaminated grain may have convulsions and other mental disorders.

Although some fungi destroy useful products, many valuable products are made as a result of fungal activity. These include bread, alcohol, cheese, drugs, and enzymes. Fermentation of sugar by yeast (usually Saccharomyces cerevisiae) forms carbon dioxide and ethyl alcohol. The carbon dioxide causes bread dough to rise. Brewers and winemakers use the ethyl alcohol to make beer and wine.

Cheese is formed from milk that has been coagulated to form semisolid curds and a watery liquid called whey. The curds are the newly-formed cheese, sometimes sold as cottage cheese. The curds are ripened, either by bacteria or fungi, to make other kinds of cheese. Most soft cheeses are ripened by fungi. Camembert cheese is soft but has a stiff rind containing the white mold Penicillium camemberti. This fungus gives off an enzyme that makes the cheese soft and buttery and mild in flavor. Roquefort cheese is made from sheep’s milk. The curds are broken up, drained until fairly dry, and inoculated with Penicillium roqueforti, which grows over the curds.

Other important substances are produced by fungi. Antibiotics, including penicillin, are formed by Penicillium. The drug ephedrine used in treating hay fever and asthma, and the B-vitamins are commercially made by yeasts. Some enzymes and organic acids, including citric acid, are also made using fungi.

Some fungi, such as mushrooms, have been thought of as delicacies since the time of the ancient Greeks and Romans. In North America, mushrooms are grown commercially in large mushroom farms. The commercial mushroom is an excellent source of vitamins and the minerals phosphorus and iron. These mushrooms also contain some proteins. Mushrooms are grown in trays of a mixture of straw and fertilizer. The trays are kept in a moist, dark environment which prevents the growth of soil algae and weeds. The fungal mycelium grows throughout the mixture, and the edible basidiocarps rise up above the surface.

There are many species of wild mushrooms that are edible, but some are deadly poisonous. It is difficult to tell nonpoisonous and poisonous varieties apart. Usually the killer mushroom is a species of Amanita, the “death angel.” Even one cubic centimeter of this mushroom can cause death. Since only an expert can identify wild mushrooms, you should never collect and eat wild mushrooms.

Biotic Components of an Ecosystem

Biotic components refer to the different kinds of organism that interact with the environment. There are many ways of grouping these organisms. One way is discussed in connection with the ecological niches in a biotic community: producers, consumers and decomposers.

Another way of grouping organisms is to distinguish between those that can make their own food (the autotrophs) and those that cannot (the heterotrophs). Those that manufacture food  are said to be autotrophic. The terms autotroph and autotrophic came from the Greek words auto (meaning self) and tropikos (meaning nursing or feeding); thus they mean self-nourishing or self-feeding. Autotrophs are the producers of biotic communities.

Most autotrophic organisms manufacture food by utilizing the energy from the sun. The process is known as photosynthesis. Plants, algae and some bacteria have the green pigment called chlorophyll that captures sunlight and thus permits them to perform photosynthesis.

Another group of bacteria has the ability to manufacture food using the energy stored in inorganic molecules. The process is known as chemosynthesis. Compared to photosynthetic autotrophs, chemosynthetic autotrophs have a much more limited distribution in the biosphere. However, they play a very important role in certain habitats such as the deep ocean floor around hydrothermal vents. In such a hot mineral-rich environment, chemosynthetic sulfur bacteria are the sole producers of entire communities of heat-tolerant organisms. The very productive communities thrive near the vents at temperatures of around 40^oC.

The terms heterotroph and heterotrophic came from the Greek words heteros (meaning other) and tropikos (nursing). Heterotrophs are the consumers and decomposers of biotic communities. They may be grouped into two, based on size: The large ones called macroconsumers (the prefix macro-literally means large), while the tiny ones are called microconsumers (micro – means small). Cow, dog and frog are examples of macroconsumers. Microbes such as the malarial parasite, paramecium and nonautotrophic bacteria are examples of microconsumers.

Heterotrophs may also be grouped into four, based on what they feed on: Those that feed on plants (such as carabaos and goats) are called plant-eaters, or herbivores. Those that feed on flesh or meat (such as dogs and cats) are called flesh-eaters, or carnivores. Those that feed on both plants and meat (such as chickens and humans) are called variety-eaters, or omnivores.

Those that feed on small pieces of leaves and other organic matter (collectively called detritus) are known as detritus-feeders, or detritivores. Detritivores are abundant on the forest floor, in soil and in bodies of water.

Still another group of heterotrophs consists of those that absorb dissolved organic materials, usually the product of decomposition. These are called saprotrophs; their mode of feeding is known as saprotrophic nutrition. The most abundant saprotrophs are the saprotrophic bacteria; other examples are mushrooms and other fungi.

Abiotic Components of an Ecosystem

First, try to explain the following observations:

a. Talahib grows well in abundant sunlight, while ferns grow well in the shade.

b. Pine trees grow well in cold countries and, in the Philippines, at high elevations. On the other hand, banana plants thrive in tropical countries.

c. The gabi plant grows well in water-soaked ground, while the rose plant prefers moderate water only.

d. Bamboo can tolerate strong winds, while the banana plant cannot

Certain aspects of the physical environment determine the distribution of plants and animals on land. Three of these are discussed below:

1) climate                  2) soil and                 3) surface relief, or topography

The contrasting behaviors or characteristics of plants cited at the start of this section illustrate the effect of climatic conditions. Identify which of the following climatic elements explains each of the observations: 1. Light          2. Moisture               3. Temperature and             4. Wind

Second, study the following situations:

a. Crop yield in kaingin becomes less and less after two years of continuous planting of the same crop, usually corn or rice. Nutrient loss in this case is rather fast.

b. After continuous application of fertilizer, the productivity of a farm drops because the soil has become acidic. The farmer either applies lime or burns the agricultural wastes on the farm itself to correct the acidity of the soil.

c. Most crops grow better in loam, which generally has higher moisture content than other types of soil.

The principal soil types are sand, loam and clay. They differ, not only in the kind of substances they contain, but also in the size of the soil particles which determines the amount of water the soil can hold as well as the amount of water with dissolved minerals that leaches out of the soil.

The three situations cited above illustrate the effect of soil on plant growth. Specially the soil features are 1) nutrients in the soil,             2. acidity of the soil             3. Moisture content of the soil

The size of the soil particles is important because it affects both the moisture content and nutrient content of the soil. Soil moisture is lost fastest from sand and slowest from clay, either through evaporation or through leaching. Water that percolates through the soil dissolves some minerals from the soil. Incidentally, more acidic soils lose more minerals through leaching than less acidic soils.

Third, consider the following observations:

a. Certain plants and animals are found only in high elevations. For example, cloud rats (Phloeomys and Crateromys to scientists) live only in high mountains such as those in Central Northern Luzon, Southern Luzon, and Mindanao, whereas Rabor’s Giant Mountain Rat (Rattus rabori) is found only in the highlands of Mt. Malindang in Zamboanga Peninsula.

b. Cogon and Talahib are two plants that grow abundantly in Philippine grasslands. But they do not necessarily have the same distribution. Talahib, which prefers more moisture, is found in lowlands and along gentle slopes. Cogon, which tolerates less moisture, can grow along steeper slopes.

c. In the Philippines, the sun is almost always directly overhead at noon. But in high altitudes, the orientation of mountains may be such that one side receives more sunlight than the other side. As a result, the mountain slope that faces the sun generally has thicker plant growth than the other side.

These observations illustrate the effect of topography – particularly 1) altitude or elevation,       2) angle of slope, and   3) orientation of the slope – on plant and animal life.

RUBRIC FOR BIOGRAPHY

Criteria	4	3	2	1
Accuracy of Content	The student shows deep understanding of the life, works, and achievements of the different scientists; how their life and works influence our daily life and the world were discussed in details.	The student shows considerable understanding of the life, works, and achievements of the different scientists; how their life and works influence our daily life and the world were discussed in part.	The student shows shallow understanding of the life, works, and achievements of the different scientists; how their life and works influence our daily life and the world were mentioned but not discussed	The student shows limited understanding of the life, works, and achievements of the different scientists; how their life and works influence our daily life and the world were not discussed.
Organization of Ideas	All elements in the product are logically presented and consistent. A very clear message is conveyed to the audience.	Most elements in the product are logically presented and consistent. A clear message is conveyed to the audience.	Some elements in the product are logically presented and consistent. The message conveyed to the audience is clear but lacks details.	Few elements in the product are logically presented and consistent. The message conveyed to the audience is not clear.
Language	Appropriate descriptive language was used; a variety of strong words creates vivid pictures in the student’s mind.	Appropriate descriptive language was used; some words create pictures in the student’s mind.	Descriptive language was used; a few words create pictures in the student’s mind.	Inappropriate descriptive language was used; some words are too confusing.
Creativity	The product is very creative; a lot of effort and detail went into the work.	The product is creative; some effort and detail went into the work.	The product is somewhat creative; limited effort and detail went into the work.	The product is somehow creative; very little effort and detail went into the work.

ALI BABA AND THE FORTY THIEVES (book review)

THE STORY:

Once upon a time, in a small town in Persia, there lived a poor, cheerful, and well-liked woodcutter whose name was Ali Baba. Unlike his brother Cassim, who married a rich wife and enjoyed an easy life, Ali Baba had to work hard to earn his living to support himself and his family.

One day, while cutting wood from trees near a certain mountain, he heard the sound of many horses coming his way. He figured it must be a fierce band of thieves, so frequent in those days, that he quickly hid his donkey and climbed on top of a tree.

To his expectation they were indeed thieves and they stopped just right in front of the tree where Ali Baba was hiding found next to the side of a huge mountain. They carried with them many loots which they placed in their saddlebags. Just then their leader came and dismounted from his horse. He looked everywhere around first then strode over to a rock. Then raising both his arms, he shouted “Open Sesame!” The wall of the rock split open right before the eyes of Ali Baba. The robbers went in with their horse and saddlebags. When the last man entered the door  just shut itself again. Ali Baba was wise enough to stay put where he was for after some time, the door opened again when upon the Leader shouted “Open Sesame” from inside the cave. Each of the thieves came out and as they did Ali Baba counted them to be forty in all including the leader who was the last man to walk out. Seconds later, the leader again raised his hands into the air and shouted, “Close Sesame!” that sealed off the entrance once more. He climbed up his steed then altogether they rode away.

When they had gone, Ali Baba jumped down from the tree to examine the rock and found out it was solid as it looked. Then, imitating the leader, he raised both his hands into the air and shouted “Open Sesame!” and the door rumbled open. Ali Baba stepped inside. It was dark though he could see treasures glowing in the dark. It downed upon him that he had discovered the secret hiding place of the forty thieves. Quickly, he rushed out to empty the baskets on the donkey’s back and half-filled them with the treasures and covered them with wood so no one would notice when he brings them home. In the same manner as the leader did, he ordered the cave closed shouting, “Close  Sesame!” He hurried home to share the good fortune with his wife.

Ali Baba returned several times to the cave whenever it was safe and convenient. Soon he became rich that his brother Cassim became jealous of him. Once he followed Ali Baba to the cave to learn its secrets. When Ali Baba had left, he tried it himself and it worked well that he was able to get inside. Then he commanded the door to shut close. He became so excited he overfilled the bags that he forgot the magic words and was trapped inside the cave the whole night. When the thieves came back the next morning they saw Cassim and were so annoyed they killed him on the spot.

To make certain no one else knew, the Leader of the Thieves had Cassim’s body cut up into four parts and placed outside the rock. He figured that if anyone would dare pick up the body, then somebody else also knew.

The next day, when the forty thieves were away, Ali Baba came. When he discovered the remains of his brother he took them to Cassim’s wife. For safety, he summoned the slave girl, Morgiana to find someone trustworthy enough to sew Cassim’s body together so he would be buried with everyone thinking he died a natural death.

Morgiana sought the help of an old shoemaker, Baba Mustapha, but blindfolded him to Cassim’s house to sew the body of Cassim together for a gold piece as was the deal.

The captain of the thieves figured right when on their return they could not find the body of Cassim that clearly indicated somebody else knew about the cave. But he must remain careful for any killing must be as discreet as possible lest it arouse suspicions and their very secret becomes known to the world. But as he didn’t hear any gossip in the next few days about unusual deaths, he figured someone must have sewn up Cassim’s body. So he went to town alone and quietly inquired from the tailors, dressmakers and shoemakers, until he came upon the old Baba Mustapha. At first the old man wouldn’t talk but upon being offered two gold pieces he loosened his tongue. He had himself blindfolded again and remembering the steps he took finally located the house. The captain paid off Baba Mustapha, then when alone he marked Cassim’s door with a large cross then crept away to fetch his men.

Morgiana was on her way home then just as the captain left. She was surprised to see the cross on the door, and thinking somebody was up to something, she also marked several other doors in the street the same way that had the captain confused when he returned afterwards with his men. His plans foiled, the captain was very furious and swore he would never rest until he found out who he was.

Determined, the captain engaged Baba Mustafa once again this time for four gold coins. This time he tried to remember the front of the house. He went to his tribe and told them of his plan of how to capture the mysterious thief. He was to disguise himself as an oil merchant while they were to hide themselves inside empty oil jars slung over the backs of donkeys. As a precaution, he left one jar filled with oil just in case. His plan worked as he was well-received by Ali Baba to allow him to lodge for the night. Unfortunately, Ali Baba did not recognize the captain in his new disguise.

The evening, the captain slipped his way quietly to the courtyard where the donkeys were tied.  Then he lifted the jars to the ground leaving word each of his men that he would tap on his jar when the time came.

Incidentally, Morgiana run out of oil to prepare for next day’s meals and thought of fetching some oil in the meantime from the oil jars the merchant had brought in, then have his master pay tomorrow. Just as the captain slipped back to his room, Morgiana came out to the courtyard. She tapped the first jar to see if there was oil, instead he heard someone speak. “Ready, Master?” She didn’t answer but just went on to check on the other jars with the same result. Finally she got to the real jar of oil and took some back to the kitchen. Quickly, she boiled them and poured as much of the still boiling oil into the jars then hid herself. Moments later, it became too warm for the thieves that each of them leaped out of their jars and fled. The captain was furious when later he went back to the court-yard to find all his men have left him. Meanwhile, Morgiana kept all these things to herself for she was not clear what was really happening. But she remembered well the face of the captain though he had left and went his way.

But the captain was not ready to give up. One day, he befriended a young man who turned out to be Ali Baba’s son. Their acquaintance grew until his son invited the captain to their home one evening to meet with Ali Baba, who still did not recognize him as the captain. Meanwhile, Morgiana had just returned and saw through the captain’s disguise and was certain he had come to murder her masters for he kept reaching for his dagger he tucked behind his back as if waiting for the moment when they are both drunk to attack.

She disguised herself as a dancer and slipped a silver dagger into her wide belt. Then she motioned to the musicians Ali Baba’s son has hired to entertain his visitor to play a song. Then slowly she danced and inched her way to the captain. Suddenly the music played faster and faster, she whirled around the room and was throwing up her veils into the air as she got on top of the captain, then without the captain realizing it, she drew out the silver dagger and plunged it right into the chest of the captain.

She explained later that the merchant was the oil merchant and the same man who marked the doors with the view of harming them. Then Ali Baba realize that he was the captain of the thieves. Ali Baba could not thank Morgiana enough and offered her anything for saving his life thrice in a row.

Morgiana asked nothing but prayed Ali Baba would give him her freedom. Ali Baba freed her from the bond of slavery. Now a free woman, she and Ali Baba’s son, who have been in love, were now allowed to be married. And a happy wedding there was. Together as one family, they lived for many, many years in comfort and luxury.

SETTING:

In a small town in Persia.

CHARACTERIZATION:

Ali Baba, a protagonist and victor, a poor wood cutter who discovered the secret words of the cave where the forty thieves hid their treasures that made him rich.

Cassim, lazy but lucky to have married a rich wife, envious of Ali Baba’s sudden fortune he followed him to the cave to learn the secret words, greedy he forgot the magic words on the way out and got trapped and caught by the thieves and mutilated, whose remains were recovered and sewed back secretly by Ali Baba to provide him a proper funeral.

The Leader of the Forty Thieves, greedy and revengeful, swore to claim his wealth back from Ali Baba but failed at all occasions until he was killed by Morgiana.

Morgiana, wise and faithful slave of Cassim’s wife, who helped find the shoemaker to sew up his master’s body, a heroine who thwarted all the plans of the Leader of the Thieves until she finally got rid of him for good.

Baba Mustapha, blind old shoemaker hired by Ali Baba thru Morgiana to sew up the body of Cassim and keep