UNIT 4 Living Things and Their Environment

Levels of Biodiversity

Biodiversity, a contraction of "biological diversity," generally refers to the variety and variability of life on Earth. One of the most widely used definitions defines it in terms of the variability within species, between species, and between ecosystems. It is a measure of the variety of organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation (number of species) within an area, biome, or planet. Terrestrial biodiversity tends to be greater near the equator which seems to be the result of the warm climate and high primary productivity.

Biodiversity is not distributed evenly on Earth. It is richest in the tropics. Marine biodiversity tends to be highest along coasts in the Western Pacific, where sea surface temperature is highest and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, but will be likely to slow in the future.

07.05.16

Classifying and Naming Organisms

For organisms to be studied and information about them shared to those who need it, scientists grouped them into meaningful classifications. The different groups are ranked from the largest to the smallest groups. Large groups include many organisms with few similarities. Small groups include few organisms having more similarities.

Organisms which have more similarities would then, be closely related than those which have less similarities. These classifications or categories consist of the domain, kingdom, phylum, class, order, family, genus and species. The domain is the largest category into which organisms have been classified. This is followed by the kingdom category subdivided into various phyla (sing. phylum). A phylum consists of different classes, each class with several orders, an order with different families. Families consist of several genera (sing. genus) and each genus comprise the smallest group of various species.

 A species is a group of similar organisms and capable of reproducing their own kind. This means only members of the same species can mate and produce fertile offspring. The dog, waling-waling (an orchid), milkfish (local name, bangus), rice plant and humans like you are examples of a species. With the information available about organisms from the early studies to the present, scientists came up with the three-domain system of classification. Before, organisms were only grouped into eukaryotes and prokaryotes. Remember in your previous year, you knew about the nucleus in cells that contain DNA in chromosomes having a role in heredity.

In eukaryotes, these materials are enclosed in a membrane while in prokaryotes they are not. Most prokaryotes are tiny and unicellular, thus, are referred to as microorganisms. A lot of eukaryotes are multicellular, thus, are larger in size because of the greater number of cells their bodies contain. Recently, prokaryotes have been divided into two domains, namely: Archaea and Bacteria. The eukaryote group was retained and now consists the third domain (Eukarya) that includes protist, fungi, plants and animals. Table 1 shows an example of how organisms are classified.

07/27/16

Archaea Domain: Kingdom Archaebacteria

Archaea are tiny, simple organisms. They were originally discovered in extreme environments (extremophiles), but are now thought to be common to more average conditions. Many can survive at very high (over 80 °C) or very low temperatures, or highly salty, acidic or alkaline water. Some have been found in geysers, black smokers, oil wells, and hot vents in the deep ocean. Recent research has found ammonia-eating archaea in soil and seawater.

In the past they had been classed with bacteria as prokaryotes (or Kingdom Monera) and named archaebacteria, but this classification is a mistake. The Archaea have an independent evolutionary history and show many differences in their biochemistry from other forms of life. They are now classified as a separate domain in the three-domain system. In this system, the three distinct branches of evolutionary descent are the Archaea, Bacteria and Eukaryota.

Archaea are, like bacteria, prokaryotes: single-celled organisms that do not have nuclei and cell organelles of the eukaryote type.

Bacteria Domain: Kingdom Eubacteria

Members of eubacteria are unicellular and microscopic. They are referred to as the true bacteria and are usually called the “bacteria” group. Their cell walls are made of peptidoglycan, a carbohydrate.

Bacteria consist of a diverse group. They vary in shape, size, and function. They can be found in almost all kinds of places, in soil, water and air. Some are present in raw or spoiled food; others live in or on other organisms including your body. You must have known that they also cause disease and harm to other organisms. But most importantly, bacteria have a variety of uses for the environment and for humans.

08/02/16

Protista

Members of Kingdom Protista come from unrelated ancestors. This grouping is referred to by biologists as an artificial grouping. The inclusion of the large number of unicellular organisms under this kingdom is just for convenience. Protists differ in size, movement and method of obtaining energy. Though most of protists are microscopic, some can grow to as high as several meters. In terms of method in obtaining energy, protists are classified into three groups. Phototrophs produce their own food. Heterotrophs feed on other organisms. This group is also divided into a group with no permanent part for movement, those with cilia, and those with limited movement. Others which are nonmotile and form spores belong to the sporozoan group. Members of this group are all parasitic. Phototrophs are like plants in that they have chlorophyll. This group includes the algae, dinoflagellates, and euglenoids.

Algae may be green, golden, brown or red. The chlorophyll in green algae is not masked in contrast to the other members of the group. The carbohydrate that green algae produce is stored as starch. They grow on wet, humid rocks or bark of trees, in non-flowing canals, in seas, freshwater bodies and even polluted waterways. Green algae differ in size and shape. Some are unicellular; others form colonies, sheets, filaments, tubes and ribbons. Some green algae are edible. The marine green alga Caulerpa lentillifera is eaten fresh as salad.

08/24/16

 Fungi

   Fungi are members of the Eukaryota classification. They are either unicellular like yeast or molds, or multi-cellular like mushrooms. Fungi cannot produce their own food due to lack of chlorophyll. Some fungi need hosts to survive while others decompose dead organisms.

   Fungi undergo asexual reproduction by forming buds and spores in large numbers. These spores are abundant in the environment and can be carried by wind, water, and animals. When spores arrive in suitable areas, they develop into a new generation of fungus.

   Fungal bodies consists of hyphae with root-like rhizoids that attach themselves to the fungi while attaching to the substrate which they can grow and absorb nutrients.

08.30.2016

The Plant Kingdom

·         Plants are autotroph, which means they can make their own food. Plants consist of two groups: Vascular and Non Vascular.

o   Non-vascular Plants

§  Liverworts, mosses, and hornworts are non-vascular plants. They attach to the soil surface with root-like rhizoids. These root-like structures absorb water and nutrients from the environment and the surface. Non-vascular plants play an important role in the ecosystem as they provide oxygen to many organisms much like vascular plants.

o   Vascular Plants.

§  From the tallest trees to the prickliest of cacti. Vascular plants use true roots to absorb water and nutrients directly from the soil. These roots are more effective than rhizoids because of the more rigid structure, deep attachment to the dirt, and complex tissue arrangement.

09/06/16

·         Gymnosperms

o   Gymnosperm is any vascular plant that reproduces by means of an exposed seed, or ovule—unlike angiosperms, or flowering plants, whose seeds are enclosed by mature ovaries, or fruits. The seeds of many gymnosperms (literally “naked seeds”) are borne in cones and are not visible until maturity. Taxonomists recognize four distinct divisions of extant (non-extinct) gymnospermous plants—Coniferophyta, Cycadophyta, Ginkgophyta, and Gnetophyta—with 88 genera and more than 1,000 species distributed throughout the world.

·         Angiosperms

o   Angiosperms are seed-bearing vascular plants. Their reproductive structures are flowers in which the ovules are enclosed in an ovary. Angiosperms are found in almost every habitat from forests and grasslands to sea margins and deserts. Angiosperms display a huge variety of life forms including trees, herbs, submerged aquatics, bulbs and epiphytes. The largest plant families are Orchids, and Compositae (daisies) and Legumes (beans).

10/25/16

The Animal Kingdom

 Animals come in different shapes and size; they can be the smallest of ants to the biggest of whales. Each animal also vary in habitat. Some can live in the coldest part of Antarctica and some can swim under the Mariana Trench. Animals are eukaryotes, they are complex and multicellular. Eukaryotic cells have no cell walls unlike bacteria, this makes animals less rigid but unique.

·         Sponges

o   Sponges are animals of the phylum Porifera; meaning "pore bearer"). They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes.

Cnidarians

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•   The name Cnidarian comes from the Greek word "cnidos," which means stinging nettle. Casually touching many cnidarians will make it clear how they got their name when their nematocysts eject barbed threads tipped with poison.

•     Cnidarians are incredibly diverse in form, as evidenced by colonial siphonophores, massive medusae and corals, feathery hydroids, squids, octopi, and box jellies with complex eyes.

•      The flatworm group belongs to Phylum Platyheminthes (in Greek platys means flat, helmins means worm). As their name suggests, they are flat and ribbon like organisms. Flatworms are found in freshwater, in wet places and marine waters. They include the free-living or nonparasitic worms, the parasitic flukes, and the tapeworm group. Planaria is an example of a free-living flatworm. It lives in moist surfaces, under rocks in ponds, rivers and even aquariums. Flukes are parasites that live in other animals including humans.
•      Tapeworms are also parasitic flatworms like flukes without a digestive system. It can have fish, cows and pigs as hosts. Humans can be infected with tapeworms if they eat uncooked fish, beef or pork.

Flatworms

The simplest animals that are bilaterally symmetrical and triploblastic (composed of three fundamental cell layers) are the Platyhelminthes, the flatworms. Flatworms have no body cavity other than the gut (and the smallest free-living forms may even lack that!) and lack an anus; the same pharyngeal opening both takes in food and expels waste. Because of the lack of any other body cavity, in larger flatworms the gut is often very highly branched in order to transport food to all parts of the body. The lack of a cavity also constrains flatworms to be flat; they must respire by diffusion, making a flattened shape necessary.

Roundworms

Roundworms, or nematodes, are parasites that can infect people. They usually live in the intestines. There are different kinds of worms that can cause infection, and they can range in length from 1 millimeter to 1 meter.

Most often, eggs, or larvae, live in the soil and get into the body when you get them on your hands and then touch your mouth. Some can also get into the body through the skin.

Echinoderms

Starfishes, sea cucumbers, and sea urchins are examples of echinoderm. All echinoderms are marine animals. Starfishes live on coral reefs, Sea lilies burrow themselves underground, and some sea cucumbers root themselves on the seabed.

Echinoderms have their most parts inside the center of their bodies. They develop spines made of hard calcium. Under their skin, they have endoskeletons or internal skeletons. Echinoderms have tube feet for consuming food, breathing, and even breathing. They also have the ability to regenerate any part of their body.

Arthropods

Insects, crustaceans, and arachnids have distinctive heads, abdomens, and thorax.

Insects like beetles, grasshoppers, and butterflies have a thick, hard, and flexible exoskeleton. When the insect outgrows their skeleton, they could just remove and grow a new one.

Crustaceans like crabs, shrimps, and lobsters have hard shells to protect themselves; they can travel on both land and water, or being completely a marine animal. Some have claws for attack and defense, and even mandibles for eating.

Arachnids like spiders and scorpions have four pairs of legs; some have a cephalothorax or the fusion of the thorax and the head. Spiders have fangs for predatory purposes and some fangs have deadly venom. Scorpions have venomous stingers attached to their tails and claws for defense and hunting.