The Kingdom Protoctista

This kingdom contains all single celled organisms in which there is a distinct nucleus enclosed in a membrane, and in which there are also other discrete organelles, such as mitochondria and endoplasmic reticula. It includes all those microscopic organisms, such as amoeba and paramecium that were once regarded as single celled animals and placed in the phylum Protozoa. It also includes the slime moulds. The large sea weeds that is also included in the Protoctista because, although they are multi cellular organisms, their cells are all alike and not easily differentiable from single celled algae.

The sea weeds include species with fronds many meters long and made up of millions of cells, but they are included with the single celled organisms in the Protoctita because their cells are all more or less alike. Some biologists regard the seaweeds as assemblages of cells rather than true multi cellular organisms. There are three major groups or phyla- the green sea weeds (Chlorophyta), the brown sea weeds (phaeophyta) and the red sea weeds (Rhodophyta). All contains chlorophyll and make their food by photosynthesis, but the brown and red seaweeds contain other pigments that mask the chlorophyll. They have a variety of reproductive strategies.

The Five Kingdom of Life and The Characteristics Of Living Things

Until fair recently, all living things were classified as either plants or animals this simple division is perfectly adequate for non scientific purposes, but most biologists now recognize five separate kingdoms of life, based largely on microscopic structure and bio chemical activity, these are the bacterial kingdom, or Prokaryote; the Protoctista; the Fungal kingdom; the Plant kingdom and the Animal kingdom.

Although we cannot give a simple definition of life, there are seven distinctive features that are shared by all living things and distinguish them from inanimate objects.

These characteristics are:

Movement

Excretion

Respiration

Reproduction

Irritability

Nutrition

Growth

The initial letters of these features form the word MERRING, a convenient mnemonic for keeping them in mind.

The Kingdom of Prokaryote:

This kingdom contains the bacteria. These are all microscopic, single celled organisms, but their structure is very different from that of other single celled organisms, with no obvious nuclei or other well defined structures – organelles- within the cell division, sometimes as often as once every 15 minutes. Some bacteria can carry out photosynthesis, using the energy of sunlight just as plants do, but most of them rely on other chemical reactions to provide their energy. Bacteria play a major role in the natural world, where they are heavily involved in the breakdown of dead plants and animals and return back to the soil.

Origin of Life

The earliest traces of the life on earth have been found in the rocks about 3.5 billion years old. They are layered structures similar to those formed by some of today’s marine bacteria, and it is generally accepted that the first forms of life were some kind of bacteria. We do not know exactly how these first living things or organisms were produced, and probably never will, but laboratory experiments suggest that energy from lightning or from ultra violet radiation could have caused gases, like methane and ammonia to combine with simple minerals to produce proteins and other building blocks of life such reactions would probably have taken place in shallow water.

As more and more life’s building blocks were formed, they inevitably mingled and reacted with each other to form new compounds. Eventually, a chance combination gave rise to a molecule of DNA, a self replicating material that is the basis of all living matter. Here, perhaps, was the “spark of life” and the scene was then set for the appearance of the first cells and the subsequent evolution of all life on Earth. Since the beginning of life, millions of different kinds of organisms have come and gone. It is estimated that there are about 300,000 different kinds of plants in the world at the present time, and there may be over five million kinds of animals- or some estimates, nearer ten million – although only a little over a million of these have so far been described.

Map Projections

Representing a globe on a flat plane requires the use of projections. Cylindrical projections are created by wrapping a piece of paper around the equator to form a cylinder. This was the principle used by the Flemish geographer Geradus Mercator to draw up one of the first reasonably accurate maps of the world in 1569. A Mercator projection shows equatorial regions very accurately and has the advantage that the shape of the landmasses o the map are the same as on the ground, which is useful for navigators. However, away from the equator, the actual areas of the landmasses become more and more distorted so that Greenland seems bigger than Africa. Mercator’s projection is most distorted at the poles because the point of each pole is stretched out into a line as long as the equator.

Arno Peter, a German historian, devised an alternative in 1973. Peter’s projection is also cylindrical but it differs in that the north south scale is adjusted so that the actual areas of the landmasses are accurately represented at all latitudes, although Peters’ projections shows the correct areas of all landmasses, it distorts their shapes. For example Africa appears to have been stretched while Greenland seems squashed.

Another form projection is the Zenithal or Azimuthal projection. The paper remains flat and touches the globe at the north or South Pole. Lines of longitude show their correct angles. For this reason they are often used to represent polar region.

A conical projection , in which the paper is rolled into come and placed over the globe to touch it along the line of latitude, shows countries with the minimum of distortion.

Google’s projection is not strictly a projection but a series of manipulations of the curved surface of the sphere. Such maps look rather like the skin of an orange after it has been removed in one piece and rolled out flat. The continents are shown accurately but the oceans are opened up to stretch the segments on to the paper.

Mapping Symbols

          A large scale map can show a relatively high level of detail, whereas a small scale map contains more information in relation to its size. The scale of a map is expressed as the ratio between the size of the map and the size of the corresponding area on the ground. This can be expressed as a simple ratio, for example 1:100, where one unit on a map is equal to 100 of the same units on the ground.  Alternatively, the ratio may be expressed using different units, for example 1cm: 1km, in which one centimeter on the map represents one kilometer on the ground. Many maps also show scale in the form of a scale bar which can be used to calculate any distance on the map. The scale dictates the level of detail shown by the map. Because maps are smaller than the areas they represent, symbols are used to indicate the features on the ground. Many symbols do not resemble the things the things they represent and so they are often explained in a key.

Map Coordinates Latitude Longitude

Lines of latitude and longitude form a grid from which the position of any point on the Earth’s surface can be measured.  An obvious reference point is the equator and latitude is the angle of a place north or south of it as measured from the center of the Earth. Lines of latitude form horizontal rings around the Earth parallel with the equator. They become shorter as they get closer to the poles. Lines of latitude divide up the Earth through its poles, like the segments of an orange. Each line is a great circle going right round the Earth. Lines of longitude have no obvious reference point such as the equator, so English navigators used the longitude or their home port, Greenwich, on the Thames near London. Longitude is still measured east or west of the Greenwich meridian. Early navigators used the stars to find out their position. Latitude was calculated from the heights of the stars in the sky or the position of the Sun as it rose, set or reached its zenith. Longitude is also measured against the stars but it is necessary to know the exact time because the stars move east to west across the sky. It was only after the perfection of the marine chronometer by John Harrison in the mid 18^th century that accurate longitude measurements, and hence accurate map making, become possible.

Map Making

A map is a schematic representation of an area. Maps are primarily used to help locate places or plan a journey, and can range from a plan of a farm to a map of the world. Maps may also be used to illustrate information about a particular area; for example, distribution of population, resources or climate. These specialized maps are known as thematic maps.

                In any map the way reality is represented depends on the amount of information it contains, the used of diagrams and other graphic devices, and the scale- the size of the map in relation to the area it shows. The oldest surviving maps were made by the Babylonians more than 4000 years ago. Many ancient mapmakers assumed that the Earth was flat, but the circumnavigation of the globe in the 15^th century led to great improvements in the accuracy of map making.  

                Maps show a range of information by the use of symbols and approximations. The first stage of map making is to construct a network of fixed points, from which everything else can be located. That way subsequent error will not accumulate and cause major distortions.  Before map makers had aerial photographs and satellite images to help them, the fixed points were plotted by a process called triangulation. Triangulation points are set up on landmarks such as hilltops. From the angles between these points, distance can be calculated without the need to take measurements on the ground. Adding vertical angle measurements give the heights. The height information on maps is normally shown as contours- lines linking points of the same elevation. It was by setting up a triangulation system across India from the coast to the Himalayas that cartographers first established the Mount Everest was the highest mountain in the world.  Today, satellite images provide the framework and maps are stored on computer so that they can be updated quickly without the need for redrawing.