Latitude, Longitude, Earthquake, Volcanoes, Branches of Biology, Characteristics of Living Organisms

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Definition: It is the distance on the surface of the earth measured in degrees north and south of the equator. The equator is at zero degree where the poles are at 90 degree. The latitude of the North Pole is 900 North and that of South Pole is 900 South.

Characteristics of Lines of Latitudes

  • All lines of latitudes are parallel to the equator as well as parallel to one another.
  • Parallels in the north of the equator are north latitudes while those in the south of equator are known as south latitudes.
  • They are drawn on the globe as circles running in east to west direction.
  • The length of the equator is the maxim um and it goes on reducing till the pole is only a point.


  • Definition: The distance on the earth՚s surface measures in degrees east and west of a line joining the geographical north and south poles and passing through Greenwich in England. Greenwich is at zero degrees longitude.
  • The sun rays have highest altitude simultaneously on all the places at a particular line of longitude as a result of which these are also called as Meridians (Meridian is a Latin word which means Mid-way) . Among the latitude, equator is the longest and is taken as reference line. But all the lines of longitude are of the same length and selecting a longitude as lines of reference is a serious problem.


  • Earthquakes are those movements of the earth crust which make the ground vibrated and shake backwards and forwards or in simple words an earthquake is trembling in the earth.
  • The shocks waves are generated at a point within the crust called the focus, and the point on the earth՚s surface vertically above the focus is called the epicenter of the earthquake.
  • The shock waves travel in all directions from the focus. On the earth՚s surface, the shaking is the strongest near the epicenter. These waves are detected by seismograph.

Occurrence of Earthquake

  • Earthquakes occur when rocks subjected to great stress suddenly break, releasing the accumulated energy, which shakes the ground. Vibrations spread out from the epicenter like ripples in water.
  • It may also be caused by movements of the plates, resulting from convection currents in the hot mantle of the earth.
  • Earthquakes are also associated with volcanic activity-eruption of magma. Collapse of mines can also produce small earthquakes.


An opening in the earth՚s crust through which molten lava, ash, and gases are ejected.

Occurrence of Volcanoes

  • Rocks below the Earth have a very high temperature.
  • The great pressure upon these keeps them in a semi-solid state.
  • If the pressure weakens, then some of rocks become liquid.
  • This liquid is called magma.
  • The magma forces its way into cracks of the crust and may either reach the surface of the earth where it forms lava or flow out.

Types of Volcanoes On The Basis Of Activity: There are three types of volcanoes on the basis of volcanic activity, which are as under.

  • Active Volcanoes: Volcanoes are said to be active when they frequently erupt or at least when they have erupted within recent time.
  • Dormant Volcanoes: The volcanoes that have been known to erupt and show signs of possible eruption in the future are describes as dormant volcanoes.
  • Extinct Volcanoes: The volcanoes that have not erupted at all in historic times but retain the features of volcanoes are termed as extinct volcanoes.
  • Causes of The volcanoes Eruptions:
    • Seafloor spreading
    • Convergence of lithospheric plates
    • Percolation of cold water
    • Orogenic Movements
    • High temperature in the interior of the Earth.


Igneous Rocks

  • The word igneous means the fires and the rocks formed by solidification of molten rock material known as magma are known as igneous rocks.
  • The first minerals to crystalize out of the melt are high-temperature minerals-the olivine՚s and pyroxenes, which are silicates of magnesium and iron.
  • They tend to be denser than magma and so they sink, leaving the remaining fluid deficient in magnesium and iron.
  • The next group of minerals to solidify are the feldspars (silicates minerals of potassium, sodium, calcium and aluminium) ; the magma thus loses its metallic constituents first.
  • Finally, any remaining silica crystalizes out as quartz.
  • The entire solidification process therefore results in dense iron-and magnesium-rich rocks and less dense silica rich rocks from the same original fluid.
  • In this way, different types of rocks can be seen in the same rock mass.
  • The most important igneous rocks are:
    • Granite rocks
    • Gabboro rocks
    • Basalt rocks

Sedimentary Rocks

  • Sedimentary rocks are formed from the deposition and compaction or lithification of rocks and mineral grains derived from other rocks.
  • These grains broke away from existing rocks by the action of water, wind and ice.
  • Many sedimentary rocks begin their existence as loose deposits of sand or gravel at the bottom of a sea or lake, on beach, or in a desert.
  • Later the sediment is lithified i.e.. compressed into a rock.

Following are the major classes of sedimentary rocks:

  • Calcareous sedimentary rocks
  • Carbonaceous sedimentary rocks
  • Siliceous sedimentary rocks
  • Ferruginous sedimentary rocks
  • Arenaceous sedimentary rocks
  • Argillaceous sedimentary rocks
  • Rudaceous sedimentary rocks

Metamorphic Rocks

  • The word metamorphic has been derived from two Greek words Meta means change and Morpha means shape.
  • Thus metamorphic rocks include those rocks that have been changed either in form or composition without disintegration.
  • Metamorphic rocks are formed from igneous as well as sedimentary rocks but are different from them.


  • Sandstone, made of quartz grains and silica cement, becomes quartzite, a very hard metaphoric rock that resist weathering.
  • Limestone is converted into much denser and harder marble.
  • Mica, an igneous rock, is converted into schist after metamorphosis.
  • Sedimentary rock slate is converted into a slightly higher grade metamorphic rock phyllite.

Branches of Biology

  • Zoology: Zoology is that branch of biology which deals with the study of animals.
  • Botany: Botany is that branch of biology which deals with the study of plants.
  • Microbiology: It is the branch of biology which deals with the study of microorganisms such as viruses, bacteria etc.
  • Morphology: It deals with the shape and structure of living organisms.
  • Histology: It is the microscopic study of tissues of plants and animals.
  • Cytology: It deals with the structure of cell and organelles present inside the cell.
  • Physiology: It deals with the study of functions of different parts of plants and animals.
  • Ecology: It is the science of ecosystem and explains the relationship between organisms and their environment.
  • Taxonomy: It deals with the naming and classification of organisms.
  • Genetics: It deals with the study of heredity and variations.
  • Biotechnology: It deals with the application of biological processes.
  • Haematology: Study of blood and its constituent cells.
  • Geology: Study of features and properties of earth and its constituents rocks

Characteristics of Living Organisms

Following are the main characteristics of living beings which are not present in non-living organisms.

  • Metabolism
  • Growth
  • Irritability
  • Reproduction
  • Movement
  • Nutrition
  • Respiration
  • Excretion

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