Coordination & Homeostasis

Today we are going to study about Coordination & Homeostasis. First, We will give our attention to Coordination. Coordination is a very important thing to living beings to continue their lives. Animals unlike plants, have two different but related systems for coordination.

1. 1      Nervous system
2. 2      Endocrine system

Types of nervous organization of animals

               •    All multicellular animals except sponges use a network of nerve cells to gather

                   information about the  external environment, process and integrate that information, and

                   to issue signals to the  muscles and glands.

               •    Unicellular

                     No nervous organization ,ability to respond to stimuli. Cell functions as the receptor and

                   effecter.

               •    Multicellular

               •      Cnidaria – Development of nerve cells. Presence of a nerve net composed of multipolar

                   neurons, synapses. Conduction tracts in sea anemones. Development of receptors.

               •    Platyhelminthes – longitudinal solid nerve cords, organized  from a nerve ring or pair of

                   cerebral ganglion in the anterior region of the body - cephalization. Development of

                   receptors. E.g., eyespots, sensory cells.

               •    Annelids  Cerebral ganglia, double ventral nerve cord, ventral ganglia, giant nerve fibers

                     in some. Receptors E.g.,  eyes and sensory cells.

               •    Athropoda – More developed nervous system than that of Annelids. Cerebral ganglion

                   present. Well developed receptor organs of various type. E.g.,  eyes, antenna, palps

               •    Mollusca – Well developed nervous system .Consists of ganglia and nerve fibers

                     Presence of Receptor organs. E.g., well developed eyes

               •    Echinodermata – Radial nerve cord & nerve net

               •    Chordates – Single, dorsal, hollow nerve cord. Anterior region enlarged to form the brain.

                   Complexity increased gradually. Highest complexity is in mammals.

               

Transportation

       Transport is a very important action for living beings. So today we’ll study about Transportation..

          •   Water and minerals move upward through the xylem

          •   Dissolved sugars and hormones are transported in the phloem

          •    Methods of water and solute movement

          •    Basic principles underlying movement of water across membranes, phenomena of diffusion,

               imbibition, osmosis, mass flow and concept of water potential.

          •    Diffusion ; evaporation as an example

           •    Osmosis as a special kind of diffusion taking place when two solution of different concentrations       are  separated by a selectively permeable membrane which allows passage of water molecules but not of solute molecules.

               

           

                  

                   

               •    Imbibition as adsorption of water molecules to hydrophilic substances such as proteins, agar             etc,

               •    Mass flow as a method of movement of water and dissolved solutes in bulk (not in the form of

                   molecules) due to pressure gradient or gravity .

 Concept of water potential:

                   •    Any system containing water has a water potential. Water potential is related to kinetic energy of

                      water molecules, affected by factors like pressure, dissolved substances, hydrophilic substances,

                      etc.

                   •    Water potential is denoted by  Ψ  and is measured by the units of pressure (atm, Pa, M Pa).

                                               

                   •    Pure water at atmospheric pressure has the highest water potential.

                   •    Arbitrarily, the water potential of pure water at atmospheric pressure is considered as zero.

                   •    When solutes dissolve in water, the water potential is decreased and it becomes negative.

                   •    Therefore, the water potential of most naturally occurring aqueous systems is negative.

                   •    As the solute concentration increases, the water potential decreases.

                   •    Therefore, the water potential is inversely proportional to solute concentration of the system.

                   •    The component of water potential decreased due to the solute concentration is called solute

                      potential and is denoted by  Ψ s.

                                          

Diversity of respiratory structures

Animals have different respiratory structures depending mainly on the environment they live. So , we can study various type of respiratory structures  in animals. the area where gaseous exchange takes place with the environment is called the respiratory surface. An effective respiratory surface must have the following properties.

•   It must be permeable, and wet so that gases can pass through

•   It must be thin because diffusion is only efficient over the thin surfaces.

•   It should possess a large surface area to allow  sufficient volumes of gases  to be

      exchanged according to the organism’s need.

 •   It should possess a good blood supply.

Diffusion and surface to volume ratio

                      Respiratory gas exchange occurs due to diffusion. In small animals diffusion through

                      body surface is adequate as they are simple and the energy requirement is very low.

                      However, when surface volume ratio decreases, sufficient area is needed for gas

                      exchange and thus respiratory structures with large surface area were developed.

 Respiratory structures in animals

                      •   Body surface   e.g.,   Earthworm, flat worm

                      •   External gills   e.g.,   Polycheate worms, Arenicola tadpole of frog, salamander

                      •   Internal gills    e.g.,   Bony fish, lobster

                      •   Trachea       eg:    Insects, Millipedes, Centipedes

                      •   Book lungs    e.g.,   Spider, scorpion

                      •   Lungs         e.g.,   Human, Reptiles, Birds

Structure of the human digestive

•   Human digestive system consists of following parts. mouth, buccal cavity, pharynx,

                       esophagus, stomach, small intestine ,large intestine , rectum, anus

                     •   The location ,gross morphology and function of the above should be explained

                     •   Dentition

                     •   Structure and role of teeth

                     •   Action that should be taken to maintain dental health

                     •   Generalized structure of gut wall

                       •   Mucosa

                       •   Sub mucosa

                       •   Muscle layers

                       •   Serosa

                     •   Explain that the arrangement of tissue layers of the alimentary canal  is according to a

                       basic plan

                     •   Major variations in the basic plan occur in the mucosa. Variations in the stomach,

                       small intestine and large intestine should be explained  in relation to their functions

                     •   Peristalsis

                     •   Associated glands

Nutrition and its need

Nutrition is the process of acquiring energy and carbon. Organisms need energy for synthesis of substances for growth and repair. Ex: Protein synthesis, active transport of substances into and out of cells against  concentration gradient (Sodium-Potassium pump), electrical transmission of nerve impulses, mechanical contraction of muscle and beating of cilia and flagella. lets find out more about nutrition.

 Different modes of nutritional patterns in the living world:

                       •    Living organisms can be grouped on the basis of their source of energy or source

                        of carbon

                       •    Organisms which have an inorganic source of carbon  such as carbon dioxide are

                        described as autotrophic

                       •    Organisms having an organic source of carbon are described as heterotrophic

                       •   Organisms using light energy are described as phototrophic

                       •   Organisms using chemical energy are described as chemotrophic

•   Autotrophs synthesize their own organic  requirements from simple inorganic

                        materials

                       •   Autotrophic nutrition is of two types:

                        •   Photoautotrophic – Energy source is sunlight and carbon source is

                           carbondioxide.eg: cyanobacteria,  green bacteria ,green plants

                        •   Chemoautotrophic- energy source is chemical substances and carbon source is

                           Carbondioxide eg; nitrifying bacteria like  Nitrobacter, Nitrosomonas

                       •   Heterotrophic organisms feed on an organic source of carbon. All  animals and

                        fungi and majority of bacteria are heterotrophic

                        •    Modes of heterotrophic nutrition

                        •    There are three types:

                            •   Saprotrophic

                            •   Holozoic

                            •   Symbiotic

Systems of classification

The early classification systems were all artificial systems. Mostly based on human uses.

Aristotle was the first to classify organisms scientifically. He divided organisms into plants and

animals. Animals were further classified according to criteria such as mode of locomotion,

reproduction and presence or absence of red blood cells. Aristotle’s pupil Theophrastu

classified plants according to habit e.g. Trees, Shrubs and herbs, and according to lifespan e.g

annuals, biennials and perennials.Up to the time of Linnaeus scientists used many different methods.

 Carolus Linnaeus(1753), Swedish botanist, introduced binomial nomenclature and classified

about 6000 plants into a hierarchical order of taxa.;  Species,  genus, order, and class. His

 classification of flowering plants was based on the number of stamens and styles of flower. He

identified two kingdoms of organisms; plants and animals.With the discovery of microorganisms the scientists understood that there were organisms

which could not be assigned into either plants or animals. To get over this difficulty Ernest

Haeckel (1866) introduced a third kingdom: Protista. He also introduced the taxon Phylum and

classified many organisms.

With the discovery of electron microscope biologists identified prokaryotic and eukaryotic

cellular organization . Robert H Whittaker (1969) introduced five kingdom system of

biological classification; Monera, Protista, Fungi, Plantae and Animalia. His classification was based on nature of cellular organization, unicellular or multicellular nature and mode of

nutrition.

With the acceptance of Darwin’s theory on evolution and unitary origin of life, taxonomists

began to use natural systems. With recent advancement of molecular biology and the use of

molecular methods in studying evolutionary relationships it became apparent that in the very

early evolution, organisms had separated into three stocks which are now called Domains. Carl

Woese (1977) classified organisms into three Domains Archaea, Bacteria and Eukarya at a

 higher level over Kingdom

Hierarchy of  Taxa from Domains to Species.

                 In taxonomy each level of taxonomical hierarchy is called a taxon (plural-taxa) and  each taxon

                 has a rank and a name.

                 E.g.:  Class: Reptilia

                 Under the hierarchical system there are levels of taxa. Each Domain is divided into kingdoms.

                 Kingdom is divided into phyla (singular phylum), phylum into classes .etc. Many of these

                 categories may also be subdivided.

                  E.g.: Sub-family, Subspecies etc.

                  From domain to species, the number of shared characters among the members in the taxa

                 decreases. From species to domain, the number of individuals in the taxon increases.

Identification of organisms, classification and nomenclature.

  Need for classification and nomenclature

                   From the dawn of human civilization people must have begun to identify plants and animals

                   and named them, because their survival was dependent on the use of plants and animals.

                   Species were identified separately by their specific characters.

                   Major groups of plants and animals (like grasses, fishes, snakes, birds)were also identified

                   separately.

                   The names used were however varied depending on the language of the people and the place.

                   Biological study of organisms needs a unified system of classification and nomenclature.

                   Aristotle was the first person who classified organisms systematically.

Binomial nomenclature

                    With the advance of science and knowledge of biology, different scientists, Botanists and

                   zoologists used different methods of naming and classification of organisms. Most often a

                                                      

                   polynomial system was used, until 18th  century.

                    Carolous Linnaeus (1707-1778) proposed a binomial system of nomenclature of species,

                   which was accepted world wide.

                    The name of an organism has two parts

                     First is  the generic name and the second is specific epithet

                    Generic name is usually a noun and specific epithet an adjective describing a particular

                     feature. Example  Homo  means man,  sapiens  means intelligent

                     Related species have the same generic name with different specific epithets.  Dipterocarpus

                   means fruit with two wings,  zeylanicus  means endemic to Sri Lanka.

                 

 International codes of  Binominal nomenclature

                   Biologists have adopted sets of rules or Codes of nomenclature. These codes are slightly

                   different for plants, animals, bacteria and viruses. Some of the important rules for naming

                   plants, fungi and animals are as follows.

                   1. Two species of organisms cannot have the same name.

                   2. Each species has a generic name and a specific name, both together forming the species

                         name or scientific name.

                   3.  Name should be made up of  Latinized words written in the Roman script.

Energy relationships

Photosynthesis

Photosynthesis is a very importance reaction for Global let’s how to process photosynthesis from following points

                   •   Choloroplasts as the site of photosynthesis, its fine structure, thylakoids, grana and

                    stroma.

                   •   Pigments associated with absorption of light energy. Absorption spectrum of a pigment.

                    Compare with action spectrum of photosynthesis.

                   •   Mechanism of photosynthesis highlighting following points

                    •   Light reactions

                    •   Dark reactions

                    •   Light reactions

                      

Plant tissues and animal tissues

In multicellular organisms, the cells are organized into tissues, organs & organ systems. Tissue is a group of physically linked cells with common origin specialized for a particular function or functions. We can divide tissues to plant tissues and animal tissues.

Types of plant tissues, their structure & function

                    •   Plant tissues can be classified into two groups

                      •   Simple tissues – mainly one type of cells

                      •   Complex tissues – more than one type of cells

                    •   Simple plant tissues are divided into three groups

                        1. Parenchyma      2. Collenchyma     3. Sclerenchyma

                    •   The structure, function and distribution of simple plant tissues.

                    •   Modified parenchyma cells and their distribution and function

                    •   Complex plant tissues are divided into two groups.

                         1. Xylem               2. Phloem

                    •   Structure, function and distribution of complex plant tissues.

                    •   Observation and identification of  different plant tissues under light microscop

Main types of animal tissues and their characters.

    

Structures and functions of sub cellular components.

As we know all organisms are composed of cells. So it is very important thing to study about the cell.  A cell has sub cellular units. All sub cellular units have special structure and functions. Let’s explore that structure and functions one by one.

Structures and functions of organelles and sub cellular components.

   Cell wall

                          •    Outer envelope of plant cell. Animal cells do not have cell walls

                          •    Made up of cellulose and pectin. Hemicellulose, lignin suberin may also be

                             present.

                          •    May have primary and secondary walls. Explain the chemical components of

                             middle lamella, primary cell wall and secondary cell wall.

                          •    Cell wall has pits through which cytoplasm of adjoining cells join through

                             plasmodesmata.

                          •    Functions of cell wall.

                      •    Plasma membrane

                          •    Outer limit of protoplasm.

                          •    Illustrate the structure of the fluid mosaic model of the plasma membrane,

                             consisting of a bilayer of lipids, integral proteins and peripheral proteins.

                             Movable lipids give the fluidity whereas the arrangement of protein molecules

                             gives the mosaic structure.

                    

                          •    Other membranes in the cell also have the same structure.

                          •   Dynamic boundary of cell.

                             •   Permits the entry of water, ions and certain organic molecules.

                             •   Regulates the exit of waste materials.

                             •   Maintains an osmotic balance within the cell.

                             •   Receives information through receptors and transmit signals to co-ordinate

                                activities between cells.

Cells and cellular organization

 Cell theory.

All organisms are composed of cells, some of a single cell some of many cells. Recall the hierarchy of life, the levels of organization mentioned earlier. The basic  unit which can be called “living” is the cell, which may form a single celled organism (e.g.,  Chlamydomonas , Yeast) or a multicellular plant or animal. The cell is the basic structural and functional unit of life. The level of organization of matter represented by a cell shows all the characteristics of life. Any stage below level of a cell cannot be considered living, whether it is a single celled organism or multicellular  plant or an animal.

History and presentation of Cell theory

•    Robert Hooke (1663), while trying to understand why, cork which is a solid substance can float, examined thin slices using a microscope and found that they are      made up of ‘pores’ and coined the term ‘cells’ to describe the pores.

•    Anton Van Leeuwenhook (1650), a contemporary of  Robert Hooke was the first to describe and record  living single celled organisms,  Euglena  & bacteria

•    Matthias Schleiden (1831), a botanist, studying plant tissues concluded that all plants are made up of cells.

 •    Theodore Schwann (1839), a zoologist and Shleiden (1832), concluded that animal tissues are  also made up of cells.

•    Schleiden and Schwann presented the  ‘Cell Theory’ which included the following.

The main organic compounds of organisms

We can find four major organic compounds  in organisms. That major organic compounds have basic chemical nature and functions. We will study them one by one.

The major organic compounds that found in organisms are,

                    •    Carbohydrates

                    •    Lipids

                    •    Proteins

                    •    Nucleic acids

 These  major organic compounds considered as major biological molecules.

  Carbohydrates

                    •   Most abundant organic matter on earth

                    •   The substances that we know as sugars and flour in day-to-day life are examples

                    •   Major elemental composition is C,H,O

                    •   General formula C_x(H₂O)_y - Hydrates of carbon contains the same proportions of

                         H:O (2:1)   found in water

                    •   Monosaccharides, disaccharides and polysaccharides are the three main classes

                         of  carbohydrates                                    

             Monosaccharides

                      •   Name monosaccharides  according to the number of C atoms as; Triose

                          (3C ) e.g. Glyceraldehyde, Tetrose (4C)  e.g. Erythrose - rare in nature,

                          Pentose (5C)  e.g.Ribose,  Ribulose, Hexose(6C) e.g. glucose, fructose, galactose.

                      •   All Monosaccharides are reducing sugars  

                      

             Disaccharides

                      •  Maltose, Lactose are reducing sugars, Sucrose is not a reducing sugar.

             Polysaccharides

                       •     Polysaccharides structured as, 1-4 glycosidic bonds and 1-6

                             glycosidic bonds. Straight chains and branched chain structure. Basic

                             structure and functions of starch, glycogen and cellulose.  Amylase

                             activity on starch. Inulin as an example of  another polysaccharide and

                             hemicellulose, pectin and chitin as important polysaccharide derivatives  

                               

    

Importance of water for life.

As you know, water is essential thing for our daily life. We can't live without water. Why water importance for every living beings? be course it is the most abundant inorganic compound in living matter.
We use water for drink,food process, cleans, and many more works. lets explore functions of water in organisms.

The main functions of water in organisms

We can see 4 main functions of water in organisms. they are,

1. Component of  protoplasm
2. Solvent
3. Reactant
4. Maintaining turgidity

Other than, We can find many functions of water. I created a table with that functions. that table includes water's property role and examples. you can study it easily.

Characteristics and variations of Living organisms

Do you can identify a Living organisms?..yes.. all  living organisms can identify another living organisms. but scientist couldn't give a one sentence or paragraph to describe living organisms. so,We have to learn variations and Characteristics to describe living organisms. lets explore variations and Characteristics of living organisms.

Variations of Living organisms

Living organisms show a wide range of variation in size, shape, form and distribution
examples:
Size – Bacteria – 0.25   – 2   μ   to  Giant Sequoia (Giant Red Wood)– 100 m
Shape – Organisms are diverse in shape
Form – a cellular , unicellular, multi cellular
Distribution – Terrestrial, aquatic, arboreal, aerial

 Characteristics of living organisms

We can see following  Characteristics from living organisms study them carefully.

                   (1)   Order and organization
                       From molecular level to biosphere there is an order and organization in organisms to
                       perform their biological activities efficiently

                 (2)   Metabolism
                       The sum of all chemical activities taking place in an organism is  its metabolism. It
                       includes catabolic reactions and anabolic reactions.

                 (3)   Growth and development
                       All organisms begin their life as a single cell. During growth an irreversible increase
                       in dry mass occurs, which is characterized only by the living. Growth and
                       development are two consequent processes that happen in the life span of organisms.

Introduction to Biology and “Biology College”

You are warmly welcome to "Biology College". first, I’ll say about me. I'm a science student studying in biological science. I'm like to do researches and practicals in biology. so I thought to share my knowledge via my Biology College blog. if you are prefer to biology I'm sure you will like to this blog.

Let’s see about biology. Biology is a very beautiful and interesting subject that studying about the life. This subject divide to many sections as example microbiology, biochemistry, astrobiology...ect: As you know biology very useful to our daily life. It helps to us to continue a healthy life. Do you know the importance and main targets from biology? lets collect some of them.

 The importance and main targets of biology

•   Understanding biological diversity :

                 There has been life on earth for over 3.5 billion years. We should understand that there are around 30 million species of animals and plants in the world. There is a dynamic relationship between the world of life and the inanimate world.

 •   Understanding the human body and its functions:

                 We should be able to appreciate the organization of the human body, how systems within the body are interconnected and the way structure is related to function.

 •   Management of natural resources and environment:

                 The natural resources are limited and with the current increase in

                 growth of human population there is a threat of depletion of natural resources. Destruction of Ozone layer in the atmosphere, acid rain, global warming caused by increasing concentrations of CO  in the atmosphere, pollution of rivers and underground water supplies leading to a dearth in drinking water in the future etc, are some of the results.