Characteristic of Enzyme

➢ Chemically enzymes are commonly globular proteins.

➢ Some RNA molecules called ribozymes can also be enzymes. 

➢ These are generally found in the nuclear region of cells and catalyze the splitting of RNA molecules. 

➢ Enzymes are catalysts that breakdown or synthesize more complex chemical compounds. 

➢ They allow chemical reactions to occur fast enough to support life. 

➢ Enzymes speed up the rate of chemical reactions because they lower the energy of activation, the energy that must be supplied in order for molecules to react with one another. 

➢ Anything that an enzyme normally combines with is called a substrate. 

➢ Enzymes are very effective. 

➢ An enzyme generally catalyze between 1 and 10,000 molecules of substrate per second. 

➢ Enzymes are only present in small amounts in the cell since they are not altered during their reactions. 

➢ They are highly specific for their substrate. Generally there is one specific enzyme for each specific chemical reaction

Significance of Mitosis

➢Mitosis is important for sexual reproduction indirectly. 

➢ It allows the sexually reproducing organism to grow and develop from a single cell into a sexually mature individual. 

➢ Mitosis permits organisms to continue to reproduce through the generations. 

➢ It is a same division through which identical daughter cells are produced having the same amount and type of genetic constitution as that of the parent cell. 

➢ It is responsible for growth and development of multi-cellular organisms from a single-celled zygote. ➢ The number of chromosomes remains the same in all the cells produced by this division. 

➢ Thus, the daughter cells retain the same characters as those of the parent cell. 

➢ It helps the cell in maintaining proper size. 

➢ Mitosis helps in repairing wear and tear in body tissues, replacement of damaged or lost part, healing of wounds and regeneration of detached parts (as in tail of a lizards). 

➢ It is a method of multiplication in unicellular organisms. 

➢ If mitosis remains unchecked it may result in uncontrolled growth of cells leading to cancer or tumor.

Kingdom Monera

 Monera is a kingdom that contains unicellular organisms with a prokaryotic cell organization (having no nuclear membrane), such as bacteria. They are single-celled organisms with no true nuclear membrane (prokaryotic organisms. 

Characteristics 

➢ They are typically unicellular organisms (but one group is mycelial).

➢ The genetic material in these organisms is the naked circular DNA. 

➢ A nuclear envelope is absent. 

➢ Both, ribosomes and simple chromatophores are the only subcellular organelles in the cytoplasm. 

➢ Sap vacuoles do not occur. Instead, gas vacuole may be present. 

➢ The predominant mode of nutrition is absorptive but some groups are photosynthetic (holophytic) and chemosynthetic. 

➢ The organisms are non-motile or move by the beating of simple flagella or by gliding

Limitation of Two Kingdom system of Classification

1. Some organisms share the characteristics of both animals and plants. Example Euglena and Sponges. In Euglena, certain species contain chlorophyll and are autotrophic similar to plants. However similar to animals they are dependent on an exterior supply of vitamins B, and B12 that they cannot synthesize themselves. 

2. Fungi are a class of organisms that contain features of their own. They lack chlorophyll. They are heterotrophic similar to animals. They are placed all along with green plants. 

3. Most of the primitive organisms like bacteria did not fit into either group and organisms similar to slime molds are amoeboid however form fruiting bodies alike to fungi. 

4. The status of virus whether they are non-living or living is a point of debate even today.

Biodiversity and its Importance

 Biodiversity

It is the shortened form of two words biological and diversity. It refers to all the variety of life that can be found on Earth (plants, animals, fungi and microorganisms) as well as to the communities that they form and the habitats in which they live. According to biologist there is more than 100 million kind of organisms, biodiversity depend on climate, altitude and structure of soil. Tropical areas of earth have richer biodiversity whereas Polar areas have less. There are 23, 000 different animals and 6000 plants in Pakistan.

Importance of Biodiversity

➢ Biodiversity provide great variety of food for human (crop, livestock, forestry and fish). 

➢ It play a very key role in health of human and animals. We used fungi, plants and animals as medicines such as streptomycin, neomycin and erythromycin are obtained from fungi, drugs like caffeine, morphine, quinine etc. are acquired from plants. 

➢ It is play very key role in the production of industrial material such as building material, fibers, dyes, resin, gums, adhesive rubber and oil are get from plants. 

➢ It is a vital constituent of ecosystem. Species show contact among them, each species has been play a particular role in ecosystem. 

➢ Lose of species make the ecosystem less productive e.g. water cycle, nitrogen etc. going on ecosystem. 

➢ Fertility of soil, balanced climate and several other features depend on biodiversity.

Herbarium

• Herbarium is a store house of collected plant specimens which are dried, pressed and preserved on herbarium sheets.
• The sheets are systematically arranged according to an accepted system of classification.
• The herbarium sheets contain a label on the right-hand side at the lower corner.
• The label contains the following information: 
• Date and place of the specimen collected o English, local and botanical names of the plant 
• Family
• Collector’s name
• Preparation of Herbarium: 
• Plants with fully grown leaves and complete inflorescence are collected in a metallic vasculum or polythene bags to preserve moisture.
• Plant specimens are then dried by pressing them in newspaper folders. 
• When specimens are partially dehydrated, they are poisoned by using chemicals such as mercuric chloride, DDT or carbon disulphide to prevent them from any microbes.
• Fleshy organs are stored in FAA mixture (formalin, acetic acid, ethyl alcohol and water).
• Dried specimens are then glued on the herbarium sheets. o The standard international size of a herbarium sheet is 41 × 29 cm.
• On the right-hand side, at the lower corner, a label containing all the data is fixed. 
• Fragment packets, i.e. small paper envelops are also attached to the sheet to preserve loose parts such as seeds.
• The sheet is then covered with a polythene bag to avoid tearing of delicate plant parts.
• Then sheets are arranged according to the accepted system of classification. In India, the Bentham–Hooker system is used in which species of the same genus are arranged together.
• Uses of Herbarium: 
• Provides information on the local flora and the flora of other regions o Provides correct and authentic information of unknown plants o Used as a quick referral for taxonomic studies
• Institutes teaching botany have herbaria. Royal Botanical Gardens, Kew, has the largest herbarium.

Taxonomic Hierarchy

Introduction

The term Taxonomy was coined by Augustin Pyramus de Candolle. Taxonomy is the science of classification of organisms. Classification of organisms is done by Biologists based on evolutionary relationships and shared features among the organisms.

The fundamental unit of life on Earth is refers to as the species. The species is a population or series of populations whose members are able to interbreed freely under natural conditions and who do not breed with other species.

Closely related species are grouped as genus (pl. genera); while closely related genera are grouped as family and so on. This type of grouping makes up the classification hierarchy. The genus and species names are always either italicized or underlined, with the genus name Capitalized and the species name in lower case.

Species are grouped into more comprehensive taxa, these taxa are grouped into larger taxa so that the classification is a hierarchy of a system of units that increase from first level to the next higher level.

Taxonomic hierarchy

Taxonomic Hierarchy or Linnaean hierarchy categories are introduced by Linnaeus. It is defined as arrangement of categories in a decreasing or increasing order from kingdom level to species level and vice versa. Kingdom is the highest rank given in the hierarchy then the levels division, class, order, family, genus and species follow. Species is the lowest rank given in the Hierarchy.

The hierarchy has two categories namely, obligate (main) and intermediate (intra).

Ø  In obligate category, hierarchy is followed strictly. Here the levels range from kingdom to species.

Ø  In intermediate category, hierarchy is not followed strictly. The levels are added in between the list such as sub-division, super-family, super-class, sub-order, sub-species and so on.

The following are seven main or obligate categories used in any plan of classification. They are known as the supra-specific groups.

1. Kingdom

      2. Division

            3. Class

                 4. Order

                     5. Family

                           6. Genus

                                 7. Species

v Species: 

Group of organisms which are similar in form, shape and reproductive features are called species.  This similarity is important so as to produce fertile offsprings. Offsprings are sterile when a hybrid is produced. The level species is followed by subspecies, clines and demes. These categories are inferior when compared to species.

v Genus:

Genus is a group of related species. Some genera may have only one species (Monotypic) whereas some may have more than one species (polytypic).

v Family: 

Family is the collection of related genera.

v Order:

One or more than one related families form an order.

v Class:

One or more than one related orders form a class.

v Division: 

Division is the term used for plants while its synonym phylum is used for animals. It is a collection of related classes.

v Kingdom: 

Kingdom is the uppermost taxonomic category. For example all the plants are included in Kingdom Plantae. Taxon is the unit of classification that denotes group of organisms based on observable features.

Under species we have other groups termed as infra specific groups. The following is the list of intermediate or infra specific groups,

       1. Species

            2. Subspecies

                   3. Clines

                        4. Demes

Various methods used to recognize and categorize organisms are called as Taxonomic aids. Identification of organisms is a tiresome process. Taxonomic keys are used for identification of organisms. Taxonomic key is a long table of statements with different features to recognize the organisms. The features which are related to a particular organism are chosen and then the organism is grouped into the relevant category.