Phosphoglycerides

Prep Army
-
0

Phosphoglycerides

The second largest class of complex lipids consists of the phosphoglycerides also called as glycerophosphates. They are the major components of biological membranes. They control the permeability of plant and animal cell. They consist of Sn glycerol-3-phosphate. The fatty acids are esterified at C-1 and C2 position, and phosphate at C-3. They must contain one phosphate as the name suggests. As these compounds contain a polar head in addition to their non-polar hydrocarbon chain, they are called amphipathic or polar lipids. The parent compound is phosphatidic acid The most abundant phosphoglyceride in plants and animals is phosphatidylethanolamine and phosphatidylcholine (lecithin). Lecithin’s contains palmitic, stearic, oleic, linoleic and arachidonic acid as the most abundant fatty acids. They are methylating agents and are thought to have the active role in nerve impulse. Cardiolipins are components of membranes of heart cells. These are the phospholipids in which there is ether linkage instead of ester linkage at C-1 of glycerol. It contains alfa, beta-unsaturated alkenyl hydrocarbon (cis bond) joined by ether linkage. About half of the heart phospholipids are plasmalogens. Their exact function is not known, perhaps it confers resistance to lipases. Phosphoglycerides can be hydrolyzed Phosphoglycerides can be hydrolyzed into their components by enzymes called phospholipases as shown below. They are specific for specific sites. Lysolecithin can be obtained by the action of lecithinase, which removes fatty acids from C-2 position and is present in snake venom and the sting of bees. The lecithinase leads to hemolysis of red blood cell, as the lecithin is the major component of membranes.

Sphingolipids

Sphingomyelins

The most common sphingolipids are ceramides having either a phosphocholine or phosphoenol moiety so that they can also be classified as sphingophospholipids. The membranous myelin sheath that surrounds and electricity insulate many nervous cell axons is particularly rich in sphingomyelin

Cerebrosides

The simplest sphingolipids are ceramides with head groups that consist of single sugar residue. Galactocerebroside is most prevalent in the neuronal cell membrane of the brain and has a beta-D-galactose head group. The glucocerebrosides contain glucose as the moiety.

Gangliosides

They are the most complex glycosphingolipids. They are the ceramides attached with oligosaccharides that include at least one sialic acid residue. The gangliosides are primary components of cell surface membrane and constitute a significant fraction (6%) of brain lipids. They have considerable physiological functions. Their carbohydrate head group, which extends beyond the surface of cell membrane, act as a specific receptor for pituitary glycoprotein hormones that regulate a number of important physiological functions. They are also a specific determinant of cell-cell recognition.

Glycolipids

They contain one or more sugar residues attached to either diacylglycerol or a sphingosine derivative and do not contain phosphate. For example, glucoglycerides are the glycosides of diacylglycerol.

Waxes

Waxes are simple lipids containing one molecule of fatty acid esterified with one molecule of a high molecular weight monohydroxy alcohol or sterol. They differ from fats and oils in that the glycerol is replaced with high molecular weight alcohol or sterol. They are saponifiable and less prone to atmospheric oxidation. Beeswax, carnauba wax (from carnauba plant) and spermaceti (from sperm whale) are examples of true wax. Beeswax contains palmitic acid esterified with hexacosanol or triacontanol. Carnauba wax is the hardest known wax which consists of fatty acid esterified with tetratriacontanol. Waxes are found as protective coating on the skin, fur, and feathers of animals and birds and on the leaves and fruits of higher plants, and exoskeleton of many insects.

Steroids

Steroids which are mostly of eukaryotic origin, are derivative so cyclopentanoperhydrophenanthrene, are a compound that consists of four fused rings. All steroid originate from triterpene squalene. Various steroids vary in respect of side chain attached at C-17.

Cholesterol

This is the most abundant steroid in animals, distributed in the plasma membrane. It is found in less extent in cell organelle membranes as compared to the plasma membrane. It is further classified as sterol as it has C3-OH group and its branched aliphatic side chain of 8 to 10 carbon atoms at C17. In plasma, it is esterified to fatty acid as a cholesteryl ester. The solubility of cholesterol is low in the water, at 25°C, i.e., 0.2mg/100ml. In plasma, the concentration is 150-200 mg/100 ml in normal adult human beings. This high solubility is due to its association with proteins forming LDL (Low-density lipoproteins) and VLDL (Very Low-Density Lipoproteins). It has been observed that 30% cholesterol is existing in free form and rest as fatty acyl derivative. This molecule is of great interest to the scientist world over as it leads to high risk of atherosclerosis (thickening of arteries) and hence heart attack. About thirteen Nobel prizes have been awarded for the work of cholesterol. Plants contain very little cholesterol but synthesize other sterols. Yeast and fungi also synthesize sterols, which differ from cholesterol in their aliphatic side chain and number of double bonds. Prokaryotes contain little, if any, sterol.

Sterol hormones

In mammals, cholesterol is a precursor of steroidal hormones, substances that regulate a great variety of physiological functions. The important steroidal hormones are a corticosteroid, testosterone, estradiol, and progesterone. The important bile salt derived from these sterols in the animal system are cholic acid, chenodeoxycholic acid etc. They are the important constituents of the bile juice and help in the digestion of lipids in the intestine.

Prostaglandins

The very name is prostaglandins was coined as they were recognized first in prostate glands. They are C20 unsaturated hydrocarboxylic acids with a cyclopentane ring in the molecule. The parent compound is prostanoic acid. Arachidonic acid is a precursor of prostaglandins. The structure of arachidonic acid is as shown below. It is synthesized from the linoleic acid (essential fatty acid). They are three major classes of primary prostaglandins i.e. A, E (ether soluble), F (phosphate buffer soluble). One of the example is PGE1 The lipid bilayer is formed when the molecules have a cross-section of head and tail similar. This is normally with the phospholipids, sphingolipids, glycolipids, and gangliosides. Proteins are embedded inside these lipid layers like ice (proteins) floating in water (Sea of lipid). The superficial proteins are called extrinsic and those crossing through are called intrinsic. They are natural mediation of inflammation. To stop inflammation corticosteroid that inhibits their biosynthesis are used as an anti-inflammatory. Aspirin also inhibits oxygenase that forms prostaglandins from arachidonic acid.

Terpenes

They are the class of lipids which are non-saponifiable in nature. They are made multiple units of five carbon hydrocarbon, isoprene (2-methyl-1, 3butadiene). They have arranged either head to tail or tail to tail containing two, three, four six or eight units forming linear or cyclic compounds.
  • Monoterpenes geraniol, limonene, and menthol are the major components of geranium, lemon oil, clove oil and mint oil.
  • The diterpene phytol, a linear terpenoid is a component of photosynthetic pigment chlorophyll.
  • The beta-carotene (tetraterpene containing eight isoprene units) is a precursor of Vit-A
  • Another class includes fat-soluble vitamin-E and Vit-K
  • Ubiquinone or coenzyme-Q acts as the hydrogen carrier in oxidative phosphorylation in mitochondria.

Membranes

The thin impermeable barrier around the cytoplasm or cell organelles is termed as membranes. They chiefly constitute amphipathic lipids and proteins. Among the amphipathic lipids, glycerophospholipids, sphingolipids, and sterol are the chief constituents. When they are mixed with water, they aggregate to be away from water. They align in such a manner that their hydrophobic region aggregate and polar region interacting with water. Micelles are relatively small, a spherical structure involving a few dozen to few hundred molecules that have cone shape as shown. The free fatty acids and lysophospholipids usually the micelles.  

Tree

Prep Army
-
0
Tree

Tree

The tree is one of the categories of plants. Plants are classified into 3 categories i.e., herbs, shrubs, and trees.
  1. Herbs: Herb is a plant whose height is not more than 1 meter and always green and tender. Herbs are classified as annuals, biennials, and perennials.
  2. Shrubs: Shrub is the category of plant, who have a woody stem but short stature and its branching start from the base. A shrub plant doesn’t grow more than 6 meters in height.
  3. Tree: It is woody perennial. It has a single well-defined stem (bole or trunk) and a more or less definite crown. The height of the tree is usually more than 6 meters in height.

Parts of Tree

  1. Crown
  2. Stem
  3. Root

Tree Crown

The crown is the upper branchy part of a tree above the bole. It is formed of foliage of the branches springing from the bole.

Shape and size of Crown

The shape and size of the crowns of trees vary with species and the conditions in which they grow. Phoenix, Cocos, and Borassus have crowns of large leaves at the tops of cylindrical unbranched stems. This characteristic distinguishes them from other forest trees which are generally much branched. In Chir, Deodar and some other conifers, the lower branches are longer while the upper branches are gradually shorter, giving the crown a conical shape. On the other hand, the crowns of Mangifera indica, Azadirachta indica, Tamarindus indica, Madhuca indica, etc., are spherical in shape. In Albizzia stipulata the crown is broad and flat-topped, while in Abies pindrow it is moer or less cylindrical. Except for the palms, the crowns of other trees are affected by the situation in which they grow. Normally, the trees grew in open have large branches and big crowns, while those in dense forests have smaller branches and smaller crows because the branches on the lower part of the bole die out gradually due to shade and the crowns are limited to the upper part of the bole the tree. The size of the crown depends upon crown development which is “the expansion of crown measured as crown length and crown length”.

Mode of branching (Tree)

The mode of branching varies with species and sometimes, it is characteristic of the genus or the family. In most of the species, it is absolutely unsystematic. In species with opposite leaves, the branches are also in opposite pairs, though sometimes, this is visible only in the upper branches. Some species, e.g., Bombex ceiba and Pinus wallichiana, with alternate leaves sometimes develop branches in whorls. The angle that the branches make with the stem, is also specific character. Though in most cases, the branches make an angle of 60° to 70° with the stem, yet in some species. e.g., Populus nigra, cuppressus sempervirens, they make angles upto 20° to 30°. In quite a few species, e.g., old deodar and Duabanga sonneratiodes, the branches are almost horizontal and form terraces of foliage, while in other, e.g., Anogeissus pendula, Terminalia myriocarpa, leading shoot of young deodar and branchlets and twigs of spruce, they are drooping downwards. The size and the number of branches also varies with species. While in some species branches are thin and twiggy in other they are thick. Some species have large number of branches while others have only a few. The larger the number of branches and thicker the branches, the more the wood is knotty; this is considered as a defect in timber for several purposes.

Leaf color, size, and texture

Normally the mature leaves are green. The shade of color of two surfacce of leaf is often different, the lower being often paler than the upper. In addition to the difference in shade, the lower surfacce of the leaf is sometimes covered with white (e.g., in Quercus incana) or rusty brown tomentum (e.g., in Quercus semicarpifolia). Some species have characteristic attractive color in their young leaves. For example, young leaves of Quercus incana are pinkish or purplish, those of Acer caesium, Schleichera oleosa bright red, those of mango brown and those of Cassia fistula dark red-brown. In some species, leaves undergo a striking change in color before falling from the tree; such color are called ‘autumn tints‘ and help the forester in recognizing the species form a distance. For example, before falling the leaves of Lannea coromandelica turn yellow, those of Anogeissus latifolia dark red or bronze, and sapium sebiferum beautiful red, purple and orange. But quite a few species, e.g., Elaeocarpus, Bischoffia are charcterized by the presence of a few conspicuous red leaves in almost all seasons.

Leaf Size

Size of leaf depends upon rainfall and the species. As a rule, the leaves in low rainfall areas are small while they are generally bigger in heavy rainfall areas. In some species, e.g., teak, Dillenia, the leaves are bigger than the usual size of most leaves. Leaves of most conifers are needle shaped and that is why they are called needles.

Leaf Texture

While the texture of leaves of some species is soft and membranous, it is hard and coriaceous in others. The membranous and soft leaves of species, e.g., Grewia, Ougeinia, Anogeissus, etc., on falling not only decompose rapidly and get mixed up with the soil but hasten the decomposition of the hard and coriaceous leaves of species, e.g., sal and conifers, which otherwise, decompose very slowly and create problem for natural regeneration.

Leaf shedding

 All trees shed their old leaves regularly and produce new leaves. On the basis of the presence or absence of old green leaves at the time when the new leaves are produced, the trees and other plants are classified into Deciduous and Evergreen.

Deciduous Trees

Deciduous: A tree or plant which remains leafless for some time during the years. It produces the new flush of leaves after all the old leaves shed and it has remained leafless for some time. The leafless period varies with species and situation. For eg., Sal is leafless for about a week or ten days while Hymenodictyon excelsum remain leafless for about six months. Even in the same species, different trees remain leafless for the different period because of their situation.

Evergreen Trees

Evergreen: A perennial plant which is never entirely without green foliage, the old leaves persisting until a new set has appeared. The persistence of the old green leaves after the new leaves have been produced. It depends upon species and in the same species upon the environment. For e.g., in a chair, the old leaves persist from one year five months to two or three years but in deodar, they persist for five or six years. On lower altitudes, due to higher temperature, chir, which is normally evergreen, become deciduous.

Tree Stem or Tree trunk

The stem is defined as the “the principal axis of plant from which buds and shoots are developed; in trees, stem, bole, and trunk are synonymous’ but bole is ‘sometimes used to refer’ to only lower part of the stem upto a point where the main branches are given off i.e., as a synonymous for clear or clean bole. The clear or clean bole is defined as the part of the bole that is free of branches.

Shape and length of Stem (Tree)

The shape and length of the stem vary with species and the situation in which the tree grows. Some species have long and straight stem with relatively few branches, while others have the stem which is crooked and /or much branched. Normally the stem is thicker at the base and thinner in the upper portion of the tree.
Taper
The decrease in diameter of the stem of a tree or of a log from the base upwards, is known as a taper. This due to the pressure of wind which is centered in the lower one third of the crown and is conveyed to the lower parts of the stem, increasing with increasing length. To counteract this pressure, which may snap the tree at the base, the tree reinforces itself towards the base. The situation in which tree grows affects the shape and length of the stem. Threes in plains and on ridges in hills have shorter and conspicuously tapering stem. This tapering is due to the wind pressure. On the other hand, the trees growing in the dense forest have relatively longer and more or less cylindrical stem. The production of a long cylindrical bole is a desirable quality in trees because that increases their timber volume.
Buttress, Fluting
In earlier stages, thin branches cover the entire stem but as the sapling grows into poles and trees. The lower branches fall off resulting in a clean bole. But even in later life, sometimes, due to some adverse factors, the clean bole again develops small branches known as epicormic branches. Which is defined as ‘branches originating in clusters from dormant or adventitious buds on the trunk of a tree or on an older branch when exposed to adverse influence such as excessive light, fire or suppression.” They are also caused by drought and that is why they are generally found on stag-headed trees. Buttress: It is outgrowth formed usually vertically above the lateral roots and thus connects the base of the stem with roots. It is formed in Acroccarpus fraxinifolius, Bombax ceiba, Pterocarpus dalbergiodes, Terminalia myriocarpa. Fluting: It is an irregular involution and swelling on the bole just above the basal swell. It is generally in present in teak. As fluting decreases the basal volume considerably, it is considered to be a serious defect. It is attributed to epicormic branches, insect attack, unsuitable site or faulty thinnings.

The Root of Tree

The root is that portion of the plant which develops inside the soil. It is away from the light. Unlike stem it does not produce leaves, flowers or fruits. The roots of trees support them firmly to the ground, absorb soil moisture containing mineral salts and sent it to stem for onward transmission to the leaves. They, generally, comprise of two kinds of roots, viz., The taproot and the lateral roots.

Tap Root

Taproot is the primary descending root formed by the direct prolongation of the radicle of the embryo. In trees, it is the main axis of the large root system. It descends vertically below the stem. The primary root is conical in shape develops towards the permanent moisture in the soil and sometimes, attains considerable length.

Lateral Root

Lateral roots are the roots that arise from the taproot and spread laterally to support the tree. As the taproot grows, it develops lateral roots which are branched and re-branched and ultimately form rootlets. The ends of the rootlets are covered with fine hairs, called the root hairs. All the above-given information about tree is important for tree improvement  

Water Harvesting

Prep Army
-
0
Water Harvesting
The collection and storing of water on the surface of the soil for subsequent use is known as water harvesting. This includes all measures that induce, collect, store and conserve surface runoff in the the region. Water harvesting is most essential operation in arid and semi-arid region, where water is the deficit for most of the season

Methods of Water harvesting

  1. Runoff inducements
  2. Land alteration
  3. Chemical treatments
  4. Runoff farming
  5. Water spreading
  6. Micro catchments
  7. Dug wells
  8.  Tanks
  9. Farm ponds
  10. Percolation tanks
  11. Inter row water harvesting
  12. Broad bed furrows

Rain water harvesting

The rain water harvesting refers to the process of collection and storage of rainwater for specific uses to humankind’s.

Advantages of Rainwater Harvesting

  1. Rainwater is bacteriologically pure
  2. It is free from organic matter and soft in nature.
  3. It will help in reducing the flood hazard.
  4. It will help in reducing the flood hazard.
  5. It improves the quality of existing ground water
  6. Rainwater may be harnessed at place of need and utilized at the time of need.
  7. The structure required is simple, economical and eco-friendly.

Ground Water Recharge

Artifical recharge is the process by which the ground water is augmented at a rate much higher than those under natural condition of replenishment. The techniques of artificial recharge can be broadly categorized :
  1. Direct Recharge
    1. Surface recharge
      1. Flooding
      2. Basins or Percolation tank
      3. Stream augmentation
      4. Ditch and Furrow system
    2. Sub Surface recharge
      1. Recharge Well
      2. Recharge pit
      3. Dug well
  2. Indirect or Induced Recharge

Surface Recharge

These methods are suitable where large area of basin is available and aquifers are an unconfined without impervious layer above it. The rate of infiltration depends on nature of top soil. The various spreading methods are as below:
  1. Flooding: This method is suitable for relatively flat topography. The water is spread as a thin sheet. It requires a system of distribution channel for the supply of water for flooding. Higher rate of vertical infiltration is obtained in areas with undisturbed vegetation and sandy soil covering.
  2. Basin and Percolation tanks: This is the most common method for artificial recharge. IN this method, water is impounded in series of basins or percolation tank. The size of basin may depend upon the topography of area, (flatter area will have large basin). The most effective depth of water in basin is 1.25 m. This method is applicable in alluvial area as well as hard rock formation.
  3. Stream augmentation: Seepage from natural streams is one of the most important sources of ground water recharge. The check dam or widening the steam beds increases the infiltration. In addition, the site selected for check dam should have sufficient permeable layer.
  4. Ditch and furrow system. In areas with irregular topography, ditches or furrow provide maximum water contact area for recharge. This technique requires less soil preparation and is less sensitive to silting.

Sub-Surface Method

  1. Recharge well. Recharge wells can be of two types
    1. Injection well, where water is pumped in for recharge
    2. Recharge well, where water flows under gravity. It is cost effective for shallow water table aquifers up to 50 m. These wells may be of dry or wet types.
  2. Pits and shafts. This is Suitable where impervious layers are encountered at shallow depth. This normal diameter of shaft should be more than 2 m to accommodate more water. A silt free source water can be put into recharge pit directly through pit directly through pipes. In case of silty water, it is suitably filtered through the coarse sand passage before recharging. These structures are cost effective, least evaporative and require less land area.
  3. Dug wells: The dug wells are used as recharge structure by suitably diverting storm water and surplus canal water into it. The water for recharge should be silt free and guided through a pipe to the bottom of well to avoid entrapment of bubbles in the aquifer.

Induced Recharge

It is an indirect method of artificial recharge involving pumping from aquifer hydraulically connected with surface water such as perennial streams, unlined canal or lakes. The heavy pumping lowers the ground water level and zone of depression is created. Lowering of water levels induces the surface water to replenish the ground water. This method is effective where steam bed is connected to aquifer by sandy formation.

Rainfall

Prep Army
-
0
Rainfall

Rainfall

Rainfall is synonymously used with precipitation by many peoples. But these two terms differ typically. Precipitation includes all forms of water that are received by earth from the atmosphere which includes rainfall, snowfall, frost, hail etc. Rainfall generally describes that form of precipitation where the size of water droplets is larger than 0.5mm. Rainfall is termed as light when its intensity is less than 2.5mm/hr, moderate between 2.5 and 7.5mm/hr and heavy when the intensity is more than 7.5mm/hr. Drizzle is a form of rain with numerous droplets of size less than 0.5 mm with intensity less than 1mm/hr. A hailstorm is a form of precipitation in the form of irregular pellets or lumps of frozen rain of size greater than 8 mm. The period with which rainfall occurs is known as the duration of rainfall and is expressed as the unit of time. The intensity of rainfall is defined as the rate at which rainfall takes place. It is expressed in mm/hr or cm/hr. Rainfall intensity decides the runoff. Rainfall frequency denotes the period in years during which a rainfall of a given duration and intensity can be expected to occur. It is expressed as percent chance. Amount of rainfall refers to the depth to which rainwater would stand on a horizontal surface with conditions of no infiltration, runoff, and evaporation.

Types of Rainfall

Orographic precipitation

Orographic precipitation occurs when rain bearing clouds encounter barriers such as mountains. These barriers stop the air and lifted up. This results in the expansion of air and adiabatic cooling. Thus, rain is formed due to the condensation of the water vapor.

Cyclonic precipitation

Cyclonic precipitation refers to the rainfall associated with cyclones. Cyclone is a large whirling mass of air which is moving at a velocity of 50 to 80 km/hr. The low-pressure zone in a cyclone acts as a chimney through which the air mass from surrounding gets lifted up. This causes precipitation heavily.

Convective Precipitation

In Convective precipitation, the air mass is heated up by the solar radiation. The heated air mass become lighter and gets lighted up. THis is followed by adiabatic cooling which causes condensation of water vapour and produces precipitation.

Rainfall Measurement

Rainfall measurement is based on sampling method of estimation. In this method, the rain gauges are located at predetermined points in the watershed and averages value is arrived at. Rain gauges used may be of non recording or recording type. The average rainfall in an area estimated by the following ways. Arithmetic mean: The average rainfall is obtained by dividing the sum of the readings from all the rain gauges in an area by the total number of rain gauges. The distribution of rain gauge determines the accuracy. This method does not give more accurate results due to the irregular duration and intensity of rainfall in the area. R=R1A1+R2A2+R3A3+………+RnAn/A1+A2+A3+…….+An Thiessen polygon Method: The location of the rain gauges is plotted on a map and they are connected by a straight line. Perpendicular bisectors are marked on each of the lines such that each of the rain gauge station is enclosed in a certain area. If R1, R2, R3…. are the amounts of rainfall recorded in each of the rain gauges, average rainfall over the given area (A), is derived from the formula given below: R=R1A1+R2A2+R3A3+………+RnAn/A1+A2+A3+…….+An Isohyetal Method: Rain gauge stations are plotted and located on the map and the amounts of rainfall at each of the station are gathered. Isohyetals (lines of equal rainfall) are drawn by interpolation on the map. The area between the successive Isohyetals is determined, for which planimeter can be used. If P1, P2, P3… are the amounts of rainfall recorded in each of the rain gauge and A1, A2, A3…. are the areas of the irregular figures in between Isohyetals, then the average rainfall (R) could be expressed by the formula given below Isohyetal Method of Precipetition

GENERAL CHARACTERISTICS OF FUNGI

Prep Army
-
0
GENERAL CHARACTERISTICS OF FUNGI
Fungi are eukaryotic, spore bearing, achlorophyllous, heterotrophic organisms that generally reproduce sexually and asexually and whose filamentous, branched somatic structures are typically surrounded by cell walls containing chitin or cellulose or both with many organic molecules and exhibiting absorptive nutrition.

Structure of Fungi

Fungal Thallus / Soma

It is a vegetative or fungal body. Thalli is the plural of the thallus. The Fungal thallus have no chlorophyl at all, and not differentiation into stem, roots, and leaves also lacking the vascular system which differentiates it from plants.

Hypha

The hypha is a thin, transparent, tubular filament filled with protoplasm. It is the unit of a filamentous thallus and grows by apical elongation. Hypha means the web.

Mycelium

Mycelium is a network of hyphae. This network constituting the filamentous thallus of a fungus. Its color depends upon the presence of the pigments in the cell wall. If there is no pigment then it may be colorless. The mycelium may be ectophytic or endophytic.

Types of Fungal Thalli

  1. Plasmodium
  2. Unicellular thallus
  3. Filamentous or multicellular thallus

Plasmodium

Plasmodium is the mass of multi nucleated protoplasm, which is naked and feeding in amoeboid fashion.  Eg. Plasmodiophora brassicae.

Unicellular Thallus

As the name suggest, it is consist of the single celll. Eg.Chytrids, Synchytrium

Filamentous or Multicellular thallus

Majority of fungi i.e., true fungi are filamentous, consisting of a number of branches, a thread like filaments called hyphae. Eg. Many fungi, Alternaria.

Fungi based on reproductive structures:

Holocarpic (holos=whole+karpos=fruit): In this whole thallus is converted into 1 or more reproductive structures, that thallus is called holocarpic thallus. Synchytrium Eucarpic (Eu=good+karpos=fruit): If the thallus is differentiated into two parts in which one part a vegetative part absorbs nutrients and a reproductive part forms reproductive structures, such a thallus is called Eucarpic thallus. Pythium Ectophytic fungus: If the thallus is present on the body surface of the host then it is called ectophytic. Eg. Oidium. Endophytic fungus: If the fungus not present on the body surface but, penetrates into the body of host cell then it is called endophytic. Eg. Puccinia  Endophytic fungus may be inter cellular (hypha grows in between the cells), or intra cellular (hypha penetrates into the host cell).Eg.Ustilago, or vascular (xylem vessels) Eg. Fusarium oxysporum. In the inter cellular fungus penetrate the host cell with the help of a special organs called Haustoria. Haustoria are absent in the intracellular. Endophytic intra cellular mycelium absorbs food directly from protoplasm with out any specialized structures. In ectophytic mycelium, haustoria are produced in epidermal cells.

Septation in Fungi

Fungal hyphae having partitions. Fungus is divided into a number of compartments. These walls are called septa. A hypha with septate is called septate hypha or coenocytic hypha. A hypha without septa is called aseptate or non-septate or coenocytic hypha. the nuclei are embedded in the cytoplasm. Eg. lower fungi like Oomycetes and Zygomycetes. Septa in fungi

General types of septa

Types of Septa based on their formation

Primary septa: Primary septa are formed in direct association with nuclear division (mitotic or meiotic) and are laid down between daughter nuclei separating the nuclei /cells. Eg. Higher fungi like Ascomycotina and Basidiomycotina. Adventitious septa: The Adventitious are formed independent of nuclear division and these are produced to delimit the reproductive structures. Eg. lower fungi like Oomycetes and Zygomycetes in which septa are produced below gametangia (sex organs) which separate them from rest of the cells.

Types of Septa Based on construction:

a) Simple septa: As the name suggests, it is the most common type of septa, it is a plate like, with or without perforation. b) Complex septa: This this type a barrel shaped swelling of septal wall surrounded the septum and covered on both sides by a perforated membrane termed the septal pore cap or parenthesome. Eg. Dolipore septum in Basidiomycotina.

Types of Septa Based on perforation:

a) Complete septa: In this type of A Septum is a solid plate with not a pore or perforations. Eg. Adventitious septa in lower fungi. b) Incomplete septa: In this, A septum contains a central pore.      

Carbon Sequestration

Prep Army
-
0
Carbon Sequestration
Carbon sequestration can be defined as the capture and secure storage of carbon from the atmosphere on a long term basis. In other words, C sequestration can be defined as net removal of atmospheric CO2 into long-lived pools such as terrestrial and oceans by the photosynthetic pathway of plants and micro-organisms. The main objective of the carbon sequestration is to reduce the atmospheric CO2 concentration to reduce the impact of climate change of global warming. The balance between C additions of photosynthetic plant products to the soil and their losses via their subsequent decomposition and microbial respiration determines the amount of organic C present in the soil. Plant residues, manure, sewage sludge, and other organic C by-products are the major sources of C inputs in the terrestrial ecosystem.

Types of Carbon Sequestration

Above ground biomass carbon sequestration

The above ground biomass includes plant, animals, and litter from these. The proportion of carbon stored in these materials varies widely depending upon the species. In general, plants fix the carbon by consumption of CO2 through the photosynthesis mechanism. In this atmospheric carbon is converted in to plant biomass and retained within it until it decays. Woods of trees contain about 25-48 percent by carbon based on its dry weight. So forest has a huge potential in carbon sequestration.

Approaches for above ground biomass carbon sequestration

  • Sustaining the forest cover
  • Decreasing deforestation
  • Regeneration of natural forests
  • Establishing tree plantations and agroforestry.
  • Improving management of agricultural soils and rangelands
  • Improve the fertilizer use efficiency
  • Improving the diet of ruminants

Below ground Carbon Sequestration

Below ground carbon sequestration includes carbon fixation by soil, soil microbes, etc. Carbon stocks in soil exceed the carbon stocks in the vegetation by a factor of two to five. The global soil holds twice as much as the atmosphere (1400-1500 Gt C). The soil carbon pool comprises two components. Soil and vegetation in together exchange 100 GT C per year. In India, the amount of carbon stored in the soil is 23.4-27.1 Gt which is 1.6-1.8% of the global reserve.

Soil Carbon sequestration

It generally refers to the medium and long term (10-15 years) storage of C in the terrestrial soil ecosystem through various physical, chemical biochemical and biological processes in soils. Soils have the capacity to accommodate a substantial amount of C from the atmosphere by photosynthesis and sequester it for a long. The soils have an inherent upper limit or “C saturation level” above which no additional C can be stored. The process controlling saturation limit can be modified and controlled to the soil C sink and the time period over which the soil can be exploited for C sequestration.

Mechanism of Soil carbon Sequestration

Physical Carbon Sequestration

In this soil organic carbon (SOC) is held with soil mineral matrix and aggregates which inhibit microbes accessibility and their enzymes. Secondly, SOC is adsorbed into the clay surfaces which is also not reachable by microbes. The penetration of SOC into interlayer spaces also does the same.

Chemical protection and stabilization mechanisms

In this mechanism, the SOC is converted into a nondegradable carbon material through various chemical processes such as charcoal burning and humification, etc.

Biological protection and stabilization mechanisms

Biological organism improves the soil aggregate formation and hence stabilizes the SOC indirectly. Certain microbial products are highly resistant to the degradation, E.g., Glomalin protein of VAM

Approaches for Soil Carbon Sequestration

  1. Restoration of degraded soils
  2. Improved management of grassland and forest soils
  3. Minimum or conservation tillage
  4. Water conservation
  5. Residue and manure management
  6. Mulching practices
  7. Management for reducing soil erosion

Bioremediation

Prep Army
-
0
Bioremediation

Bioremediation

Bioremediation Definition

Bioremediation is defined as the process where by organic wastes are biologically degraded under controlled conditions to an innocuous state, or to levels below concentration limits established by regulatory authorities. Simply, it is the use of living organisms, primarily microorganisms, to degrade the environmental contaminants into less toxic forms. Bioremediation has its own limitations. Some contaminants, such as chlorinated organic or high aromatic hydrocarbons, are resistant to microbial attack. They are degraded either slowly or not at all. The various microorganisms involved in the biodegradation process is classified as follows.
  1. Aerobic micro organism: Pseudomonas, Sphingomonas, Rhodococcus and Mycobacterium.
  2. The anaerobic microorganism is one which lives in the absence of oxygen.
  3. ligninolytic fungi: Phanaerochaete chrysosporium
  4. Methylotrophs uses methane as carbon and energy.

Factors affecting bioremediation

The existence of a microbial population:

The higher degradation microorganism in the soil encourages better degradation of pollutants in soil.

Availability of contaminants:

it refers to the availability of pollutants to the microbial population. The pollutant in the polluted site should be within the approachable distance. Otherwise, degradation process requires longer time.

Environment Factors

Type of Soil:
Removal of contaminant from clay soil is more cumbersome procedure compared to sandy soil
Temperature:
Moderate temperature favors microbial growth thereby facilitate degradation process. Higher temperature kills the micro organism and low temperature deactivates the enzyme. Hence, these temperatures are not good for degradation process.
Soil Reaction:
Neutral and alkaline reaction favors bacterial population which helps degradation in comparison to the acidic soil reaction which favors fungus population.
Presence of oxygen and nutrients:
Oxygen is essential for respiration and nutrients are essential for the metabolism in microbes. As a result, poor oxygen and nutrient status of soil slow down the degradation process.

Approaches to bioremediation

In situ Bioremediation

In situ techniques are those techniques that are applied to soil and groundwater at the site with minimal disturbance. In-situ biodegradation involves supplying oxygen and nutrients by circulating aqueous solutions through contaminated soils to stimulate naturally occurring bacteria to degrade organic contaminants. It can be used for soil and groundwater. This technique includes conditions such as the infiltration of water containing nutrients and oxygen or other electron acceptors for groundwater treatment. This is the most desirable options due to lower cost and fewer disturbances. It avoids excavation and transport of contaminants.

The bioventing 

The bioventing process involves supplying air and nutrients to contaminated site to stimulate the growth of indigenous bacteria. Bioventing employs low air flow rates and provides oxygen in necessary amounts for the biodegradation while minimizing volatilization and release of contaminants to the atmosphere. It works for simple hydrocarbons and can be used where the contamination is deep under the surface.

Biosparging

Biosparging involves the injection of air under pressure below the water to increase oxygen concentrations and enhance the rate of biological degradation. It increases the mixing in the saturated zone and thereby increases the contact between soil and groundwater.

Bioaugmentation

Bioaugmentation techniques involve the addition of microorganisms that degrade pollutants. It involves both indigenous as well as exogenous microorganisms. Sometimes, exogenous population can’t able to compete with indigenous microbes. In most soils indigenous microorganisms degrades the pollutant effectively under good management.

Ex situ Bioremediation

Ex-situ techniques are those techniques that are applied to soil and groundwater which are removed from the site and dumped elsewhere. The various ex situ measures are described hereunder.
  1. Land farming is a technique which contaminated soil is excavated and spread over a prepared bed and periodically tilled until pollutants are degraded. The goal is to facilitate the aerobic degradation of contaminants. In general, the practice is limited to the treatment of superficial 10-35 cm of soil. It reduces monitoring and maintenance as well as clean-up cost.
  2. Composting technique involves combining of contaminated soil with organic amendments. These organic materials are used as energy source by microbes.
  3. Biopiles are the hybrid farming and composting. In this engineered cells are constructed as aerated composted piles. Biopiles provide a favorable environment for indigenous aerobic and anaerobic microorganisms. It controls the physical losses of the contaminants by leaching and volatilization.
  4. Bioreactors: Bio reactors are used for ex situ treatment of contaminated soil or water. It involves the processing of contaminated solid material or water through an engineered containment system.

Advantages of bioremediation

  1. It is natural process and perceived as an acceptable waste treatment process.
  2. Microbial population sustains naturally using contaminant and decreases pollution.
  3. The output residues are harmless products (Carbon dioxide or CO2, water, and cell biomass).
  4. It is useful for complete destruction of wide variety of contaminants.
  5. This process transforms the hazardous compounds into harmless products.
  6. The complete destruction of target pollutants is possible.
  7. Bioremediation can be carried out without disrupting normal activities.
  8. The potential threats to human health and the environment are less
  9. Bioremediation is less expensive.

Disadvantages of Bioremediation

  1. 1. Bioremediation is often highly specific and limited to biodegradable compounds
  2. In some cases, the end products may be more persistent or toxic than the parent compound.
  3. The presence of metabolically capable microbial populations, environmental conditions, and levels of nutrients determines the extent of degradation which is normally not controllable.
  4. It is difficult to extrapolate pilot scale studies to full-scale field operations.
  5. Research is needed to develop bioremediation technologies for different sites.
  6. Bioremediation takes longer time than other treatment.
  7. It requires pretreatment such as excavation, washing or physical extraction before being placed in a bioreactor.
Types of Forest Phytoremediation

Phytoremediation

Prep Army
-
0
Phytoremediation

Phytoremediation

Phytoremediation Definition

Phytoremediation is an emerging bioremediation technology that uses the plant to remove contaminants from soil and water. It designates all vegetation based remediation measures. A plant has a potential for accumulating, immobilizing, and transforming a low level of persistent contaminants. In natural ecosystems, plants act as filters and metabolize hazardous substances.

Types of phytoremediation

Phytoextraction or Phytoaccumulation

Phytoextraction or phytoaccumulation is the process whereby the plants accumulate contaminants into the roots and shoots. This technique saves cost by accumulating low levels of contaminants from a widespread area.

Phytotransformation or Phytodegradation

Phytotransformation or phytodegradation refers to the uptake of organic contaminants from soil, sediments, or water and, subsequently, their transformation to more stable, less toxic, or less mobile form. Metal chromium can be reduced from hexavalent to trivalent chromium, which is a less mobile and non-carcinogenic form.

Phytostabilization

Phytostabilization is a technique in which plants reduce the mobility of contaminant and migration of pollutants in contaminated soil. Leachable constituents are adsorbed and bound into the plant’s structure so that they form a stable mass of plant.

Phytodegradation or Rhizodegradation

Phytodegradation or rhizodegradation is the breakdown of contaminants through rhizosphere activity. This activity is due to the presence of proteins and enzymes produced by the plants or by soil organisms such as bacteria, yeast, and fungi.

Rhizofiltration

Rhizofiltration is a water remediation technique that involves the uptake of contaminants by plant roots. Rhizofiltration is used to reduce contamination in natural wetlands and estuary areas

Phyto volatilization

Phytovolatilization is to the uptake and transpiration of soil, water or plant contaminants, by plants. The contaminant, present in the water taken up by the plant, passes through the plant or is modified by the plant, and is released to the atmosphere (evaporates or vaporizes). Also Read: Bioremediation

Types of Forests

Prep Army
-
0
Types of Forests

Types of Forests

Forests types are ‘category of forest defined concerning its geographical location, climatic and edaphic features, composition and condition.’ Champion and Seth define it as ‘a unit of vegetation which possesses (broad) characteristics in physiognomy and structure sufficiently pronounced to permit of its differentiation from other such groups. This is irrespective of physiographic, edaphic or biotic factors. It is selected in the first place subjectively from the ever-varying cover of vegetation, with boundaries arbitrarily imposed on what are in fact gradual changes.

Object of classification (Forest types)

The primary objective of classification of forests into forest types is to find out correct silvicultural techniques and management practices for development of the woods. These methods and practices cannot have universal application because forests vary from place to place. Therefore it becomes necessary to classify the forests into forests types, so that suitable silvicultural techniques and management practices may be evolved for each kind to be applied to similar classes in the field.

Bases of Classification

The forests classified into forest types by

Types of forest by Physiognomy

Physiognomy means the general appearance of forest community and, therefore, forms a smooth basis for rough differentiation of extensive classes. Dominant growth form describes it (e.g., trees, shrubs, grasses, etc.), the seasonal changes (e.g., evergreen and deciduous habit) and such other features as may be associated with very dry or very wet sites.

By Structure

Structure of a forest is described by stratification (i.e., the way in which different species are aligned in various layers of the forest) and dimensions of trees including height and spacing. It is observed that more favorable site to tree growth the higher is the number of strata and the less desirable the location, the lesser is the number of levels in which the forest is divided. Therefore, structure stratification gives the excellent basis for classifying forest types.

Types by Function

Function refers to the most common morphological characters of the species such as leaf characters, leaf size, stem and root characters, e.g., buttress formation, development of stilt roots, etc., which form the basis of classification.

By Floristics

Floristics refers to the species present in a particular forest. While this forms an essential foundation for delimiting a forest type, there is a significant difference of opinion as to whether the frequency of the species should be used as a basis or not. However, this can be used to distinguish subtypes.

On the basis of Dynamics

As a result of interaction between vegetation and the site, there is continual change between the two. This results in succession and development of climate communities. Though the general view favors Whittaker’s theory of vegetational gradients, it is convenient for the time being to classify the relatively stable types as a climax, those still developing as seral, the stable community resulting from the particular soil peculiarities as the edaphic climax and that resulting from the biotic interference as a biotic climax.

Habitat

Habitat refers to the effective environmental conditions in which a forest community exists. Thus, climate and edaphic factors often form the basis of classifying forest vegetation.

According to Physiography

Physiography refers to the natural features of the earth surface. As it modifies the microclimate and results in different vegetation occurring in the same climate on various aspects of the hill slope, it forms a reasonable basis for classifying vegetation.

Types of forest by History

History refers to past biotic influences on a site and its vegetation. Though these are very important in determining the present condition and future potentialities in vegetational communities, it often difficult to assess these factors correctly.

System of classification

The environment has the most profound influence on vegetation which not only grows and develops in its context but remains in equilibrium with it. Therefore, the system of classification of plant can be either; i) Botanical, i.e., based mainly on vegetation ii) climatic, i.e., based primarily on climate iii) Ecological, i.e., based mainly on ecosystem consisting of vegetation-environment complex.

Classification based mainly on vegetation

The Classification based primarily on vegetation is made by the study of plant communities. This system of classification considers vegetation presence, its structure, composition, dynamics, etc. E.g., Fosberg and Webb classification of forests

Climatic Classification of Forests

This classification is mainly based on the temperature in association with or without other factors. e.g., Schimper classification, Koppen classification, Paterson classification and Thornthwaite classification.

Ecological Classification of Forest

This system considers climate and vegetation. This is most widely accepted one, e.g., Gaussian Classification, Champion and Seth classification.

According to the WWF major types of forest are

  1. Tropical Forest
  2. Sub-tropical Forest
  3. Temperate Forest
  4. Mediterranean
  5. Coniferous Forest
  6. Montane Forest

Types of Forest in India

  1. Tropical Wet Evergreen Forest
  2. Tropical Semi-evergreen forests
  3. Tropical moist deciduous Forest
  4. Littoral and Swamp forest
  5. Tropical dry deciduous forest
  6. Tropical Thorn Forest
  7. Tropical dry evergreen forest
  8. Subtropical broad leaved hill forest
  9. Subtropical pine forest
  10. Subtropical dry evergreen forest
  11. Montane wet temperate forest
  12. Himalayan moist temperate forest
  13. Himalayan dry temperate forest
  14. Subalpine forest
  15. Moist alpine
  16. Dry alpine scrub
Also, Read Forest management Deforestation

Deforestation

Prep Army
-
0
Deforestation
Deforestation is the removal of tree or forest cover from a particular land without the intention of reforesting. After the Industrial Revolution the deforestation rate increase to meet the local demands. There are many effects of deforestation, some are (hydrologically, economically, environmentally, biodiversity). But the deforestation in the Amazon forest is the main concern of today.

Causes of Deforestation

The main causes of deforestation or reasons for deforestation are
  1. Clearing of forest land for agriculture
In the beginning, human beings lived in the forests and when they began to take up settled agriculture small gaps were cleared for raising food crops. Gradually as the population grew the demand for land went up and more and more forest areas were cleared for agriculture. This continued unabated for several centuries and the forest cover shrunk drastically. 2. River Valley projects Hundreds of river valley multipurpose projects have been taken up after the industrial revolution for transportation and other purposes. These projects also to generate electricity, provide water for irrigation and prevent floods. However, in spite of the immense benefits of the projects, they cause deforestation in the following ways :
  • Loss of forest due to submergence under the reservoir
  • Loss of forest land due to construction of approach roads, housing colonies for staff and labor, godowns and other miscellaneous purposes
  • Loss of forest land for rehabilitating people displaced as a result of these projects
The provision of compensatory afforestation has come in for criticism as environmentalists feel that the natural ecosystem lost cannot be created elsewhere particularly with respect to the biological diversity. The major part of rain forest is in the Amazon forest which leads to rainforest deforestation. 3. Settlements Almost all human settlements of today including towns and cities were once forests. Clearing of forest for human settlements continued till the beginning of this century after which the pace slowed down considerably. However, even in recent times, forests have been cleared for human settlements and industrial complexes without the provision for compensatory afforestation. 4. Roads and rail lines Road and rail lines are usually laid after clearing forests. This has been a standard practice since earliest times and even today forest land is used for the construction of roads and rail lines. In the hilly areas a fairly large forest area has to be diverted for roads as the forest area is relatively more and besides the actual area for road a much larger area is destroyed as hill road involve cutting of the slopes. Moreover the debris of road construction is thrown in forests lying downhill of the construction site. 5. Electric lines High powered electric transmission lines are taken over forest area as a result of which all vegetation has to be cleared beneath them. This is another cause of deforestation, particularly in the hills. 6. Other developmental works Forest area is cleared for other developmental works such as
  • Canal and irrigation channels
  • Fruit belts in the hills
  • Schools and colleges
  • tanks and small reservoirs

Factors favoring the Deforestation of forest land

A number of favor the diversion of forest land for non-forestry purposes. These are a) Easy availability: Forest land is easily and readily available particularly in the period before the enactment of the Forest Conservation Act of 1980 (INDIA). In cases where non-forest land is selected for developmental works, its acquisition and payment of compensation is a lengthy process. Considerable litigation in courts may be involved and this takes quite some time. This easy availability of Forest land also leads to the deforestation. On the other hand, forest land belongs to the state which is initiating the developmental project and it is easy to get this land. Use of forest and also keeps down the cost and time required for completion of the project. The procedure involved in the use of forest land is less cumbersome even if the exemption has to be taken under the Forest Conservation. b) Lack of awareness: There is a general lack amongst planners and the general public about.
  • The importance of forests
  • The role played by then in our economy
  • Need to conserve forests
  • The protective influence of forests
  • Complexity of forest ecosystem, the destruction of which will cause an irreversible loss
  • Role of forests in the everyday lives of the tribals and people living in rural area.
It is this lack and perception that results in forest becoming the easiest land for any purpose be it a river valley project, road or any other developmental scheme. c) Low productivity: Forests have low productivity in commercial terms. As matter of fact, for long forests were termed as unproductive jungles. The protective functions of forests were realised by planners only a few decades back d) Lack of economic appreciation: For a long time only the direct economic benefits of forests were taken into account with no emphasis being laid on the indirect economic benefits such as meeting the fuel and fodder needs of the teeming millions and also benefits such as carbon sequestering. There are many bad impact of deforestation, so we need deforestation solutions earlier before we lost everything. For more also Read lecture notes on Forest Management
1...101112...21Page 11 of 21