Author Archives: chavda chetan

Stem:

Stem is a part of plant which lies above from surface of soil i.e. it shows negative geotrophic growth. It has nodes and internodes. Branches, leaf, flower bud and bract are developed from nodes. Stem arises from plumule.

It normally has leaves, branches and flowers. Young stem is green in colour and performs Photosynthesis. The growing apex of the stem bears number of tiny leaves which protect them. The branches and leaves develop exogenously on stem, which develops into nodes and internodes

Node and Internode: The swalen part place of stem or branch from where leaves arise is known as node, and the space between two successive nodes is called internode. Leaf and branches develop from the node. Node may be easily distinguished in some plants eg. sugarcane, bamboo or may not have clear marks.

Bud: Bud can be defined as “young underdeveloped shoot consisting of a short stem number of tender leaves arching over the growing apex. In buds the internodes are not developed and the leaves cover the apex forming a compact structure. Leaves at the lower side of the buds are larger and at the upper side are small. (acropetal succession)

Buds are of two types i.e. floral buds from which flower develops and vegetative buds from which stem and leaves develops. When the stem or branch ends with vegetative bud it continues to grow. If floral bud is at the end of the stem the growth of stem ceases.

On the basses of the position buds can be classified into four categories

(a) Terminal bud : it grow the terminal position on the apex of the stem or branch which continuos to grow in upward direction.

(c) Accessory bud (6usest): It grows on the node but slightly away from the axil of the stem giving rise to the lateral branches

(d) adventitious buds

Buds arising on stem, leaf on roots are adventitious buds

Function of stem :

Bearing leaves and flower: Flowers and leaves are on branches and stem. Stem spreads them in all direction so that leaf gets enough sunlight and flowers can attract the insects for pollination and reproduction.

Conduction (Transportation): The stem transports water and minerals from the root to all parts of the plant and transport nutrition from leaf to all parts of the plant, especially to storage organ and growing region.

Support: The main stem acts as a supporting pillar for branches, which spreads in all direction.

Storage: Stem also acts as a storehouse of food material, especially in case of ginger, potato onion etc.

Food manufacture: Young stems, green in colour contains chlorophyll which manufactures food in the presence of sunlight.

Life history of Mucor

CLASSIFICATION

Division. – mycota

Sub-Division. – Eumycotina

Class. – zygomycates

Order. – mucorales

Family. – mucoraceae

INTRODUCTION

Mucor, the most common member of the Mucoracene, has more than 100 species. It is saprophytic fungus.

OCCURRENCE

Mucor is found throughout the world. Out of 100 species 17 species of Mucor are found in India. Some Indian species are Mucor hiemalis, Mucor indicus, Mucor mucedo, Mucar praine.Most of the species of Mucorare saprophytic on a variety of materials including foodstuffs rich in sugar and starch. In damp conditions they spoil organic materials such as bread, jams, jellies, over ripe fruits, syrups, etc. Mucor emits a musty smell and honce it is called Muss (foul-smell). It is also found on leather. Some species of Mucor are coprophilous (dung-inhabiting) and few are strictly terrestrial Mucor mucedo and Mucor racemosus are common air contaminants.

Mucor also grows well on moist bread. Thus, it is commonly known as bread mould. It can be grown in laboratory by placing bread slices in a moist chamber at room temperature. The fungus appears in the form of white cottony or woolly growth within 2-3 days. This is also called pin muuld or blackmould because of its black spores.

Species of Mucor are known to cause mucoromycosis in domestic animals d

and human beings. It infect organ like lungs, brain etc, which may cause even death of the organism.Many species of Mucor are responsible for causing rotting of fruits and vegetables. Some species of Mucor, g, Mucor javanicus are used industrially for alcoholic fermentation.

VEGETATIVE STRUCTURE

Mucor is haploid plant. The thallus of Mucor consists of highly branched course coenocytic mycelium which forms white, grey or brownish cottony growth on the substratum. It appears as a loose fluffy mass of cotton. Mycelium differentiated into aerial and prostrate hyphae. The branches of mycelium are usually tapering to fine points. The prostrate hyphae serve as function of absorption and sometime serve as fixative. Young hyphae are without septa but they appear in older hyphae, when reproductive structures are developed.

In annerobic liquid cultures, especially in the presence of carbon dioxide, the hyphae break to form yeast-like bodies. This state of fungus is referred to as torula condition. If oxygen is made available it reverts to filamentous stage.

Hyphae consist of cell wall, plasma-membrane and protoplasm. The wall of hyphae is made up of chitin mycofibrils and chitosan. Besides these, polysaccharides, proteins, lipids, purines, pyrimidines and a few minerals (calcium, Magnesium etc.,) are also present in the cell wall.The cell wall is lines internally by a thin plasma-membrane which encloses the protoplasm. The cytoplasm is granular and contains numerous vacuoles of small size. Numerous nuciai are present and are distributed all over the cytoplasm. The food reserve is in the form of glycogen and oil droplets.

Life history of Sargassum:

Classification

Division – phaeophyceae

Class. – cyclospore

Order. – fucales

Family. – sargassaceae

Genus. – sargassum

INTRODUCTION

There are about 150 species in this genus.

OCCURRENCE

The marine alga is popularly called gulf weed. It is found chiefly in the tropical and subtropical seas of southern hemisphere. Most of the species attached along the rocky shores. They are especially abundant in the warmer sons, Some species along the Indian coast (East and West) and that of the Australian sens and also in Japan. The Sargassum natans and Sargassum fluitans are abundantly found in the Atlantic oceans around the gulf of Mexico. Hence this part of Atlantic Ocean is called the Sargasso sea. It lies off the African coast between 20 and 35 North latitude. In India the genus is represented by 16 species which occur along the Western and Southern coast. Some common species of Sargassum are S. einereum, S. carpophyllum, S. duplicatum, S. christifolium, S. tenerrium, S. ilicifolium, S. plagiophyllum, S. wightii and S. myrioeystum.

THALLUS STRUCTURE

The Sargassum plant is macroscopic and more or less hushy in habitat. Apparently like a small angiospermic plant. The plant body is radially symmetrical. Some species such as S. vulgare and S. filipendula are found attached to the substratum. Free floating unattached forms like S. natans is very common. It occurs in huge floating masses.

EXTERNAL STRUCTURE

The thallus of Sargassum in diploid and sporophytic. It is erect and branched and is differentiated into holdfast and the main axis. It benars many leaves like lateral branches andair bladders latter on.

Life history of Spirogyra

CLASSIFICATION

Division- chlorophyta

Class. – chorophyceae

Order. – zygnematales

Family. – zygnemataceae

Genus. – spirogyra

INTRODUCTION

It is one of the commonest of green filamentous algae abundant in spring. It includes about 289 species and of these 94 has been reported from India. They are universal distribution but are relatively rare in the tropics. Of this various species S. condensata is commonly met with.

Occurrence

It is found in bright green, free-floating masses in the fresh water. It is found growing abundantly in fresh water ponds, pools, lakes, ditches, and also in slow flowing streams. In some species growing in running water, a short unicellular organ of attachment, called hapteron is formed. Spirogyra adnata is an attached form and found in flowing waters. Because of the slippery feel of the threads Spirogyra is often called the Pond-scum or Water silk. S. maxima, S, longata and S. nitido are some of the common species.

Thallus structure

It is thallus which consists of a long green cylindrical thread about 1/10 mm across and several centimetres long, filament. Each spirogyra plant possess filamentous structure. The filamentous are unbranched. Normally the filaments are free living, free floating and slimy and each consists of a few hundred similar cylindrical cella placed end to ond in a single row. There is no basa! distal differentiation, S. adnata and S. jogensis however, are exceptions. The basal coll in these species functions as an attaching organ. It developa rhizoidal outgrowths which assist in attaching the filament to the substratum. S. rhizopus and S rhizobrachialis, S. dubia and S. affinis also have rhizoids.

CELL STRUCTURE

The cell comprising the filament is cylindrical in form with transverso end walls. They are usually much longer than hroad. The cell has the structure typical of aparenchymatous cell. It consists of two parts, the cell wall and the protoplast

Cell wall

It surrounds the protoplast and thus forms its boundary. It is protective in function. The Cell wall is made up of two layers. The inner layer is cellulose in nature. It forms complete envelops around the protoplast. However, external layer envelops an inner layer which is the pectose layer. The outermost portion of pectos changes into pectin. The latter dissolves in water to form a slimy sheath. This mucilage sheath is sometimes referred to as the third layer of the cell wall it makes the filament feel slippery to touch. Because of the slippery feel of the thronds Spirogyra is often called the Pond – seum or Water silk.

Protoplast

The protoplast is differentiated into plasms membrane, cytoplast, one or more chloroplast with pyrenoids and a large central

The plasma membrane surrounds the cytoplast. The outer cytoplast forms a thin lining or a peripheral layer in contact with cell wall. It is also encloses a large central vacuole filled with cell sap, known as inner cytoplast. Inner cytoplast is often rich in tannins and other organic and inorganic compounds in solution. The sap vacuole is separated from the surrounding cytoplast by a thin, semipermeable membrane, the tonoplast. Embedded in the cytoplast and parietal in position are the large conspicuous chloroplast. They vary in number in different species from one to as many as fifteen in each cell.

Each chloroplast is an elongated, green helical band lying against the wall (parietal). It runs in a spiral manner and anticlockwise direction from one end of the cell to other. Because of Spiral chloroplast fenture the genus known as Spirogyra. All the chloroplast in the cell may be loosely or tightly coiled and run spirally in parallel. The band-shaped chloroplast or ribbon shaped chloroplast possess series of small, spherical, rounded bodies known as Pyrenoids. They lies equidistance from one another.

Algae in human welfare:

Importance of algae has not much realized by a layman but a deep study of the subject shows immense value to human beings. Algae show harmful as well as wedel ellect to human being and environment. Useful aspects of algae are as

(1) Algae as food:

The alge are important source of food of the fishes, aquatic amphibian. mammale and other animals. Algae are rich in carbohydrates, many inorganic and organic compounds, proteitis, vitamins, etc. Thus, it is used as food. Some costal part of the world used it as food.

Man’s dependence on fish and other aquatic animals to supplement his die Indirectly, therefore the algae are great value to man. Several preparations of algae are used in various countries, Ulva lactuca is used in or the preparation of saled and soups in Scotland.

Chlorella is high producers of lipids and proteins, thus useful in space flights and submarine as food.

Among Rhodophyceae (red nigae) the genera commonly used as food

Chandrus (carragern or Irish moss), Porphyra, Rhodymenia, otc. In species Porkyra, vitamins C and B12 are found in sufficient quantities. The colonies of Nostor commune are boiled and are used as food in Chit and Java. In our country few species of Spirogyra and Oedogonium are utilised as food in South india

(2) Algae in industry

Many products of commercial and pharmaceutical importance have be derived from algae. Agar, carrageenan, alginate and diatomite are some important commercial products of algae origin.

Agar is obtained commercially from species of Gelidium, Pterocladin Gracilaria, Acanthopeltis, Chondrus and Gigartina, Japan and South East Asia are the main production centres of agar. The greatest use of agar is in food pharmaceutical and cosmetic industry. It is used in manufacture of processed cheese, puddings, creams and jellies. In preservation and canning of fish and meat, it is used as gelling and thickening agent. Pharmaceutically agar is used as laxative. It is an important constituent of cosmetics (ointments, lotions etc). It is used for almost a century as stiffening agent in culture media.

Carrageenan is obtained from the cell wall of Chondrus crispus and Gigartina stellata. It is used in stabilization of emulsions in paints and cosmetics In alcohol and sugar industry it is used as a clearing agent. It is also utilized in the textiles, leather and brewing industries. It is also used as stabilizing agent in ice creams, chocolates, cosmetics, tooth pastes, etc.

Alginate is salts of alginic acid which occur in cell wall of brown algat belonging to order Laminariales. It is extracted from Laminaria, Fueus, and Macrocystis etc. Alginate is non-toxic and viscous and readily forms gel, hence useful us thickner (in soup, sauce, cream, and printing ink), emulsifier (in ice cream, polish) and gelling agent (in confectionery and dental impression powder). Alginit acid stops bleeding effectively. Flame poof fabrics are also prepared from it.

Diatomite is a deposit of dead frustules or cell walls of fossil dintoms (Bacillariophyceae). The walls of diatoms have a heavy deposit of silicon dioxide (SiO). When the diatoms, which form a major part of planktons, die the remains of the cell wall are deposited at the bottom of the water reservoirs. These deposits are called diatomaceous earth. It is used as insulating agent in boilers, steam pipos, furnaces, etc., where the temperature rises to about 100° F.It is used in car polishes, silver polishes and tooth pastes It is an absorbent for nitro-glycerint. hence used in the transport of dynamite Diatomite is also useful in oil refineries for filtration process. It is useful in the preparation of paint, varnishes, abrasives. glass and porcelain. It is also used as a filter for battery boxes.

(3) Algas as source of minerals:

Brown alene are rich in soda, potash, iodine and alginic acid. Ash of dry kelps is a source of enda, which is used in manufacture of soap, glassware and alum. Seaweeds are very rich in minerals and form the commercial source of their extraction Kelps, the members of Laminariales of Phaeophyceae (Ascophyllum, Echilonia, Laminaria,etc.) were the chief source of iodine extraction in Europe. Brumine is extracted from members of Rhodophyceae like Polysiphonia, Rhodymenio, ste. Many important minerals like copper, iron, zinc, cobalt, vanadium, manganese and boron are present in high proportion of seaweeds.

(4) Algae as source of Vitamins:

The marine algae are the richest source of vitamins. The vitamins A, B and E are found abundantly in sea weeds. The vitamin B essentially required for the development of human body is found in great abundance in almost all Phaeophyceae. The cod liver oil is rich source of vitamin A, which is acquired from seaweeds

(5) Algae as Manure:

In France, Iceland Scotland and Norway, members of Phaeophyceae (brown algae) like Fucus, Macrocystis, Sargassum, etc., are used as manure. Many useful inorganic minerals are obtained from them.

(6) Algae in nitrogen fixation or as bio fertilizer:

Blue-green algae (Cyanophyceae), ‘viz, Aulosira, Anabaena, Nostoc, etc., fix elemental nitrogen and thus increase the soil fertility. These algae have special cells called heterocyst which are the sites for nitrogen fixation. Fairly good yield of rice can be obtained over a number of years without addition of any nitrogenous fertilizer because of the presence of nitrogen fixing blue-green algae in the rice fields.

(7) Reclamation of alkaline usar soils by blue – green algae:

Saline Usar’ soils of north India could be reclaimed by growing blue green algae, like Nostoc, Anabaena, Scytonema, etc. The algae increase the mineral content of the soil and thus the crop yield.

(8) Larvicidal properties of algae:

Blue-green algae like Aulosira and Anabaena, and green algae like Chara and Nitella eliminate mosquito larvae from ponds and pools in which they grow.

(9) Alga as antibiotics:

Many algae as Chlorella, Cladophora, Polysiphonia and Laminaria synthesize antibiotic substances. The first such antibiotics chlorellin was obtained from Chlorella. Ascophyllum is effective against gram positive and gram negativebacteria. Alsidium and Codium are effective vermifuge. Some algae are used in treatment of disease of kidney, urinary bladder and lungs.

(10) In sewage disposal:

Water borne domestic and industrial waste is called sewage. It contains Organic and inorganic material in soluble and for suspended form. Although disposal of sewage is mostly an aerobic process, sewage is usually poor in oxygen. It is necessary to treat sewage nerobically before disposal because (1) it anaerobic digestion produces unpleasant odour, and (ii) it is a rich source of many inorganic nutrients like sulphur, nitrogen, potassium and phosphorus as such properly treated sewage can serve as fertilizer.

The sewage disposal is an acrobic process and production of oxygen from algal photosynthesis, helps it. Algae like Chlorella, Chlamydomonas, Scenedesmus, Pediastrum, Euglena, Oscillatoria, etc., can grow in these rich organic wastes and provide oxygen to aerobic bacteria. Hence, an oxidation pond is an example of algal bacterial symbiosis.

(11) Algae as medicines:

Several diseases caused by vitamin deficiency such as vitex, asthma, tooth decay etc., may be eradicated. If flour of the sea weeds is added to the food, it can help to cure thyroid gland related disease. It is very rich source of vitamins and minerals, thus it is good source of it. Gelidium is useful in stomach disorder.

(12) Algae as experimental Material in biological research:

Algne have always been a useful material for conducting physiological and genetic experiments since these can be easily grown and manipulated. Chlorella and Scenedesmus (green algae) have been used extensively for studying photosynthesis. Acetabularia, a green alga was used to establish hereditary role of nucleus. Halicystis, Valonia, etc.. (green algas) are useful in the studies on permeability.

(13) Manufacture of light weight buildings:

Germany has discovered a process, in which the sea weds are mixed in cement to make buildings light in weight and good heat resistant.

(14) Ornamental Uses:

Some algae like Botrydium and Spirogyra are grown in the garden ponds for their good looking habit.

Definition

The study of rate of chemical reaction and related mechanism known as chemical kinetics or

The study of change in concentration with time for chemical reaction is known as chemical kinetics.

Rate of reaction.

In unique time increase or decrease in concentration of reactant and product is known as rate of reaction.

Therefore in unique time concentration of reactant decrease and concentration of product increase.

It depends on

– concentration of reactant, temperature, presence of catalyst, nature of solvent.