In which stage of cell division crossing over takes place?

Answer. Pachytene stage.

What is plant growth hormone? Describe different types of plant hormones.

A plant growth hormone is a specific chemical substance produced in one part of a plant and transported to other parts which control the growth and some other functions of the plant. Plant hormones are also known as growth regulators or growth substances.


                          According to Thimann (1948-52), a hormone may be defined as " an organic substance produced naturally in higher plants,controlling growth or other physiological functions at a site remote from its place of production and active in minute amounts."

                   
Following are some major plant hormones:

1. AUXIN :

The name auxin was given to the growth hormone produced by the tip of coleoptile. Kogl and Haagen-Smit (1931) first discovered the active principle of this growth hormone which has been termed as auxin-a. The chemical identification of it shows that this substance is a nitrogen free compound known as auxenotriolic acid. Shortly afterwards, Kogl  et al (1934), isolated another compound, auxenolonic acid which they termed as auxin-b. Both auxin-a and auxin-b are light and heat stable and can be easily oxidised.

        In the same year Kogl et al discovered the third substance which they named as hetero-auxin whose chemical nature has been proved to be 3- indole acetic acid or IAA.

         Besides IAA, a number of naturally occurring auxins have been identified racently.

Different physiological effects of Auxins:


(A) ON GROWTH:
The most characteristic effect of auxin is to promote growth by cell enlargement. The action of auxin in controlling growth appears to be a complex of many functions.

(B)  ORGAN DIFFERENTIATION:
 Auxins and other plant hormones not only affect the growth by elongation, but also affect the morphological type of growth. Thus by applying auxins, a young stem may develop cluster of cells differentiated into callus roots, vegetative buds and sometimes even flowers.

(C) FRUIT DEVELOPMENT:
 The role of auxin in the normal process of fruit set has been thoroughly investigated by Gustafson (1936). This discovery of fruit set by auxin treatment has a great value in commercial practice, in producing fruit set when natural set is difficult.

2. GIBBERELLINS: 

(A)DORMANCY AND SEED GERMINATION:
 The gibberellins are involved in the phenomena of dormancy, flowering and fruiting. In many plants dormancy can be broken with gibberellins.

(B) SEX EXPRESSION:
Gibberellins have a definite role in the sex expression of Cucurbitaceae (Mitchell and Wittwer, 1962). Gibberellins causes formation of male flowers whereas, low concentration of gibberellins favours the formation of female flowers.

(C) PARTHENOCARPIC FRUIT-SET:
Gibberellins also induce parthenocarpic fruit-set in a number of plants and such fruits are usually seedless.

3. CYTOKININS: 

Cytokinins cause changes in the protein and nucleic acid components of tissues which are the basis of the cytokinins effects on cell division (Guttaman, 1956) as well as growth and mobilization actions. Cytokinins bring about the mobilization of various solutes including amino acids, auxins, and phosphorus.

What is algae? What are the general characters of algae?

Algae (singular: alga) is a group of photosynthetic organisms which are mostly found to grow in aquatic conditions. Algae may  grow  in fresh water,  salt water or in moist areas. their body is very simple as the body of an alga usually can not be divided into roots, stem and leaves. More than 20,000 different species of algae have been identified till today.

                                                       Fig: Algae growing in water body.

General characters of algae:

1. Algae may be eukaryotic, unicellular or multicellular.

2. They are autotrophic due to the presence of chlorophyll.

3. Their cell wall is made up of cellulose.

4. Some members of algae are filamentous.

                                                            Fig:  Algae in moist place.


5. They can reproduce by means of fragmentation, asexual reproduction or sexual reproduction.

6. Some examples of  algae are: Chara, Chlorella, Ectocarpus, Chlamydomonas ect.

What is hydroponics?

          Hydroponics is a technique of growing plants in nutrient solution.Hydroponics is a kind of modern farming practice that basically deals with producing crops without soil. In this farming practice the farmer do not requires any land for farming.This technique was first developed by a German botanist called Julius Von Sachs in the year 1860.

      In this process plants are grown in large tanks containing nutrient solution and are supported by water netting. Tanks are provided with all the facilities and under control environment.This process has got great success and at present many countries of the world like United States of America, Isreal, Abu Dhabi etc. use this system in commercial basis. It is also useful in tropics,where water is less and in places where soils are not fertile.

Advantages of Hydroponics:

1. Less labour cost.

2. Easy to control the pests.

3. Less cost to produce crops.

4. Possible to produce more crops is less space.

5. One can perform this practice in highly populated area like city also to full fill his interest and desire.

6. Less water requirement.

7. High profitable.

8. More control over environmental issues.

Disadvantages of Hydroponics:

1. It requires a high infrastructure cost at a time.

2. Requirement of skilled and knowledgeable person to perform this practice.

3. Can not grow trees. Only vegetables can be grown in this method of cultivation.

Difference between cell wall and cell membrane

CELL WALL :

1. The cell wall is the outermost boundary membrane of plant cells.
2. It is thick, rigid and non-living.
3. The cell wall is compost of three layers namely middle lamella, primary wall and the secondary wall.
4. Cell wall is permeable.
5. It is not involve in the formation of cell organelles.
6. The cell wall does not perform endocytosis.

CELL MEMBRANE :

1. The cell membrane is the outermost boundary of animal cell but in plant cells it lies beneath the cell wall.
2. Is is thin, delicate and living in nature.
3. The cell membrane is also consists of three layers- The outer and inner protein layers between which an another layer which is known as lipid layer as the layer is compost of lipid.
4. Cell membrane is semi-permiable in nature.
5. Cell membrane helps in the formation of covering membrane of cell organelles.
6. It performs endocytosis.

Biological classification and its advantages

Biological classification and its advantages

There are thousands of different types of living organisms in this planet called Earth. Therefore, it is simply not possible to study all the organisms one by one. To overcome this problem, it is necessary to develop a process by which an organism's taxonomic position in the living world can be easily ascertained. This process is called classification.

Classification can be simply defined as the method of grouping or arranging the living organisms in different groups based on their similarities and dissimilarities.

Importance of biological classification

Biological classification plays a great role in studying the living organisms in an effective and scientific way. Classification helps us to study the organisms easily and even rapidly. Classification makes the taxonomic study easier, as the characters of a particular group would apply to all the individuals of that group.

Advantages of classification

The grouping of organisms following a definite plan is very useful for proper study in the following way-

• It is possible to know about all the organisms but the study of a few representatives from each group will enable to have a broad idea of the life as a whole.
• It recognizes and describes the basic taxonomic units or species.
• It makes the study convenient.
• It facilitates identification of organisms.
• It reveals relationship among the various groups of organism.
• It also enables the biologists to interpret the poorly visible structures of fossils.

Scope, importance and application of biology.

This age may be termed as 'age of biology'. Like physics, chemistry and computer science, biology has also a great important role in the development of human civilization. People use the knowledge of biological science in different purposes. the importance of biological sciences can be discussed under the following heads:

INDUSTRY:

There are many industries which are completely or partially based on different biological products such as dairy industry, fermentation industry, biogas production industry, leather industry etc.

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BIOTECHNOLOGY:

Biotechnology is a branch of biology which has a great impact on modern agriculture, different industries which are mainly based on biological products and, commerce. Biotechnology can be used to get virus free plants, new variety of plants etc. Biotechnologists are now busy to evolve new type of bacteria by which unwanted materials of environment can be destroyed.

WAR AGAINST DISEASE:

There are a lot of microorganisms in the atmosphere which can cause different diseases. The knowledge of biology can save us from those diseases and illness. The discovery of antibiotics like penicillin, streptomycin, chloromycetin, tetramycin etc. are effective against almost the entire range of bacterial diseases and have cut down deaths due to septic wounds to a negligible number. with the development of different vaccines, we have been able to virtually eradicate small-pox, and diseases like diptheria, whooping cough,tetanus, measles, tuberculosis,polio,mumps etc. At present the scientists are trying to develop vaccine against the killer disease AIDS with the help of the knowledge of genetic engineering.

POPULATION CONTROL:

The success of the knowledge of medical science has resulted in the mortality rate which created the problem of over population. Due to the sharp declination of death from different diseases, there has been a rapid growth in the world population. Different birth control measures are used to control the explosion of population which has started showing positive result. The knowledge of biology is highly essential for effective control of human population.

BIOLOGY AND EUGENESIS:

Eugenesis deals with the genetic improvement of human race be genetic counselling. Gradual elimination of defective genes from human race through marriage is the main thrust of eugenesis.

FOR FOOD PRODUCTION:

The unlimited population explosion has created demands of food. We must look into the ways by which we can produce more food and which can be achieved only by using the knowledge of biological science.The application of modern techniques and knowledge of biology have great contribution to enhance our food production. Knowledge of poultry, fishery, dairy, piggery, have helped us a lot for the continuous supply of meat, fish, milk, and different milk products.

POPULATION GROWTH CURVE

           Introduction

• Population growth curve is something that shows the pattern of the growth of a population over  time  i.e., a growth curve is an empirical model of the evolution of a quantity  over  time. 

• Growth curves are widely used in biology for quantities such as population size or  biomass , individual body height or biomass. Values for  the measured property can be  plotted on a graph as a function of time.

• In theory , any kind of  organism could take over  the Earth just by reproducing.

•  But in practical, all living  organisms need some specific resources such as nutrients and proper environmental conditions to survive and reproduce.

• The essential resources are not unlimited, and a population can only reach a size that match the availability of resources in its local environment.

TYPES OF POPULATION GROWTH CURVES

 There are mainly two types of population growth curves-

     1. Exponential growth curve( J-shaped)

                                  &

    

      2. Sigmoid growth curve(S-shaped)

EXPONENTIAL GROWTH CURVE

• —  In this type of growth form, the population grows exponentially, and after attaining the peak value the population may abruptly crash.

• This increase in population is continued till large amount of food materials exist in the habitat.

• — After sometime, due to increase in population size the food supply in the habitat becomes limited which ultimately results in decrease in population size.

• For example, many insect populations show explosive increase in numbers during the rainy season, followed by their disappearance at the end of the season.

• The following equation exhibits J-shaped growth:

             dN/dt = rN                                             

                                         

             where,   

                                    

            dN/dt represents rate of change in population.

             r=biotic potential

             N= population size 

SIGMOID GROWTH CURVE 

      

• The sigmoid growth curve is also known as Logistics growth curve which is S-shaped.           

• When a few organisms are introduced in an area, the population increase is very slow in the beginning i,e., the positive acceleration phase or lag phase.            

• In the middle phase the population increase becomes very rapid which is known as logarithmic phase.     

• Finally in the last phase the population increase is slowed down i,e. negative acceleration phase.

 —           

• The level beyond which no major increase can occur is referred to as saturation level or carrying capacity which is denoted by K.—            

• In the last phase the new organisms are almost equal to the number of dying individuals and thus there is no more increase in the population size.         

• The J-shaped (sigmoid) growth form is represented by the following equation:

         dN/dt = rN(K-N/K)                   

                   =rN(1-N/K)

                     Here,

                    dN/dt is the rate of change in population size.

                     r= biotic potential

                     N= population size

                    (K-N/K) is for environmental resistance.

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CARRYING CAPACITY

                                    

— 

• The carrying capacity of a biological species in an environment is the maximum population size of the species that the environment can sustain indefinitely , given the food , habitat , water and other necessities available in the environment.

• — In population ecology, the carrying capacity is defined as the environment’s maximal load.

•  Carrying capacity was originally used to determine the number  of  animals that could graze on a segment of land without destroying it. Later the idea has been expanded to more complex populations.

biologican nitrogen fixation

biological niotrogen fixation

A comparative study of two organic fertilizers: Vermicompost and self prepared green algal fertilizer on the growth efficiency of Capsicum annuum (Bell papper).

                                                         INTRODUCTION

Capsicum annuum Gr.  :

•       Capsicum annuum Gr. (also known as sweet pepper , pepper, bell pepper or capsicum) belongs to the family Solanaceae , originated in Central and South America.

•       Sweet pepper has a firm fruit wall and a leathery peel

•       The fruit contains a kidney- shaped , white core to which the seeds are attached.

•       The plant produce fruits in different colors, including red, yellow, orange, green and purple.

    Soil:

•       soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life.

•       There are three main types of soil: sand, silt and clay.

•       The best soil for most plants for optimum growth is a rich sandy loam. Loam  is  an even mixture of the three main types of soil.

•    With the time the natural fertility of the soil is declining and thus fertilizers are used to counter the nutrient deficiency of the soil.

 Fertilizers:

•   A  fertilizer is any material of natural or synthetic origin that is applied to soils or to plant tissues to supply one or more plant nutrients essential for the growth of  plants.

•   Fertilizers are inputs which enhanced the growth, development and overall characteristics of the planting crop.

•   Blue green Algae in recent times gained tremendous importance as organic fertilizer but, there is very scanty of literature regarding the use of green algae as organic fertilizer.

•   Keeping this in view, following objectives were proposed for the study:

      Objectives:

1.  To collect green algal mat  from Killing village(Ri-bhoi district) and  identify  the composition of the mat.

                                         

2. To prepare  fertilizer from the green algae  collected from different streams of the area.

To study the effect and comparison of two different organic fertilizers , vermicompost  and self prepared green algal fertilizer on the growth efficiency of Capsicum annuum Gr.                                  MATHODS AND MATERIALS

                                               

1.STUDY SITE:

 The study site, Botanical garden, University of Science and Technology, Ri-bhoi  district of Meghalaya lies in between 90 ̊55’15 to 91 ̊16’ latitude and 25 ̊40’ to  25 ̊21’ longitude.

2.Climate:

The temperature ranges from 10̊C in December to 30̊C in the month of July and August.

3. Physico-chemical characteristics of soil and water of the study site:

physical characteristics of soil was studied. NPK was estimated from soil and algae by Kjeldal method.

4. Preparation of plot and planting methods:                                                               

 Ploughing , and removal of debris materials.Sufficient amount of surface soil from the ploughed area was taken in 30 different pots.  Little water was  introduced in each  of the pots     and then plantlets  of 42 days were transplanted in the pots, one in each pot. Then the pots  were arranged in three different rows equally – one for no treatment   (control),   one for  vermicompost treatment and the another one is for self prepared green algal treatment.

 5. Physical parameters and biochemical properties:

       The physical parameters such as the plant height, no.of branches, leaves , number of flowers,  leaf areas  were recorded after every 7 alternative days.The biochemical properties such as  the chlorophyll a, b and carotenoid was worked out by Arnon method (1949).                                                                                                                                                                                                                                                                      

      Capsicum annuum on the first day of transplant(35^th day)     

                                                                                                                                                                                                                                                                                                                                         Manures and fertilizers      

The use of  fertilizers  and manures enhance the growth and effect of the physiological and morphological characteristics of the plant depending upon the type of fertilizers and the concentration used. The fertilizers used for the study includes:

                    1. Organic fertilizer

 Vermicompost:  Vermicompost is the product of the compost excreta of Earthworm. The process of producing vermicompost is known as vermi-composting.

                     2.  Algal fertilizer  

                                                     

Algal dry biomass is known to contain  rich source of macro and micro nutrients, which in  turn can be used by plants for their growth . All the essentiality of the dry biomass can thus contribute to the development of the planting crop in small or large scale. 

PREPARATION OF ALGAL FERTILIZER

    The steps involved in the preparation of algal fertilizer are as follows-

                            

1.  Green algal mat were collected  and washed thoroughly to remove the debris of unwanted soil and waste particles.

2. The algal mass was taken to the laboratory for taxonomic identification and preparation of algal fertilizer.

3. Selected strain of  algae were rinsed free of sand and debris with the help of tap water and put over the glass slide, covered up by cover slip.

4. The strain was then observed under a light microscope and identified following different monographs of Tiffany (1952).

5. After identification, the algal masses were then sun dried till it become brittle and crackling firm.

  6.  The sundried algae were crushed and grinded with the help of electronic grinder.                                                                                                                                                                                                                                                                                                                                                  

   7.The powdery masses of the green algae are now measured as per requirement and a paste was        prepared adding the green algal powder in an 1000ml beaker with 500ml distilled water.

        

        8.   Then the beaker was kept for 48 hours in the laboratory at room temperature so that the                        nutrient content of the green algae comes to simple form.

                                                           

         9.   After 48 hours   the algal fertilizer was applied in crop concerned.

                                        

          APPLICATION OF FERTILIZERS

                                                                                             

1. Any  fertilizer was not applied in the plants of first row.

2.  15 gm vermicompost per plant of second row was applied after every 7 alternative days .

3.  2 gm self prepared green algal fertilizer (Spirogyra)  per plant of third row was applied after every 7 alternative days. 

     RESULTS

      NKP estimated amount in dry algae- Spirogyra sp.

Sl.. No	Element	Amount (mg/kg)
1	N	0.68
2	P	2.9
3	K	8.3

        

 The physico-chemical characteristics of the soil

    The Ri-bhoi soils are rich in organic carbon, the ranges of the nutrients also varies as shown in the following table.

    Table.2: Physico-chemical properties of the surface soil (0-15cm depth)-

                                                                                

particulars	Percentage content	Methods of determination
A.   Mechanical composition          1.Sand          2. Silt                                        3. Clay   Textural classification	77              22               1          Loamy sand	Hydrometer
Chemical composition             Soil pH                Available                              nutrients(kg/ha)          a. Nitrogen(N2)          b. Phosphorous(P2O2)           c. Potassium(K2O)	6.3             1247.94            448.84             929.38	Digital pH meter.                  Kjeldahl method

                                   

          Summary and Conclusion

1.    From the above results it is clear  that the green algal fertilizer have    relatively greater influenced on the physical parameters of plant such as plant height, number of leaves, leaves area, early flowering, no . of flowers, no. of branches no. of fruits and seeds than the vermicompost.

2.    Therefore. It can be concluded that  self prepared algal fertilizer can be used as a successful organic fertilizer which can give faster and better yield.

3.    Moreover, as  algal mats were collected from eutrophicated streams for preparation of fertilizer, so in turn it can be a technique to remove  eutrophication from streams and utilize the same for successful organic farming.

4.    As Spirogyra in this region is a very common alga which grows in many streams and ponds . Flourishing utilization of this alga can be a boon to clear eutrophication and at the same time accelerate organic farming.

5.     In future days, large scale production  of fruits and vegetables can be done by using this organic  green algal  fertilizer.