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State dehiscence of anther
Posted by Bikram Singh (Aug 19, 2017 4:40 p.m.) (Question ID: 13539)

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  • Anther dehiscence - Dehiscence is the splitting at maturity along a built-in line of weakness in a plant structure in order to release its contents, and is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part.

    Answered by Sahdev Sharma (Aug 19, 2017 6:15 p.m.)
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Why do we say there is no natural death in single celled organisms ?
Posted by Abhay Singh (Aug 19, 2017 3:46 p.m.) (Question ID: 13502)

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What is Chromosomal Theory of Inheritance??
Posted by Sahana Roy (Aug 19, 2017 2:21 p.m.) (Question ID: 13454)

  • Kindly explain the same process during cell division...
    Posted by Sahana Roy (Aug 19, 2017 3:07 p.m.)
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  • Chromosomes are Inherited From Your Parents. One chromosome from each of your 23 pairs came from each of your parents. The two chromosomes of a pair (except for the sex chromosomes) contain the same genes, but the genes have small differences.

    Answered by Arun Soni (Aug 19, 2017 2:56 p.m.)
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Plz help me to understand Law of Independent Assortment....
Posted by Sahana Roy (Aug 19, 2017 2:19 p.m.) (Question ID: 13452)

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Mechanism of translation
Posted by Paalki Manocha (Aug 19, 2017 2:08 p.m.) (Question ID: 13443)

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State the function of filliform apparatus found in mature embryo sac of an angiosperms
Posted by Ravi Maurya (Aug 19, 2017 11:53 a.m.) (Question ID: 13388)

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  • Function of filiform apparatus is

    • To Stimulate division of generative
    •  Produce nectar
    • Guide entry of pollen tube
    • Recognize the suitable pollen at stigma
    Answered by Sahdev Sharma (Aug 19, 2017 12:14 p.m.)
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Nitrogen cycle
Posted by Beena Choudhary (Aug 19, 2017 5:57 a.m.) (Question ID: 13270)

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  • The continuous sequence of events by which atmospheric nitrogen and nitrogenous compounds in the soil are converted, as by nitrification and nitrogen fixation, into substances that can be utilized by green plants, the substances returning to the air and soil as a result of the decay of the plants and denitrification.

    Answered by Soumya Ghoshal (Aug 19, 2017 7:21 a.m.)
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What is periplasmodial tapetum
Posted by Bikram Singh (Aug 19, 2017 12:17 a.m.) (Question ID: 13254)

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  • The tapetum is a specialised layer of nutritive cells found within the sporangium, particularly within the anther, of flowering plants, where it is located between the sporangenous tissue and the anther wall.[1]

    Tapetum is important for the nutrition and development of pollen grains, as well as a source of precursors for the pollen coat.[2] The cells are usually bigger and normally have more than one nucleus per cell. As the sporogenous cells undergo mitosis, the nuclei of tapetal cells also divide. Sometimes, this mitosis is not normal due to which many cells of mature tapetum become multinucleate. Sometimes polyploidy and polyteny can also be seen. The unusually large nuclear constitution of the tapetum helps it in providing nutrients and regulatory molecules to the forming pollen grains. The following processes are responsible for this:

    • Endomitosis
    • Normal mitosis not followed by cytokinesis
    • Formation of restitution nuclei
    • Endoreduplication

    Tapetum helps in pollenwall formation, transportation of nutrients to inner side of anther, synthesis of callase enzyme for separation of microspore tetrads.

    Types of tapetum
    Two main tapetum types are recognised, secretory (Glandular) and plasmodial (amoeboid). In the secretory type a layer of tapetal cells remains around the anther locule, while in the plasmodial type the tapetal cell walls dissolve and their protoplasts fuse to form a multinucleate plasmodium. A third, less common, type the invasive non-syncytial tapetum has been described in Canna, where the tapetal cell walls break down to invade the anther locule but do not fuse to form a plasmodium.

    Amongst the monocots Acorales, the first branching clade has a secretory tapetum, while the other alismatid clade, Alismatales are predominantly plasmodial. Amongst the late branching clades, the lilioid monocots are nearly all secretory while the commelinid monocots are diverse with respect to tapetal pattern.

    Answered by Himanshu Singhal (Aug 19, 2017 8:53 a.m.)
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A bilobed, dithecous anther has 100 microspore mother cells per microsporangium.how many male gametophytes this anther can produce??
Posted by Dolly Janu (Aug 18, 2017 11:22 p.m.) (Question ID: 13241)

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There are 20 chromosome in the shoot tip cells of maize plant. What is the number of chromosome in the microscope mother cells of same plant?
Posted by Dolly Janu (Aug 18, 2017 11:20 p.m.) (Question ID: 13237)

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Lockjsj
Posted by Akash Kumar (Aug 18, 2017 10:54 p.m.) (Question ID: 13221)

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Which book is best for doing practice of board paper
Posted by Charu Chauhan (Aug 18, 2017 9:54 p.m.) (Question ID: 13168)

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Explain replication
Posted by Ujjawal Sharma (Aug 18, 2017 7:17 p.m.) (Question ID: 12944)

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  • In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. This process occurs in all living organisms and is the basis for biological inheritance. The cell possesses the distinctive property of division, which makes replication of DNA essential.

    DNA is made up of a double helix of two complementary strands. During replication, these strands are separated. Each strand of the original DNA molecule then serves as a template for the production of its counterpart, a process referred to as semiconservative replication. Cellular proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication.

    In a cell, DNA replication begins at specific locations, or origins of replication, in the genome. The unwinding of DNA at the origin and synthesis of new strands results in replication forks growing bi-directionally from the origin. A number of proteins are associated with the replication fork to help in the initiation and continuation of DNA synthesis. Most prominently, DNA polymerase synthesizes the new strands by adding nucleotides that complement each (template) strand. DNA replication occurs during the S-stage of interphase.

    DNA replication can also be performed in vitro (artificially, outside a cell). DNA polymerases isolated from cells and artificial DNA primers can be used to initiate DNA synthesis at known sequences in a template DNA molecule. The polymerase chain reaction (PCR), a common laboratory technique, cyclically applies such artificial synthesis to amplify a specific target DNA fragment from a pool of DNA.

    Answered by Arun Soni (Aug 18, 2017 7:23 p.m.)
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What is NPP
Posted by Beena Choudhary (Aug 18, 2017 7:10 p.m.) (Question ID: 12938)

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  • Hi Beena,

    NPP is Net Primary Productivity.

    To understand that, you first have to understand Primary Productivity which is, - The amount of biomass or organic matter produced per unit area over a time period in plants during photosynthesis. It expressed in terms of weight (gm-2) or energy (kcal m-2).

    It is of two types :

    GPP and NPP

    Gross Primary Productivity: It is the rate of production of organic matter during photosynthesis in an ecosystem. It is utilized by plants for respiration and some are passed to the next trophic level. 

    Net Primary Productivity: It is the weight of the organic matter stored by the producers in a unit area/volume per unit time. It is utilized by Heterotrophs.

    NPP = GPP - R  (R = Respiration losses)

    Answered by Anurag Chauhan (Aug 18, 2017 7:35 p.m.)
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  • Net Primary Productivity (NPP) is the amount of carbon uptake after subtracting Plant Respiration (RES) from Gross Primary Productivity (GPP). GPP is the total rate at which the ecosystem capture and store carbon as plant biomass, for a given length of time.

    Answered by Arun Soni (Aug 18, 2017 7:28 p.m.)
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Difference between active and passive immunity ?
Posted by Abhishek Mishra (Aug 18, 2017 7:01 p.m.) (Question ID: 12924)

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  • Active immunity involves your bodies direct response to an unknown pathogen. This response is the production of antibodies specific to the antigen of a particular pathogen. This type of immunity is not immediate as it takes the time to have create enough of the correct antibodies to fight the pathogen. However, the response lasts for a long period of time and in some cases, where antibodies remain in the body as memory cells, immunity to the specific pathogen may be life long.

    Passive immunity is an immune response which involves antibodies obtained from outside the body. An example of this is the antibodies a mother passes to her infant through her breast milk. Immunity to the pathogens which these antibodies are specific to is therefore immediate, as no time is needed to create them. However, this immunity is not long term and may only last a few days.

    Answered by Arun Soni (Aug 18, 2017 7:11 p.m.)
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Ovoviviparous
Posted by Shweta Kumari (Aug 18, 2017 8:08 a.m.) (Question ID: 12672)

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  • Animal producing young by means of eggs which are hatched within the body of the parent, as in some snakes.

    Answered by Dr Pathikrt Banerjee (Aug 18, 2017 9:42 a.m.)
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What is the sintific name of tonato
Posted by Dolly Janu (Aug 17, 2017 11:05 p.m.) (Question ID: 12587)

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  • Solanum lycopersicum

    Answered by Arun Soni (Aug 18, 2017 4:01 a.m.)
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WHAT IS ROLE OF ALLES HOW IT iS DIFFERENT FROM GENE??
Posted by Saharsh Tak (Aug 17, 2017 9:57 p.m.) (Question ID: 12523)

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  • A gene is a stretch of DNA that determines a certain trait. Genes mutate and can take two or more alternative forms; an allele is one of these forms of a gene.

    An allele is found at a fixed spot on a chromosome. Chromosomes occur in pairs so organisms have two alleles for each gene — one allele in each chromosome in the pair. Since each chromosome in the pair comes from a different parent, organisms inherit one allele from each parent for each gene. The two alleles inherited from parents may be same (homozygous) or different (heterozygotes).

    For example, the gene for eye color has several variations (alleles) such as an allele for blue eye color or an allele for brown eyes.

    Another important difference between the two is that alleles occur in pairs. They are also differentiated into recessive and dominant categories. Genes do not have any such differentiation.

    So, A gene is a part of the DNA. Alleles, on the other hand, refer to different versions or types (like blue, brown etc.) of the same gene.

    Answered by Anurag Chauhan (Aug 18, 2017 9:08 p.m.)
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Working of lac operon
Posted by Abhishek Singh (Aug 17, 2017 8:59 p.m.) (Question ID: 12425)

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What is condom and how to use it
Posted by Deepak Kumar (Aug 17, 2017 6:48 p.m.) (Question ID: 12248)

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  • Condoms are barriers made of thin rubber/latex sheath used to cover the penis in male or vagina and cervix in the females. It prevents the deposition of ejaculated semen into the vagina of the female.

    Answered by Anurag Chauhan (Aug 18, 2017 9:14 p.m.)
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What is apiculture? And how is it important in our live
Posted by Ansh Sharma (Aug 17, 2017 5:41 p.m.) (Question ID: 12207)

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  • Apiculture is the practice of bee-keeping for the production of various products such as honey, bee’s wax, etc.

    Honey is a highly nutritious food source and is used as an indigenous system of medicines. It is useful in the treatment of many disorders such as cold, flu, and dysentery. Other commercial products obtained from honey bees include bee’s wax and bee pollen. Bee’s wax is used for making cosmetics, polishes, and is even used in several medicinal preparations. Therefore, to meet the increasing demand of honey, people have started practicing bee-keeping on a large scale. It has become an income generating activity for farmers since it requires a low investment and is labour intensive

    Answered by Himanshu Singhal (Aug 17, 2017 6:59 p.m.)
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What is plant breeding
Posted by Ansh Sharma (Aug 17, 2017 5:37 p.m.) (Question ID: 12205)

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  • Plant breeding is the process by which humans change the characteristics of plants over time to make them better crops and more nourishing food.
    In its most simple form, breeding consists of selecting the best plants in a given field, growing them to full seed and then using that seed to grow further generations.
    Such selective breeding changes the genetic composition of the plants over time.
    The most important factor for plant breeding is genetic variation in the desired characteristic.
    For example, a farmer who wants to select a plant with resistance to an insect pest will watch for the plants that survive an insect attack. Another farmer wanting larger fruits will save seeds from plants yielding the biggest fruits in the field.
    The most important factor for basic selective breeding is to start with plenty of genetic variation and to select and multiply the characteristic of interest. 
    As a result from breeding, most of the species we rely on for food are very different from their wild relatives.
     

    Answered by Himanshu Singhal (Aug 17, 2017 7:06 p.m.)
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Meaning of lever
Posted by Md Squib Ajaz (Aug 17, 2017 4:23 p.m.) (Question ID: 12151)

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why DNA is mostly stable??
Posted by Manisha Kumari (Aug 17, 2017 4:02 p.m.) (Question ID: 12135)

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  • The main bonding in DNA which renders the double helix structure is so stable because of the hydrogen bonds. Between the complementary base pairs, hydrogen bonds connect the two strands of the helix. There are 3 H bonds between Guanine and Cytosine and 2 between Adenine and Thymine. As well as this there are hydrogen bonds between the bases and surrounding water molecules, and this combined with the even stronger phosphodiester bonds in the sugar phosphate backbone make DNA very stable.  

    Answered by Anurag Chauhan (Aug 18, 2017 8:47 p.m.)
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Use of cyclosporin A
Posted by Indu Dhar (Aug 16, 2017 9:04 p.m.) (Question ID: 11827)

  • Sofidi
    Posted by Nitin Raj (Aug 16, 2017 9:22 p.m.)
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  • cyclosporin A is an immuno suppressant; ie, it supresses your immune system. This is administered intravenously or through an oral dose and is mainly required in case of organ transplants to prevent rejection of the foreign tissue. 

    Answered by Neera Agarwal (Aug 17, 2017 4:08 p.m.)
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What is multiple allele
Posted by Sri Sharma (Aug 16, 2017 8:50 p.m.) (Question ID: 11797)

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    Posted by Sri Sharma (Aug 17, 2017 5:33 a.m.)
  • Multiple allele are those which controll one charachter by more than 2 gene
    Posted by Utkarsh Gupta (Aug 16, 2017 9:30 p.m.)
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  • Usuall, 1 gene has 2 alleles. on e dominant,and other is recessive. (eg:  Aa). But in some cases, Like in human blood groups, the character(blood group) is controlled by more than 2 alleles (which in human blood group are Ia, Ib and i). this is called multiple Allelism.

    Answered by Neera Agarwal (Aug 17, 2017 4:12 p.m.)
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biology means?
Posted by Soman Mohapatra (Aug 16, 2017 8:36 p.m.) (Question ID: 11762)

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  • simply, study of living organisms. including their anatomy,morphology, physiology.

    Answered by Neera Agarwal (Aug 17, 2017 4:13 p.m.)
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What is transpiration
Posted by Samreen Saifi (Aug 16, 2017 8:28 p.m.) (Question ID: 11741)

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  • Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers 

    Answered by Poulami Dasgupta (Aug 16, 2017 8:42 p.m.)
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human insulin diagram.

Posted by Pihu Oraon (Aug 16, 2017 7:34 p.m.) (Question ID: 11657)

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All papaya plants bear flowers but fruits are seen only in some. Why?
Posted by Drishti Baruah (Aug 16, 2017 6:46 p.m.) (Question ID: 11620)

  • Because some bear only male flower
    Posted by Utkarsh Gupta (Aug 16, 2017 9:31 p.m.)
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  • Which plants consists female flower they are tranfer into the fruits only.

    Answered by Soumya Ghoshal (Aug 16, 2017 7:50 p.m.)
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