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    • Posted by Gurjobanpreet Singh Bhullar 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Meghna Thapar 6 years, 1 month ago

    DNA fingerprinting is a method of identifying the DNA by locating the differences in the arrangement of nucleotides in those specific regions of the DNA sequence which are repeated several times. The technique is called DNA typing or DNA profiling. DNA fingerprinting involves identifying differences in the repetitive DNA sequences. The repetitive DNA is called satellite DNA. Variation in satellite DNA is very useful in establishing the identity of victims from blood stains, semen stains, hair roots, tears or saliva and in solving paternity disputes. Steps of DNA Fingerprinting: (i) Isolation of DNA. (ii) Digestion of DNA by restriction endonucleases. (iii) Separation of DNA fragments by electrophoresis. (iv) Transferring (blotting) of separated DNA fragments to synthetic membranes, such as nitrocellulose or nylon. (v) Hybridisation using labelled VNTR probe. (vi) Detection of hybridised DNA fragments by autoradiography. Applications of DNA fingerprinting: i. It helps in identification of criminals or potential suspects and relieving people wrongly accused of crimes. ii. It is used to infer blood relationships in the members of the same family. iii. It is used to determine to the real parents of a given offspring. iv. It is used to determine the actual parents in case of a lost child. v. It is used to determine the *** of badly damaged bodies of accident victims or of archaeological specimens.

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    • Posted by Sneha George 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Lily ☺ 6 years, 2 months ago

    S ince the DNA is enclosed within the m embranes, we have to break the cell open to release DNA along with othe r macromolecules such as RNA, proteins, polysaccharides and also lipids . This can be achieved by treating the bacterial cells/plant or animal tissue with enzymes such as lysozyme (bacteria), cellulase (plant cells), chitinase (fungus). DNA that separates out can be removed by spooling You know that genes are located on long molecules of DNA interwined with proteins such as histones. The RNA can b e removed by treatment with ribonuclease whereas proteins can b e removed by treatment with proteas e. Other molecules can be removed by appropriate treatments and purified DNA ultimately precipitates out after the addition of chilled ethanol. This can be seen as collection of fine threads in the suspension

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    • Posted by Sabari R 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Meghna Thapar 6 years, 1 month ago

    (i) Origin of replication: It is the start point where DNA replication begins at a specific point where intertwined DNA segments start unwinding. In prokaryotic cells, there is a single origin of replication, whereas in eukaryotic cells, there are numerous origins which merge during replication. (ii) Unwinding of two DNA strands: It takes place in the presence of helicases which unwind the helix and topoisomerases which break and reseal one strand of DNA. Unwinding of DNA leads to the formation of a Y-shaped structure of the two strands of the DNA duplex. This is known as the replication fork. (iii) Synthesis of primer: It is a stretch of RNA formed on the DNA where synthesis of new DNA starts. The DNA-directed RNA polymerase synthesises the primer strands of RNA for leading and lagging strands. New strands grow from the fork, and as replication proceeds, it appears as if the point of divergence at the fork is moving. (iv) Synthesis of leading (continuous) strand: The synthesis of the continuous strand (new) of DNA is formed in the 5′–3′ direction on the 3′–5′ DNA template because of the addition of deoxyribonucleotides at the 3′ end of primer RNA. This process occurs in the presence of DNA polymerase and ATP. One new strand is formed in a continuous stretch in the 5′–3′ direction and is called the leading strand. (v) Formation of lagging (discontinuous) stand: In the second parental strand, the enzyme primase forms the RNA primer. The enzyme DNA polymerase synthesises the DNA in the form of short stretches once again in the 5′–3′ direction starting from a RNA primer. These short DNA segments, consisting of numerous nucleotides, are called Okazaki fragments. The Okazaki short segments are joined by the enzyme DNS ligase. This newly synthesised second DNA strand is called the lagging strand because it is formed later on in reference to the first continuous strand.

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    • Posted by Shivam Saxena 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Muskaan Vig 6 years, 2 months ago

    Haldane and Oparin experiment. It says that all lofe forms arose from inorganic molecules .They even proved it experimentally.this theory is most accepted because all of us has dna

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    • Posted by Ravi Ahirwar 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Yogita Ingle 6 years, 2 months ago

    Complementary genes are the genes which are present on different genetic loci but interact with each other to express a single character in combination. That is they both together produce a particular phenotypic trait in an individual.

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    • Posted by Sahil Rajput 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 0 answers
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    • Posted by Paridhi Singh 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 2 answers

    Pragati Chaudhary 6 years, 2 months ago

    Active immunity -it develops due to contact with pathogens It has few side effects It takes time to develop its response Eg.-vaccination for polio Passive immunity - It develops when ready-made antibodies are injected into the body It may cause a problem It is used when the immune response has to be faster Eg-antibodies in colostrum

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    Sanju## M.. 6 years, 2 months ago

    In Active immunity the antibodies are produced by the body as well as introduction of microbes either any infection induces active immunity it is slow but it takes long time and has no side effects In passive immunity thr antibodies are directly given to yhe body as wellas no introduction of microbes takes place . It is fast but lasts only few days ....

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    • Posted by Abhay Kumar 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 0 answers
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    • Posted by Arya Khan 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 0 answers
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    • Posted by Harry Shergill 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 3 answers

    Dinesh Kumar 6 years, 2 months ago

    AUG IS A START CODON & UAA IS A STOP CODON ....WHICH OCCURS IN A TRANSLATION TO FORM PROTEINS BY tRNA

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    Muskaan Vig 6 years, 2 months ago

    AUG is start codon UAA is stop codon

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    Ayush Pandey 6 years, 2 months ago

    Stop codons

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    • Posted by Pankaj Giri 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Meghna Thapar 5 years, 8 months ago

    The geologic time scale (GTS) is a system of chronological dating that relates geological strata (stratigraphy) to time. It is used by geologists, palaeontologists, and other Earth scientists to describe the timing and relationships of events that have occurred during Earth's history. The evolution of modern humans from our hominid ancestor is commonly considered as having involved four major steps: evolving terrestriality, bipedalism, a large brain (encephalization) and civilization.

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    • Posted by Paridhi Singh 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Yogita Ingle 6 years, 2 months ago

    – Confirms if abnormality is present in fetus that may have been detected from other tests, such as blood tests.

    – Offers a specific diagnosis of chromosomal or genetic abnormality prior to birth of child.

    – Diagnosis of other hereditary defects depending on family history.

    – Allows early preparation for child with birth defect or early decision making as to carrying the baby to full term.

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    • Posted by Paridhi Singh 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 0 answers
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    • Posted by Kaif Khan 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 3 answers

    Muskaan Vig 6 years, 2 months ago

    Welcome?

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    Kaif Khan 6 years, 2 months ago

    Thank you

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    Muskaan Vig 6 years, 2 months ago

    Third trophic level Explanation:plants are at first trophic level Herbivores at second eg cow Human at third as u eat curd made from milk of cow

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    • Posted by Ishan Mishra 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Yogita Ingle 6 years, 2 months ago

    From a medical perspective, cancer types can be classified based on the type of cell it originated from. Therefore cancer can be classified into:

    Carcinoma

    The most common form of cancer, it originates from the epithelial cells

    Sarcoma

    Originates from the connective tissues such as cartilage, fat and bone tissues.

    Melanoma

    Originates from melanocytes, which are a type of cell that contains pigments.

    Lymphoma & Leukaemia

    Originates from the cells that comprise blood (such as b lymphocytes or white blood cells)

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    • Posted by Anju Phuyel 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Meghna Thapar 6 years, 1 month ago

    Biofertilizers are the substance that contains microbes, which helps in promoting the growth of plants, trees by increasing the supply of essential nutrients to the plants. It comprises living organisms which include mycorrhizal fungi, blue-green algae, and bacteria. Mycorrhizal fungi preferentially withdraw minerals from organic matter for the plant whereas cyanobacteria are characterized by the property of nitrogen fixation. Nitrogen fixation is defined as a process of converting the di-nitrogen molecules into nitrogen compounds. For instance, some bacteria convert insoluble forms of soil phosphorus into soluble forms. As a result, phosphorus will be available for plants. Types of Biofertilizers: Following are the important types of biofertilizers: Symbiotic Nitrogen Fixing Bacteria Rhizobium is one of the vital symbiotic nitrogen-fixing bacteria. Here bacteria seek shelter and obtain food from plants. In return, they help by providing fixed nitrogen to the plants. Loose Association of Nitrogen-Fixing Bacteria Azospirillum is a nitrogen-fixing bacteria that live around the roots of higher plants but do not develop an intimate relationship with plants. It is often termed as rhizosphere association as this bacteria collect plant exudate and the same is used as a food by them. This process is termed as associative mutualism. Symbiotic Nitrogen-Fixing Cyanobacteria Blue-Green algae or Cyanobacteria from the symbiotic association with several plants. Liverworts, cycad roots, fern, and lichens are some of the Nitrogen-fixing cyanobacteria. Anabaena is found at the leaf cavities of the fern. It is responsible for nitrogen fixation. The fern plants decay and release the same for utilization of the rice plants. Azolla pinnate is a fern that resides in rice plants but they do not regulate the growth of the plant. Free-Living Nitrogen-Fixing Bacteria They are free-living soil bacteria which perform nitrogen fixation. They are saprotrophic anaerobes such as Clostridium, Beijerinckii, Azotobacter, and Bacillus polymyxin. Among all the types of biofertilizers, Rhizobium and Azospirillum are most widely used.

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    • Posted by Ashiq Ashiq 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Yogita Ingle 6 years, 2 months ago

    Chorion is one of the membranes that exist during pregnancy between the developing foetus and the mother. Chorionic villi are finger-like projections that arise from the trophoblast layer that develops in the zygote after it has undergone implantation.

    Functions of chorion:

    • Chorionic villi interdigitates with projections from uterine tissue to form a structure called the placenta, which is the connecting link between the mother and the foetus.
    • It facilitates the supply of oxygen and nutrients to the embryo

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    • Posted by Pratyaksh Anil Lutare 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 2 answers

    Alisha Jajodia 6 years, 2 months ago

    Dna polymerase,ori,helicase,ssbp,ligase,topoisomerse,

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    Ayush Ahlawat 6 years, 2 months ago

    Ligase,topoismerase,helicase,DNA dependent DNA polymerase

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    • Posted by Nancy Bagoria 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 2 answers

    Nancy Bagoria 6 years, 2 months ago

    I want to know about blastocyst development in fallopian tube means ectopic pregnancy

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    Ayush Ahlawat 6 years, 2 months ago

    It provide the suitable environment for fertilisation

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    • Posted by Saba Elias 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 0 answers
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    • Posted by Arsiya Hussaini 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Yogita Ingle 6 years, 2 months ago

    Production on an industrial scale, requires growing microbes in very large vessels called fermenters

    Beverages, antibiotics, enzymes are some of the industrial products produced by microbes.

    Fermented beverages

    • Microbes are used for the production of beverages like wine, beer, whiskey, brandy or rum.
    • Saccharomyces cerevisiae, is used for the production of fermented beverages.
    • Malted cereals and fruit juices are fermented by S.cerevisiae to produce ethanol.
    • Wine and beer are produced without distillation.
    • Whisky, brandy and rum are produced by distillation of the fermented broth.

    Antibiotics

    • Antibiotics are the chemical substances which are produced by some microbes and can kill or stop the growth the growth of other microbes.
    • Alexander Flemming discovered penicillin obtained from Penicillium notatum which was the first antibiotic to be discovered.
    • Alexander Fleming while working on Staphylococci bacteria observed a mould growing in one of his unwashed culture plates around which Staphylococci could not grow and he found out that it was due to a chemical produced by Penicillium notatum.
    • Antibiotics are used against the deadly diseases like plague, whooping cough, leprosy, malaria etc.

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    • Posted by Heirangkhongjam Haridas Singh 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 0 answers
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    • Posted by Bishman Malhi 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 2 answers

    Pragati Chaudhary 6 years, 2 months ago

    .the milk come out of the mammary glands during the initial days of lactation is colostrum

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    Yogita Ingle 6 years, 2 months ago

    • Thee milk produced during the first few days of lactation is called colostrum.
    • Colostrum contains antibodies necessary to develop resistance against diseases of the new born baby.

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    • Posted by Kaifi Zia 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Yogita Ingle 6 years, 2 months ago

    Cry proteins are crytalline proteins that are toxic and insecticidal in nature.

    They are produced by bacteria called Bacillus thuringiensis. The toxic protein is present in active form in bacteria which when ingested by an insect leads to the activation of protein and subsequent death of insect.

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    • Posted by Alisha Jajodia 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 0 answers
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    • Posted by Arush Mishra 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Yogita Ingle 6 years, 2 months ago

    Advantages:-
    Inbreeding is necessary if we want to evolve a pure line in any animal.
    • It helps in accumulation of superior genes and elimination of less desirable genes
    • Inbreeding exposes harmful recessive genes that are to be eliminated by selection.
    • Where there is selection at each step, it increases the productivity of inbred population.
    Disadvantages:-
    • reduces fertility
    • decreases productivity.

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    • Posted by Rohen Sinam 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Alisha Jajodia 6 years, 2 months ago

    Provide suitable temp for sperms

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    • Posted by Sanjata Yengkhom Yengkhom 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 2 answers

    Chetna Bhatt 6 years, 2 months ago

    Formation of ova

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    Shalini Maurya 6 years, 2 months ago

    Process of formation of ovum(egg)

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    • Posted by Julekha Bano 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Muskaan Vig 6 years, 2 months ago

    Gene is 'segment of dna' which expresses itself for a particular trait. Dna contains our genetic information via genes. When dna (2m) get arranged in small nucleus with histone proteins etc it forms chromosomes. Gene..dna..chromatin fibre..chromatid..chromosome.

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    • Posted by Rahul Dagar 6 years, 2 months ago

    CBSE > Class 12 > Biology
    • 1 answers

    Meghna Thapar 5 years, 8 months ago

    The main exocrine product of the stomach is gastric juice — a mixture of mucus, hydrochloric acid, and digestive enzymes. Gastric juice is mixed with food in the stomach to promote digestion. ... Parietal cells found in the gastric pits of the stomach produce 2 important secretions: intrinsic factor and hydrochloric acid. Liver is the largest gland in the human body. It carries out many functions such as secretion of bile juices for decomposition of lipids and vitamins, preparation of proteins for blood plasma that enables blood clotting and also detoxification.

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