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3 pm Jan 24, 2013

CBSE Board biology examination

As part of the IBNLive-Topper chat series, Meghna Thapar, biology teacher, will interact with students who will appear for the 2013 CBSE Board examinations which start from March 1. Parents and teachers can also benefit from her tips.
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39 questions answered | 7 questions pending
  • How sexual reproduction is better than asexual reproduction. Asked by: Riya
  • Meghna Thapar sexual reproduction promotes diversity of characters and leads to variations.
  • is it necessary to follow word limit in paper always and not write an extra words Asked by: ansh
  • Meghna Thapar yes, u should attempt according to the marks limit.
  • which part of food for example carbohydrates , etc get absorbed in duodenum ? Is there no breakdown of food molecules in duodenum jejenum? Asked by: Akash
  • Meghna Thapar All solid food materials like proteins, carbohydrates......
  • What will happen if there is no meiosis in an organism? Will that organism survive? Asked by: Akash
  • Meghna Thapar Without meiosis, the chromosome number will not reduce to half in gametes and during fertilization the chromosome number will be pretty large and abnormal organisms will be produced.
  • Please define air layering. Asked by: Akash
  • Meghna Thapar Air layering is the process of removing a large branch or section of the trunk of a tree to create another tree.
  • there is any method to stop menstruation Asked by: pooja
  • Meghna Thapar In normal conditions, menstruation does not take place in case of pregnancy.
  • Is there any difference between alveolus and alveolar duct ? Asked by: Akash
  • Meghna Thapar Alveolus are sockets in the jaws in which the roots of teeth are held in the alveolar process of maxilla with the periodontal ligament whereas Alveolar ducts are tiny ducts that connect the respiratory bronchioles to alveolar sacs, each of which contain a bunch of alveoli (the balls)
  • Mam,Can u give some examples of Value based questions of 10th bio? Asked by: samson
  • Meghna Thapar Example: 1. Mrs. Kumar is pregnant for the last three months and she goes for regular check-up to her doctor. During her last visit, the doctor asked Mrs. Kumar to get an ultrasound done. Both Mr. and Mrs. Kumar went to a radiologist and got the ultrasound done. Once the ultrasound is over, Mr. Kumar asked the doctor whether the baby in the womb is a boy or a girl. (a) What should the doctor reply to the couple? (b) Is it ethical to determine the sex of a child? What should government do to discourage sex determination?
  • which period is called "the of dinosaurs"? Asked by: samson
  • Meghna Thapar Mesozoic Era
  • What is coliform bacteria? Asked by: Akash
  • Meghna Thapar These are Gram negative rod shaped bacteria used in quality analysis of water and food.
  • what is coagulation? Asked by: Ratna
  • Meghna Thapar It is a process in which blood forms a clot.
  • What is the function of the pineal gland? Asked by: Jash Dholani
  • Meghna Thapar This contributes the the alertness or conciousness of one's self and produces "melatonin" which regulates the sleep.
  • What happens to the food in duodenum, jejenum and ileum? Asked by: Akash
  • Meghna Thapar The food gets absorbed in these parts of small intestine.
  • In asexual reproduction or in sexual reproduction in which case offsprings are more identical to their parents. Give reason why or why not. Asked by: Ishant
  • Meghna Thapar Offsprings are identical in asexual reproduction because the offspring is produced by a single organism.
  • like ova release every month sperm also release every month or every day Asked by: pooja
  • Meghna Thapar Sperms get released within few hours in the body of males.
  • What is the function of colon? Asked by: Akash
  • Meghna Thapar The main function of the colon is to extract water and salt from solid wastes before they are eliminated out in the form of faeces.
  • What is amniotic fluid?Is it have any fnction in our body ? Asked by: Akash
  • Meghna Thapar During pregnancy, the growing baby is cushioned inside a fluid-filled bag within your uterus (womb). This bag is called the amniotic sac and the fluid is called amniotic fluid. The amniotic fluid helps: i. protect thebaby from being hurt. ii. protect the baby against infection. iii. maintain a constant temperature in your womb.
  • what r acquired characters? Asked by: samson
  • Meghna Thapar A trait of an organism which is not inherited but develops in response to the environment is called an acquired trait.
  • what is gradual specification? Asked by: samson
  • Meghna Thapar Is it gradual speciation? The gradual model of speciation holds that species originate by slight morphological changes over long time spans is called gradual speciation.
  • what is function of vulva Asked by: gagan
  • Meghna Thapar The vulva has three main functions: 1. It protects women's sexual organs and the urinary opening from trauma and infection. 2. It is vital for women's sexual response. The clitoris is the main organ of sexual arousal and orgasm in most women. 3. The vulva and the perineum stretch to accommodate childbirth.
  • What is the draw backs of darwin,s theory? Asked by: samson
  • Meghna Thapar It could not explain how variations arise.
  • explain carbon cycle? Asked by: pragya
  • Meghna Thapar The Carbon Cycle is a complex series of processes through which all of the carbon atoms in existence rotate.
  • Why after several weeks the part above the ringed bark is swollen and lower part is shrivelled in a woody plant ? Asked by: Akash
  • Meghna Thapar The stem just above the ring shows a swelling due to accumulation of organic substances synthesised by the leaves. The adventitious roots may develop above the ring so sometimes, the lower part is shrivelled in a woody plant.
  • in vasectomy some part of sperm duct is cut and tied up then with release of more and more sperm they get collected in duct and it can blast or not Asked by: pooja
  • Can u please tell me how punet square is drawn Asked by: Anirudh
  • Meghna Thapar Punet square is a checker-board used to show the result of cross between two organisms. In it, the gametes from one hybrid should be written on the top of the square and the gametes from other hybrid should be written on left side and then multiplied.
  • what is book is important for class 10 th cbse students except ncert. Asked by: Ishant
  • Meghna Thapar See, there are lot many good books for science. It depends on your interest, you want to practice; like in Bio lakmir singh is good one.....
  • what is geological isolation Asked by: Anirudh
  • Meghna Thapar It is the major factor in speciation of sexually reproducing animals because it interrupts the flow of genes between their isolated populations through the gametes.
  • What is triglyagerides? Asked by: Akash
  • Meghna Thapar Triglycerides are the lipids which are derived from glycerol and fatty acids.
  • What is the compositon of sperm means what is its head and tail contain? Asked by: Akash
  • Meghna Thapar Head of the sperm contains a hydrolytic enzyme which helps the sperms to penetrate into ovum. Tail contains a small amount of the cytoplasm which provides mobility to the sperm.
  • Define homologous and analogous organs. Asked by: Ishant
  • Meghna Thapar Homologous organs: Those organs which have the same basic structure but different functions. Analogous organs: Those organs which have different basic structure but have similar appearance and perform similar functions.
  • pls explain tissues Asked by: vans
  • Meghna Thapar A group of biological cells that perform similar functions are called tissues.
  • what is hybrid cross? Asked by: samson
  • Meghna Thapar Hybrids between different species within the same genus are sometimes known as interspecific hybrids or crosses.
  • Meghna Thapar The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out through both biological and physical processes. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification.
  • define genetic drift. Asked by: Ishant
  • Meghna Thapar The drastic changes in the frequencies of particular genes by chances alone in the process of speciation is called genetic drift.
  • define evolution Asked by: Ishant
  • Meghna Thapar Evolution is the sequence of changes which takes place in the primitive organisms over millions of years in which new species are produced.
  • What is monosaccharides? Asked by: Akash
  • Meghna Thapar Monosaccharides are the simplest carbohydrate units.
  • Can u pleas explain the origin of life? Asked by: samson
  • Meghna Thapar Theories on the Origin of Life: (i) Special Creation: According to this theory, the life on earth has been created by supernatural power, the God. The life is immutable and has not changed ever since its origin. (ii) Spontaneous Generation: The theory states that life originated from the non-living things in a spontaneous manner. It was believed that insects have arisen from dew under the influence of heat and moisture. Similarly, fishes, frogs, snakes and mice were produced from the mud of the Nile under the warmth of the sun. The idea of spontaneous generation was appreciated by Aristotle. However, Louis Pasteur did not accept this theory and demonstrated that life originated from the pre-existing life. (iii) Extraterrestrial or Cosmic origin: This theory states that life is coeternal with matter without any beginning. The organisms have accidently reached the earth from an extraterrestrial source in the form of resistant spores or seeds. (iv) Terrestrial or Abiogenic origin: This theory states that the first form of life arose slowly through evolutionary forces from non-living molecules through series of sequential chemical reactions. The theory of Abiogenic origin has scientific basis. It is also supported by Urey and Miller who favoured Oparin-Haldane hypothesis. According to this, the first living being arose from non-living.
  • Can you please explain different RNA's? Asked by: Mohit
  • Meghna Thapar There are three types of RNA: (i) r-RNA - It forms about 80% of total cellular RNA and is a component of ribosomes. It is a single stranded molecule but twisted on itself. It serves to release m-RNA from DNA. (ii) m-RNA - It is formed by DNA template in the nucleus and moves to the cytoplasm. It carries codon which serves as a message tape to be decoded into a protein. (iii) t-RNA - It is smallest of all the RNAs. It picks up activated amino acid from the cytoplasm and supplies it to m-RNA in cytoplasm.
  • Please explain biological magnification. Asked by: Sara
  • Meghna Thapar The accumulation of harmful chemicals in the body of living organisms at different trophic levels in a food chain is called biological magnification.

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Meghna Thapar
Biology teacher