{"id":34100,"date":"2022-11-14T16:48:37","date_gmt":"2022-11-14T11:18:37","guid":{"rendered":"https:\/\/tsboardsolutions.com\/?p=34100"},"modified":"2022-11-16T14:32:39","modified_gmt":"2022-11-16T09:02:39","slug":"ts-inter-2nd-year-botany-study-material-chapter-10","status":"publish","type":"post","link":"https:\/\/tsboardsolutions.com\/ts-inter-2nd-year-botany-study-material-chapter-10\/","title":{"rendered":"TS Inter 2nd Year Botany Study Material Chapter 10 Molecular Basis of Inheritance"},"content":{"rendered":"

Telangana TSBIE\u00a0TS Inter 2nd Year Botany Study Material<\/a> 10th Lesson Molecular Basis of Inheritance Textbook Questions and Answers.<\/p>\n

TS Inter 2nd Year Botany Study Material 10th Lesson Molecular Basis of Inheritance<\/h2>\n

Very Short Answer Type Questions<\/span><\/p>\n

Question 1.
\nWhat is the function of histones in DNA packaging?
\nAnswer:<\/p>\n

    \n
  1. Histones are positively charged basic proteins. They are organized to form a unit of eight molecules called histone octamer.<\/li>\n
  2. The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called nucleOsome.<\/li>\n<\/ol>\n

    Question 2.
    \nDistinguish between heterochromatin and euchromatin. Which of the two is transcriptionally active? [Mar. 2020]
    \nAnswer:
    \n1. Euchromation :
    \nRegions of chromatin that are loosely packed and stained lightly. It is transcriptionally active.<\/p>\n

    2. Heterochromation :
    \nRegions of chromatin that are densely packed and stained dark. It is transcriptionally inactive.<\/p>\n

    Question 3.
    \nWho proved that DNA is genetic material? What is the organism they worked on? [May 2017]
    \nAnswer:<\/p>\n

      \n
    1. Alfred Hershey and Martha Chase proved that DNA is genetic material.<\/li>\n
    2. They worked with viruses that infect bacteria, bacteriophages.<\/li>\n<\/ol>\n

      Question 4.
      \nWhat is the function of DNA polymerase?
      \nAnswer:<\/p>\n

        \n
      1. DNA polymerase uses a DNA template to catalyze polymerization of deoxynucleotides.<\/li>\n
      2. It is highly efficient and catalyses polymerization in only one direction (5′ \u2192 3′) with high degree of accuracy.<\/li>\n<\/ol>\n

        Question 5.
        \nWhat are the components of a nucleotide? [Mar. ’18, ’17; May ’14]
        \nAnswer:<\/p>\n

          \n
        1. A pentose sugar, a phosphate group and a nitrogen base are the 3 components of a nucleotide.<\/li>\n
        2. The pentose sugar is ribose in nucleotides of RNA and it is deoxyribose in nucleotides of DNA.<\/li>\n<\/ol>\n

          \"TS<\/p>\n

          Question 6.
          \nWrite the structure of chromatin.
          \nAnswer:<\/p>\n

            \n
          1. Nucleosomes are formed due to wrapping of negatively charged DNA around the positively charged Histone octamers. These repeating units in the nucleus form chromatin.<\/li>\n
          2. The nucleosomes in chromatin are seen as ‘beads – on – string’.<\/li>\n<\/ol>\n

            Question 7.
            \nWhat is the cause of discontinuous synthesis of DNA on one of its parental strands? What happens to these short stretches of synthesised DNA?
            \nAnswer:<\/p>\n

              \n
            1. The DNA – dependent DNA polymerase can catalyze polymerization in only one direction, 5′ \u2192 3′ and hence DNA synthesis is discontinuous on lagging of strand (with 5′ \u2192 3′ polarity) of parental DNA.<\/li>\n
            2. The discontinuously synthesized Okazaki fragments on lagging strand are later joined by DNA ligase to form a continuous strand.<\/li>\n<\/ol>\n

              Question 8.
              \nGiven below is the sequence of coding strand of DNA in a transcription unit 3′ – AATGCAGCTATTAGG – 5′
              \nWrite the sequence of
              \na) its complementary strand
              \nb) the mRNA
              \nAnswer:
              \na) Its complementary strand
              \n5′ – TTACGTCGATAATCC – 3′<\/p>\n

              b) The mRNA
              \n5′- UUACGUCGAUAAUCC – 3′<\/p>\n

              Question 9.
              \nIn a nucleus, the number of ribonucleoside triphosphates is 10 times the number of deoxy ribonucleoside triphosphates, but only deoxyribonucleotides are addded during the DNA replication. Suggest a mechanism.
              \nAnswer:<\/p>\n

                \n
              1. DNA is a polymer made of deoxyribonucleotides.<\/li>\n
              2. Absence of 2 – OH group is nuclosides confers stability to DNA molecules.<\/li>\n<\/ol>\n

                Question 10.
                \nName any three viruses which have RNA as the genetic material.
                \nAnswer:<\/p>\n

                  \n
                1. Tobacco Mosaic virus<\/li>\n
                2. Polio virus<\/li>\n
                3. HIV<\/li>\n
                4. QB Bacteriophage<\/li>\n<\/ol>\n

                  Question 11.
                  \nWrite the sequence of nucleotides after single base insertion and deletion in the given gene:
                  \nGene: THE CAT ATE THE FAT RAT
                  \nAnswer:
                  \n1. If single base T is inserted between ‘THE’ and ‘CAT’, then
                  \nGene : THE TCA TAT ETH EFA TRA T<\/p>\n

                  2. If single base C is deleted from ‘CAT’, then
                  \nGene: THE ATA TET HEF ATR AT<\/p>\n

                  Question 12.
                  \nWhy was DNA chosen over RNA as genetic material in the majority of the organisms?
                  \nAnswer:<\/p>\n

                    \n
                  1. RNA consists of 2 – OH’ group at every nucleotide which is reactive group and makes RNA liable and eassily degradable. It is single stranded, catalyst, reactive and hence unstable.<\/li>\n
                  2. DNA lacks 2 – OH’ group, double stranded, consists of thymine and resists changes by evolving a process of repair. Hence it is a stable genetic material in majority of the organisms.<\/li>\n<\/ol>\n

                    Question 13.
                    \nWhat are the components of a transcription unit? [March 2019]
                    \nAnswer:
                    \nThe three major components of a transcription unit are (1) A Promoter (2) The structural gene (3) A terminator.<\/p>\n

                    \"TS<\/p>\n

                    Question 14.
                    \nWhat is the difference between exons and introns?
                    \nAnswer:
                    \n1. Exons :
                    \nThe coding (expressed sequences in split genes of eukaryotes and will appear in processed (matured) RNA.<\/p>\n

                    2. Introns :
                    \nThe non coding sequences in split genes of eukaryotes that interrupt introns and they do not appear in processed RNA.<\/p>\n

                    Question 15.
                    \nWhat is meant by capping and tailing? [May 2017]
                    \nAnswer:
                    \n1. Capping :
                    \nIt is a process in which, an unusual nucleotide (methyl guanosine triphosphate) is added to the 5′ end of hn RNA.<\/p>\n

                    2. Tailing :
                    \nIn this process, adenylate residues (200 – 300) are added at 3′ – end in a template independent manner.<\/p>\n

                    Question 16.
                    \nWhat is meant by point mutation? Give an example. [May 2014]
                    \nAnswer:<\/p>\n

                      \n
                    1. The mutation that occurs in a single base pair of a gene is called point (gene) mutation.<\/li>\n
                    2. A point mutation in the gene for Beta globin chain (in human haemoglobin) results a disease, sickle cell anaemia.<\/li>\n<\/ol>\n

                      Question 17.
                      \nDefine peptide bond. Why are proteins referred to as polypeptide chains?
                      \nAnswer:<\/p>\n

                        \n
                      1. The bond between two adjacent amino acids in a protein is known as peptide bond.<\/li>\n
                      2. Proteins are the macromolecules and polymers. Amino acids, are joined by many peptide bonds to form proteins and hence are referred as polypeptide chains.<\/li>\n<\/ol>\n

                        Question 18.
                        \nWhat is meant by charging of tRNA?
                        \nAnswer:<\/p>\n

                          \n
                        1. Charging of tRNA (amino acylation of tRNA): Amino acids are activated in the presence of ATP and linked to their cognate tRNAs.<\/li>\n
                        2. This favours the formation of peptide bond by providing energy.<\/li>\n<\/ol>\n

                          Question 19.
                          \nWhat is a regulator and a promoter?
                          \nAnswer:<\/p>\n

                            \n
                          1. Regulator : This gene directs the activity of the operator gene by producing an inhibitor protein called repressor.<\/li>\n
                          2. Promoter is a region of DNA where RNA polymerase binds and initiates transcription.<\/li>\n<\/ol>\n

                            \"TS<\/p>\n

                            Question 20.
                            \nDuring DNA replication, why is it that the entire molecule does not open in one go? Explain replication fork.
                            \nAnswer:<\/p>\n

                              \n
                            1. For long DNA molecules, the entire molecule does not open in one go due to very high energy requirement.<\/li>\n
                            2. The replication occur within a small opening of the DNA helix referred to as replication fork. This is the Y-shaped structure formed when the double-stranded DNA is unwounded upto a point during its replication.<\/li>\n<\/ol>\n

                              Question 21.
                              \nWhat is the function of the codon-AUG? [Mar. ’20, ’14]
                              \nAnswer:<\/p>\n

                                \n
                              1. AUG acts as the initiation codon (start codon) during formation of mRNA.<\/li>\n
                              2. It also codes for an aminoacid, Methionine.<\/li>\n<\/ol>\n

                                Question 22.
                                \nDefine stop codon. Write the codons. [March 2019]
                                \nAnswer:<\/p>\n

                                  \n
                                1. The codons that do not code for any amino acid and responsible for termination of protein synthesis \/ translation process are called as stop codons.<\/li>\n
                                2. There are 3 stop codons ie., UAA, UAG and UGA.<\/li>\n<\/ol>\n

                                  Question 23.
                                  \nWhat is the difference between the template strand and a coding strand in a DNA molecule? [May 2014]
                                  \nAnswer:<\/p>\n\n\n\n\n\n
                                  Template strand<\/td>\nCoding strand<\/td>\n<\/tr>\n
                                  1) The strand with 3′ \u2192 5′ polarity is a replicating DNA.<\/td>\n1) It is a strand with 5′ \u2192 3′ polarity in a replicating DNA.<\/td>\n<\/tr>\n
                                  2) This consists of structural gene flanked by promoter and terminator sequences respected at 3′ and 5′ ends.<\/td>\n2) It has terminator towards 3′ end.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                                  \"TS<\/p>\n

                                  Question 24
                                  \nWrite any two chemical differences between DNA and RNA. [March 2017]
                                  \nAnswer:<\/p>\n\n\n\n\n\n
                                  DNA<\/td>\nRNA<\/td>\n<\/tr>\n
                                  1) DNA has deoxyribose sugar.<\/td>\n1) RNA has Ribose sugar.<\/td>\n<\/tr>\n
                                  2) It has thymine and cytosine as pyrimidine bases.<\/td>\n2) It has uracil and cytosine as pyramidine base.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

                                  Question 25.
                                  \nIn a typical DNA molecule, the proportion of Thymine is 30% of the N bases. Find out the percentages of other N bases.
                                  \nAnswer:<\/p>\n

                                    \n
                                  1. According to Erwin Chargaff in double stranded DNA the ratio between A and T and between G and C are constant and each equals one.<\/li>\n
                                  2. Adenine – 30%, Guanine – 20%, Cytocine – 20%.<\/li>\n<\/ol>\n

                                    Question 26.
                                    \nThe proportion of nucleotides in a given nucleic acid are: Adenine 18%, Guanine 30%, Cytosine 42%, and Uracil 10%. Name the nucleic acid and mention the number of strands in it. [March 2018]
                                    \nAnswer:<\/p>\n

                                      \n
                                    1. As there is Uracil (pyramidine) is the given problem the nucleic acid is RNA.<\/li>\n
                                    2. The proportion of A \u2260 U and G \u2260 C, so it is single stranded RNA.<\/li>\n<\/ol>\n

                                      Question 27.
                                      \nIf the base sequence of a codon in mRNA is 5′ AUG-3′. What is the sequence of tRNA pairing with it?
                                      \nAnswer:
                                      \n3′ – UAC – 5′<\/p>\n

                                      Short Answer Type Questions<\/span><\/p>\n

                                      Question 1.
                                      \nDefine transformation in Griffith’s experiment. Discuss how it helps in the identification of DNA as genetic material.
                                      \nAnswer:
                                      \nTransformation is defined as the uptake of a naked DNA molecule of the fragments of a bacterial cell and the incorporation of this DNA molecule into the recepient chromosome in a heritable form.<\/p>\n

                                      In 1928 Frederick Griffith performed the experiments on Bacterial transformation with Streptococcus pneumonia the bacterium causing pneumonia. During the course of his experiment he found that a living organism (bacteria) could change in physical form.<\/p>\n