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There is no signal to indicate the end of one codon and beginning of the next codon i.e. codes are arranged without space. Thus, genetic code is commaless. The same codon shall not code for two or more different aminoacids. Thus, the genetic code is non-ambiguous. The genetic code occurs in all organisms. Thus, the genetic code shows universality. The three triplets UAA, UAG and UGA do not code for any aminoacid. These are called non-sense codon. The other 61 codons are called sense codons. Central dogma of molecular biology Aminoacids are linked by means of peptide bonds to form a protein. A protein may contain thousands of aminoacids. The central dogma of molecular biology is illustrated as below. Fig.3.11 Central dogma of molecular biology 140
The transfer of message present in the DNA is the initial step and the message is transferred to mRNA. This is known as transcription. Based on the message in the codon, the proteins are synthesized. This stage is called translation. Transcription The process by which an enzyme system transfers the genetic information of DNA into RNA strand is called transcription. It is the process of copying of a complementary mRNA strand on a DNA strand. It requires a template DNA, ribonucleotides, triphosphates like ATP and GTP, metal ions Mg 2+ and Mn 2+ and RNA polymerase. The RNA polymerase has a sigma factor, which initiates transcription. During transcription, the DNA strands unwind and one of the strands functions as the template for mRNA. The nucleotides of mRNA so formed are complementary to those of DNA strand. However, in mRNA uracil replaces thymine of DNA. The information for protein synthesis present in DNA is now transcribed to mRNA. This process is known as transcription. Translation According to genetic information present in the mRNA, specific aminoacids are assembled to form polypeptide chain. The process of translating the nucleotide sequence of mRNA into the aminoacid sequence of a polypeptide is called translation i.e. it means decoding the message for protein synthesis. It involves attachment of mRNA to the 30S segment of the ribosomes. The enzymes activate the aminoacids. Specific tRNA picks up the activated aminoacids. Initially, the tRNA bonds with aminoacid molecules. This reaction is catalysed by aminoacyl tRNA synthetase. The tRNAs containing specific aminoacids are now referred to ‘charged tRNAs’. The actual process of translation begins, when the initiating aminoacyl tRNA binds to the ribosome and base pairs with mRNA codon AUG. This reaction is promoted by initiating factor. The polypeptide chain increases in length by the linking of successive aminoacids as per the genetic code. Thereby, elongation of polypeptide chain takes place. This reaction is promoted by elongation factor. 141
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BOTANY Higher Secondary Second Year
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Preface The most important and cruc
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1. Taxonomy PRACTICALS (30 periods)
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1. TAXONOMY OF ANGIOSPERMS Taxonomy
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compared to perianth with two whorl
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a total variety or species. To conc
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well known system of classification
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Self Evaluation I . Choose and writ
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Series (iii) Calyciflorae It includ
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Class III Monocotyledonae Seeds of
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5. How many families were described
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Flower Bracteate or ebracteate, bra
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A twig Sepal Epicalyx Calyx A petal
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Self evaluation I . Choose and writ
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Inflorescence Usually a raceme eg.
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Calyx Ovary Gynoecium Bracteole Flo
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5. Fibre plants Fibres obtained fro
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1.3.3. RUBIACEAE - the coffee famil
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Stem Leaf Aerial, erect, branched,
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1. Beverage plants ECONOMIC IMPORTA
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1.3.4. ASTERACEAE - the sunflower f
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Habit Root Stem Leaf Botanical desc
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Fruit Seed A cypsela. Non-endosperm
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Flower Bracteate (eg. Petunia hybri
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Stamen Epipetalous stamens T.S. of
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(eg. Jatropha curcas). In xerophyti
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Perianth Tepals 5, arranged in sing
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1. Food plants ECONOMIC IMPORTANCE
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MONOCOT FAMILY 1.3.7 MUSACEAE - the
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Habit Root Stem Botanical descripti
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Androecium Stamens 6, in two whorls
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1.3.8. ARECACEAE - the palm family
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Habit Botanical description of Coco
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Gynoecium Absent but pistillode is
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II. Answer the following questions
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Classification of meristem Based on
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oval, spherical, rectangular, cylin
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Fibres Fibre cells are dead cells.
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Tracheid conducting elements in ang
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a lining layer of cytoplasm. This i
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2. Epidermis protects the underlyin
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made up of barrel shaped parenchyma
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2.2. Anatomy of monocot and dicot r
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The endodermal cells, which are opp
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Cortex Cortex consists of only pare
Page 95 and 96: II. Answer the following questions
Page 97 and 98: Ground plan A sector enlarged Fig.
Page 99 and 100: Ground plan A sector enlarged Fig.
Page 101 and 102: Xylem Xylem consists of xylem fibre
Page 103 and 104: 2.4. Anatomy of a dicot and monocot
Page 105 and 106: Vascular tissues Vascular tissues a
Page 109 and 110: 1. Formation of interfascicular cam
Page 111 and 112: Formation of periderm As secondary
Page 113 and 114: Each annual ring refers to one year
Page 115 and 116: 8. What are complementary cells? 9.
Page 117 and 118: chromosome has one centromere and t
Page 119 and 120: Chromosomal puff Dark band inter ba
Page 121 and 122: The genome size of an individual is
Page 123 and 124: ound pollen (bbll). All the F1 hybr
Page 125 and 126: points called chiasmata. Crossing o
Page 127 and 128: 3.4. Recombination of chromosome Th
Page 129 and 130: Point or gene mutation Point mutati
Page 133 and 134: 127 Fig. 3.6 Chromosomal aberration
Page 135 and 136: Autopolyploidy Ploidy - flow chart
Page 137 and 138: Self evaluation I . Choose and writ
Page 139 and 140: cells was injected into the mouse,
Page 141 and 142: Replication fork Super coil DNA pol
Page 143 and 144: 3.8. Structure of RNA and its types
Page 145: Role of RNA in protein synthesis Th
Page 149 and 150: IV. Answer the following questions
Page 151 and 152: to join DNA fragments. Thus the res
Page 153 and 154: Ti plasmid T-DNA Foreign DNA Bacter
Page 155 and 156: Restriction enzyme and ligase do no
Page 157 and 158: 4.2 Transgenic plants Introduction
Page 159 and 160: introducing Bt toxin gene in cotton
Page 161 and 162: 2. The number of transgenic plants
Page 163 and 164: Pot plant Explant Inoculation Surfa
Page 165 and 166: . Embryogenesis Formation of embryo
Page 169 and 170: Strain A Strain B Isolation of prot
Page 171 and 172: The term ‘single cell protein’
Page 173 and 174: 8. What is PEG? 9. How do you remov
Page 175 and 176: Many enzymes consists of a protein
Page 177 and 178: 5.1.3. Theories explaining the mech
Page 181 and 182: 5.2.1. Significance of photosynthes
Page 183 and 184: The reactions of photosynthesis can
Page 185 and 186: 179 Fig. 5.8. Non-cyclic photophosp
Page 187 and 188: Difference between cyclic and noncy
Page 189 and 190: power NADPH 2 . So, two molecules o
Page 191 and 192: Fig.5.11 Hatch-Slack pathway of CO
Page 193 and 194: Difference between C 3 and C 4 phot
Page 195 and 196: Glycine molecules enter into mitoch
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Among leaf factors, such as leaf ag
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Epiphyte eg. Vanda Aerial root Part
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When an insect is attracted by the
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11. The gas evolved during photosyn
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40. Explain the test tube and funne
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201 Fig. 5.17 Overall scheme of res
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Fig. 5.18 Process of Glycolysis 203
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decarboxylation and dehydrogenation
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9. The malic acid is oxidized to ox
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is fixed in the vertical position w
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Nonoxidative phase In this phase, v
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Respiratory quotient for anaerobic
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5. Fructose 1,6-bisphosphate is cle
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32. Write short notes on anaerobic
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this phase is called lag phase. It
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Physiological effects of auxin Auxi
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endosperm of coconut. Cytokinin occ
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4. Bakanae disease in paddy is caus
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5.5. Photoperiodism and vernalizati
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c. sunflower d. maize 4. Which of t
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1. To develop more food crops 2. To
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Clonal selection Crops like sugarca
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The haploid individual plant will h
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methods new improved crops are obta
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6.2. Crop diseases and their contro
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Pathogen The mycelium of Cercospora
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3. They also bring about considerab
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It is hoped that one day geneticall
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2. The genetic resources of the dev
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This will affect millions of uneduc
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additives. It depends upon crop rot
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COMMONLY AVAILABLE MEDICINAL PLANTS
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urinary infections, tuberculosis, m
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Groundnut oil is used to a limited
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