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Biology World

CHAPTER 10 - (Part -1) - Cell Cycle and Cell Division

  Cell Cycle and Cell Division Cell Cycle: The sequence of events by which a cell duplicates its genome, synthesises the other constituents of the cell and eventually divides into two daughter cells is termed as cell cycle. The cell cycle is divided into two basic phases: 1. Interphase (Resting phase) 2. M Phase (Mitosis phase) Interphase (Resting phase): * The interphase is the time during which the cell is preparing for division by undergoing both cell growth and DNA replication in an orderly manner. * The interphase is divided into three further phases: G1 phase (Gap 1) S phase (Synthesis) G2 phase (Gap 2) G1 phase corresponds to the interval between mitosis and initiation of DNA replication. During G1phase, the cell is metabolically active and continuously grows but does not replicate its DNA. G1 phase is the period when the cell grows and carries out normal metabolism. Most of the organelle duplication also occurs during this phase.   S or syn...
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CHAPTER 9 - (Part -3) - Enzymes

  Enzymes  * Enzymes are proteins which catalyze biochemical reactions in the cells. * There are some nucleic acids that behave like enzymes. These are called ribozymes. * Rate of Reaction: The rate of a physical or chemical process refers to the amount of product formed per unit time. It can be expressed as:    Rate = ∆P / ∆t    Rate can also be called velocity if the direction is specified. Nature of Enzyme Action: Each enzyme (E) has a substrate (S) binding site in its molecule so that a highly reactive enzyme-substrate complex (ES) is produced. This complex is short-lived and dissociates into its product(s) P and the unchanged enzyme with an intermediate formation of the enzyme-product complex (EP). The formation of the ES complex is essential for catalysis. E + S → ES → EP → E + P The catalytic cycle of an enzyme action can be described in the following steps: 1. First, the substrate binds to the active site of the enzyme, fitting into the active site....
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CHAPTER 9 - (Part -2) - Biomacromolecules

  Biomacromolecules Biomacromolecules are polymers that are found in the acid-insoluble fraction of a cell, having a molecular weight greater than 10 kilodaltons. All biomacromolecules are polymers, with the exception of lipids. Examples include proteins, polysaccharides, and nucleic acids. Proteins Proteins are polypeptides, which are polymer and linear chains of amino acids linked by peptide bonds. Characteristics of Proteins:  * Each protein is a polymer of amino acids.  * There are 20 types of amino acids, e.g., alanine and cysteine.  * A protein is a heteropolymer of different amino acids.  * Amino acids may be essential or non-essential.  * Collagen is the most abundant protein in the animal world.  * Ribulose bisphosphate Carboxylase Oxygenase (RuBisCO) is the most abundant protein in the whole of the biosphere. Structure of Protein: A protein can have the following structures: 1. Primary (1⁰) Structure: In this structure, amino acids are arrang...
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CHAPTER 9 - (Part -1) - Biomolecules

Analysis of chemical composition of living organisms, detailing both organic and inorganic components Analysis of Organic Compounds:  * Grinding and Filtration : A living tissue is ground with trichloroacetic acid (Cl 3 CCOOH) to form a slurry. This slurry is then strained through a cheesecloth.  * Fractionation : This process separates the compounds into two fractions:    * Acid-soluble pool (filtrate): Contains thousands of small organic compounds.    * Acid-insoluble fraction (retentate): Contains larger, more complex molecules. Further analysis involves isolating and purifying individual compounds from the acid-soluble pool. This is followed by using analytical techniques to determine their molecular formula and structure. These carbon compounds are collectively called "biomolecules." Classification of biomolecules from a biological perspective:  * Amino Acids: Organic compounds with an amino group (-NH 2 ) and an acidic group (-COOH) attached to...
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Questions Paper - Unit 1

NCERT Biology   Unit I: Diversity in the Living World Chapters 1 to 4 1-Mark Questions (Attempt all 10 questions) (Total: 10 Marks)  * What is the technical name for the statement "as we go higher from species to kingdom , the number of common characteristics goes on decreasing"?  * Give an example of a sterile living organism .  * Name the two components of binomial nomenclature .  * In which group of organisms do we find naked seeds ?  * What is the main criterion for classification used by R.H. Whittaker ?  * Give one example of an organism that is both autotrophic and heterotrophic .  * What is the term used for a collection of preserved plant specimens mounted on sheets?  * Which phylum includes animals with a notochord ?  * Give an example of a plant belonging to the kingdom Plantae that lacks a true root, stem, and leaf.  * Name the first division to have vascular tissues among the Plant Kingdom . 2-Mark Questions (Attempt...
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Question Paper - Chapter 5

 Question Paper 2 "Morphology of Flowering Plants"  1-Mark Questions (Attempt all 10 questions) (Total: 10 Marks)  * What is the main function of the root cap ?  * Give one example of a plant with adventitious roots .  * Which type of venation is found in the leaves of a dicot plant ?  * What is the term for the arrangement of flowers on the floral axis ?  * What is the technical term for the single cotyledon of a maize grain ?  * Name the type of aestivation where margins of petals overlap the margins of the adjacent petal but not in a particular direction.  * Give one example of a plant with parallel venation .  * Which part of the pistil receives pollen grains ?  * What is the term for a fruit that develops from a single flower with a single ovary?  * What is a hypogynous flower ? 2-Mark Questions (Attempt all 5 questions) (Total: 10 Marks)  * Differentiate between fibrous root system and taproot system with an exa...
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Questions Paper - Chapter 6

Questions Paper 1 1-Mark Questions (Attempt all 10 questions) (Total: 10 Marks)  * What is the outermost protective layer of a plant organ called?  * Which type of vascular bundle is characterized by the presence of cambium?  * Name the tissue that forms the continuous undifferentiated mass in a monocot stem.  * In a dicot root, what is the arrangement of xylem called where the protoxylem is located towards the outside?  * What is the main function of the cuticle on the epidermis of a leaf?  * In which part of the dicot stem do lateral roots originate?  * What is the primary function of the cortex in both roots and stems?  * Which type of venation is characteristic of an isobilateral leaf?  * Name the special cells in the epidermis of monocot leaves that help in rolling and unrolling.  * What is the location of the vascular bundles in a monocot stem? 2-Mark Questions (Attempt 3 questions) (Total: 10 Marks)  * Differentiate between t...
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