Lesson Archives

  1. Page No 171: Question 1: What is the average cell cycle span for a mammalian cell? Answer: The average cell cycle span for a mammalian cell is approximately 24 hours. Question 2: Distinguish cytokinesis from karyokinesis. Answer: Cytokinesis  Karyokinesis  (i) Cytokinesis is the biological process involving the division of a cell’s cytoplasm during mitosis or […]
  2. Page No 160: Question 1: What are macromolecules? Give examples. Answer: Macromolecules are large complex molecules that occur in colloidal state in intercellular fluid. They are formed by the polymerization of low molecular weight micromolecules. Polysaccharides, proteins, and nucleic acids are common examples of macromolecules. Question 2: Illustrate a glycosidic, peptide and a phospho-diester bond. […]
  3. Page No 141: Question 1: Which of the following is not correct? (a) Robert Brown discovered the cell. (b) Schleiden and Schwann formulated the cell theory. (c) Virchow explained that cells are formed from pre-existing cells. (d) A unicellular organism carries out its life activities within a single cell. Answer: (a) Robert Brown did not discover […]
  4. Page No 122: Question 2: Answer the following: (i) What is the function of nephridia? (ii) How many types of nephridia are found in earthworm based on their location? Answer: (i) Nephridia are segmentally arranged excretory organs present in earthworms. (ii) On the basis of their location, three types of nephridia are found in earthworms. They are: (a) Septal nephridia: These […]
  5. Page No 99: Question 1: State the location and function of different types of meristem. Answer: Meristems are specialised regions of plant growth. The meristems mark the regions where active cell division and rapid division of cells take place. Meristems are of three types depending on their location. Apical meristem It is present at the […]
  6. Page No 82: Question 1: What is meant by modification of root? What type of modification of root is found in the (a) Banyan tree (b) Turnip (c) Mangrove trees Answer: Primarily, there are two types of root systems found in plants, namely the tap root system and fibrous root system. The main function of the roots is […]
  7. Page No 62: Question 1: What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account? Answer: For the classification of living organisms, common fundamental characteristics are considered. If we consider specific characteristics, then each organism will be placed in a separate group and the […]
  8. Page No 44: Question 1: What is the basis of classification of algae? Answer: Algae are classified into three main classes – Chlorophyceae, Phaeophyceae, and Rhodophyceae. These divisions are based on the following factors: (a) Major photosynthetic pigments present (b) Form of stored food (c) Cell wall composition (d) Number of flagella and position of […]
  9. Page No 28: Question 1: Discuss how classification systems have undergone several changes over a period of time? Answer: The classification systems have undergone several changes with time. The first attempt of classification was made by Aristotle. He classified plants as herbs, shrubs, and trees. Animals, on the other hand, were classified on the basis […]
  10. Page No 15: Question 1: Why are living organisms classified? Answer: A large variety of plants, animals, and microbes are found on earth. All these living organisms differ in size, shape, colour, habitat, and many other characteristics. As there are millions of living organisms on earth, studying each of them is impossible. Therefore, scientists have […]