Lesson Archives

  1. Page No 253: Question 1: Define growth, differentiation, development, dedifferentiation, redifferentiation, determinate growth, meristem and growth rate. Answer: (a) Growth It is an irreversible and permanent process, accomplished by an increase in the size of an organ or organ parts or even of an individual cell. (b) Differentiation It is a process in which the […]
  2. Page No 238: Question 1: Differentiate between (a) Respiration and Combustion (b) Glycolysis and Krebs’ cycle (c) Aerobic respiration and Fermentation Answer: (a) Respiration and combustion Respiration Combustion 1. It is a biochemical process. 1. It is a physiochemical process. 2. It occurs in the living cells. 2. It does not occur in the living cells. […]
  3. Page No 224: Question 1: By looking at a plant externally can you tell whether a plant is C3 or C4? Why and how? Answer: One cannot distinguish whether a plant is C3 or C4 by observing its leaves and other morphological features externally. Unlike C3 plants, the leaves of C4 plants have a special anatomy called Kranz anatomy and […]
  4. Page No 205: Question 1: ‘All elements that are present in a plant need not be essential to its survival’. Comment. Answer: Plants tend to absorb different kinds of nutrients from soil. However, a nutrient is inessential for a plant if it is not involved in the plant’s physiology and metabolism. For example, plants growing […]
  5. Page No 193: Question 1: What are the factors affecting the rate of diffusion? Answer: Diffusion is the passive movement of substances from a region of higher concentration to a region of lower concentration. Diffusion of substances plays an important role in cellular transport in plants. Rate of diffusion is affected by concentration gradient, membrane […]
  6. 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 […]
  7. 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. […]
  8. 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 […]
  9. 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 […]
  10. 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 […]