Growth and Development in Plants : 12th Class Biology Question Answer Lesson 20 – NIOS

Growth and Development in Plants : 12th Class Biology Question Answer Lesson 20 – NIOS

Growth and Development in Plants class 12th biology question answer


  1. Distinguish between growth and development.
    Ans. Growth : Increase in number and size of a cell, organ organism.
    Development : Series of qualitative & quantitative changes including
    growth, differentiation and maturation.
  2. What is differentiation?
    Ans. Process of change in cells, tissues or organs in order to carry out different functions.
  3. What role does it play in plant growth and development?
    Ans. Similar cells organise to form a group called tissue to perform a particular function


  1. Name the plant hormones concerned with the following:
    (i) Elongation of cell – Auxin
    (ii) Shedding of leaves – Ethylene
    (iii) Breaking seed dormancy – Abscissic acid
  2. Mention two functions of Auxin
    Ans. (i) Cell elongation (ii) Delays fall of leaves (iii) suppresses growth of lateralbud (any two)
  3. What is the difference between dedifferentiation and redifferentiation?
    Ans. Dedifferentiation : Process by which precursor cells become distinct celltypes to perform a specific function.
    Redifferentiation : Process by which the plant cells while undergoing
    dedifferentiation lose their capacity to divide once again but mature to
    perform specific functions.
  4. Which two hormones are essential for vascular tissue differentiation?
    Ans. Auxin and Cytokinin.


  1. Distinguish between Phototropism and Geotropism
    Ans. Movement induced by light – Phototropism
    Movement induced by gravity – Geotropism
  2. Give two examples of turgor movement
    Ans. (i) Closure of leaves on fall of darkness
    (ii) dropping of leaves on touch
    (iii) closing leaves of venus fly trap to catch a landing insect (any two)


  1. State the different stages of cellular growth.
  2. Distinguish between growth and development.
  3. What is a sigmoid growth curve? State the different phases of sigmoid curve.
  4. Describe the various external factors that affect the growth of plants.
  5. What is vernalisation?
  6. Define the term Photoperiodism.
  7. What is auxin? What is its role in the growth of plants?
  8. State any two functions of Gibberellin?
  9. Explain the role of Cytokinins and Ethylene in growth and development of Heredityplants.
  10. Distinguish between epigeal germination and hypogeal germination.
  11. What is meant by seed germination? Describe the various factors responsiblefor seed germination.
  12. What is senescence?
  13. State any two practical utilities of growth hormones.
  14. What is biological stress? Describe the different types of biological stress.
  15. What is apical dominance? Name the hormone responsible for it.
  16. What is meant by plant movement? Describe any two types of movement ofplants with example.

NIOS 12th class biology Q Ans

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