9.3  Growth in Plants

big ninja

Essential Idea:

Plants adapt their growth 

to environmental conditions


  • Undifferentiated cells in the meristems of plants allow indeterminate growth
  • Mitosis and cell division in the shoot apex provide cells needed for extension of the stem and development of leaves
  • Plant hormones control growth in the shoot apex
  • Plant shoots respond to the environment by tropisms
  • Auxin efflux pumps can set up concentration gradients of auxin in plant tissue
  • Auxin influences cell growth rates by changing the pattern of gene expression


  • Micropropagation of plants using tissues from the shoot apex, nutrient agar gels and growth hormones
  • Use of micropropagation for rapid bulking up of new varieties, production of virus-free strains of existing varieties and propagation of orchids and other rare species