UNIT 4 - NCERT

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UNIT 4The description of structure and variation of living organisms over aperiod of time, ended up as two, apparently irreconcilable perspectiveson biology. The two perspectives essentially rested on two levels oforganisation of life forms and phenomena. One described at organismicand above level of organisation while the second described at cellularand molecular level of organisation. The first resulted in ecology andrelated disciplines. The second resulted in physiology and of physiological processes , in flowering plants as anexample, is what is given in the chapters in this unit. The processes ofmineral nutrition of plants, photosynthesis, transport , respiration andultimately plant growth and development are described in molecularterms but in the context of cellular activities and even at organismlevel. Wherever appropriate, the relation of the physiological processesto environment is also PHYSIOLOGYChapter 11Transport in PlantsChapter 12Mineral NutritionChapter 13Photosynthesis in HigherPlantsChapter 14Respiration in PlantsChapter 15Plant Growth andDevelopment2022-23MELVIN CALVIN born in Minnesota in April, 1911, received in Chemistry from the University of Minnesota.

11.1.4 Comparison of Different Transport Processes Table 11.1 gives a comparison of the different transport mechanisms. Proteins in the membrane are responsible for facilitated diffusion and active transport and hence show common characterstics of being highly selective; they are liable to saturate, respond to inhibitors and are under

  Transport, Processes, Active, Diffusion, Transport processes, Diffusion and active transport