Grade 12

Multicellularity: Structure and Function - Plant Life

Forms and function

(i) Tissues: types of plant tissues: Meristematic: Classification of Meristematic tissue, tunicacorpus theory, histogen theory, root apex. Permanent: Structure and function of simple tissues ( parenchyma, collenchyma and sclerenchyma) and complex tissues (xylem and phloem) , types of vascular bundles, T. S of young dicot and monocot stem, T.S of young dicot and monocot root and V.S. of dicot and monocot leaf. Secondary growth: brief idea of formation of secondary xylem and secondary phloem by cambium ring formation, annual rings, heartwood and sapwood .

(ii) Absorption and movement of water in plants: diffusion, osmosis, osmotic pressure, turgor pressure, wall pressure, water potential, pressure potential, diffusion pressure deficit. Types of soil water, mechanism of water absorption (active and passive absorption) , root pressure, guttation, transpiration pull theory for ascent of sap, transpiration, mechanism of opening and closing of stomata (active potassium theory) .

(iii) Mineral nutrition: macronutrients and micronutrients (role and deficiency

symptoms) , criteria for essentiality of elements, aeroponics and hydroponics,

passive absorption ( ion exchange mechanism) and active absorption of mineral nutrients,

nitrogen nutrition in plants.

(iv) Modes of nutrition: parasitic, saprophytic, symbiotic and insectivorous (brief idea with examples) , transport of solutes, photosynthesis: ultra structure of chloroplast, photochemical and biosynthetic phases, absorption and action spectra, factors influencing photosynthesis,

photophosphorylation; photorespiration.

(v) Reproduction and development in angiosperms: vegetative reproduction, sexual reproduction: development of male and female gametophytes, types of ovules, pollination, fertilisation and development of endosperm, embryo, seed and fruits .

(vi) Differentiation and organ formation.