How a plant grows and how fast. The three phases of growth, arithmetic and geometric growth, absolute and relative growth rate, and the conditions growth needs. Then differentiation, dedifferentiation, redifferentiation, development and plasticity.
3 lessons, about 1 h 30 min3 simulations11 problems3 practice questionsPython in every lesson
Created by StemPy LabGrowth is a permanent, irreversible increase in the size of a cell, an organ or the whole plant, and it uses energy. Plant growth is open: meristems keep adding new cells all through life. Growth can be measured as fresh weight, dry weight, length, area, volume or cell number. In a root or a shoot the cells pass through three phases: meristematic, elongation and maturation.
Growth rate is the increase in growth in a unit of time. In arithmetic growth only one daughter cell keeps dividing, so the length rises in a straight line, . In geometric growth both daughter cells divide, giving a lag phase, a log phase and a stationary phase, the sigmoid curve, with . Absolute growth rate is the total gain in a unit of time. Relative growth rate is the gain compared with the starting size. Growth needs water, oxygen, nutrients and a suitable temperature.
Differentiation is the maturation of cells made by the meristems, as they take up the shape and job of a permanent tissue. Living cells that have lost the power to divide can start to divide again (dedifferentiation), and the new cells can mature again (redifferentiation). Development is the sum of growth and differentiation. Plants show plasticity: one plant can make different forms, as in heterophylly. Development is controlled by factors inside the plant and by factors outside it.
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