13.5 Plant Growth and Development Pages 605-612
Walking palm • The adventitious roots in the shade die and new roots in the direction of the sun form.
Growth • Increase in size
Differentiation • A cell becomes specialized to perform a particular function.
Apical meristem • found at the tips of plant’s buds, stems and roots. • primary growth occurs here • plant height increases
Lateral meristem • found at the sides of plant’s buds, stems and roots. • causes secondary growth • increases the width of the plant
Primary Growth • Apical meristem cells divide and elongate • Differentiation into epidermal, parenchyma or vascular cell types.
Shoot apical meristem becomes stems, leaves and reproductive organs • Root apical meristem has three zones: • Zone of maturation • Zone of elongation • Zone of cell division
Secondary growth • Only in woody species after first year. • Example: vascular cambium and cork cambium
Light • Photoreceptor- a molecule that reacts when struck by light of a certain intensity and/or wavelength. • Some seeds need light to germinate Example: lettuce • Some seeds need darkness to germinate Example: lilly
Photoperiod • Plants respond to daylength • Timing of flowers Example: Spinach- long daylength Example: Tulip-short daylength
Macronutrients • Large quantities (more than 1g/kg of dry mass) Examples: N, P, K
Carbon • From carbon dioxide in the air • Carbon backbone of organic molecules
Hydrogen • From water
Oxygen • From the air
Nitrogen • Nitrates and ammonia • Proteins, DNA, RNA, chlorophyll chlorosis
Phosphorus • From hydrogen phosphite ion • For DNA, RNA, membranes
Potassium • From K+ ions • For activation of enzymes and cellular transport
Calcium • From calcium ion • For cell walls, membrane transport
Sulfur • From sulfate ion • For proteins
Magnesium • From magnesium ion • For chlorophyll, enzyme activation
Micronutrients • Nutrients needed less than 100 mg/kg of dry mass. • B, Cl, Cu, Fe, Mn, Mo, Ni, Zn • Used for Chlorophyll synthesis, cell division, enzyme production
Temperature • Opening and closing stomata • Timing of seed germination • Timing of flowering
Soil • Medium to anchor roots • Retains water and nutrients • Air • pH