[9]Roots and Minerals Nutrition

[9]Roots and Minerals Nutrition - ROOTS AND MINERAL...

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ROOTS AND MINERAL NUTRITION (CHAPTER 35) 1. Name three important functions of a plants root. Certain opportunistic relationships with fungi and bacteria facilitate the functioning of the root. What are they and how do they help the root with its food availability? Roots o Anchors plant securely in soil o Absorbs water and dissolved minerals (e.g. Nitrates, phosphates and sulfates for synthesizing important organic molecules) For transport through plant in xylem o Storage after transport of starch and glucose in the phloem o Opportunistic relationships: Mycorrhizae facilitate uptake of essential minerals by roots Rhizobial bacteria fix N 2 in roots of leguminous plants 2. What is the difference between a taproot and fibrous root system? (Fig 35-1) Taproot System o Has one main root Formed from the radical (embryonic root) in the seeding From which many lateral roots extend (in many older trees later roots become large and produce other roots) Reach far into soil to obtain deeply located water E.g. eudicot; dandelion. Some gymnosperms Fibrous Root System o Has many adventitious roots of same size Developing from end of the stem Lateral roots branch from adventitious roots Found in plants with short lived embryonic roots In shallow soil E.g. onions, crab grass 3. Roots have the same continuous tissue system as stems and leaves; the dermal, ground, and vascular systems. For each system in the root, describe the cells and their functions and any distinguishing features (Fig 32-3) The epidermal layers of a root are not covered with a cuticle. Why? How do the cells absorb water? The cortex stores arch in which organelles? Compared to the stem, there is one type of cell that the root ground tissue does not have, and another type of cell that becomes apparent as the tissue ages. Name these. What cells occupy the vascular tissue? Primary Roots o Tissues Dermal (epidermis, roots hairs. No cuticle) Cellulose in cell walls absorb water Ground tissues (cortex(and endoderm) pith) Composed of parenchyma, amyloplast storing starch
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No supporting collenchymas but develop sclerenchyma as age Intercellular spaces (water uptake and aeration) Vascular tissues (xylem and phloem) 4. The root cap is the protective layer that covers the root tip. It also covers and protects another dedifferentiated tissue. Name the tissue. (Fig 35-2) If the root cap is removed, what would happen to the root growth? How does the root reduce the inevitable friction to the root cap cells as it burrows down into the soil? Structures 1 o Roots cap Protective layer that covers the root tip As covers delicate root apical meristem As roots moves through sol, cells sloughed off are replaced by new from root apical meristem May orient root s so that it grows downward Will grow randomly if removed Roots cap cells secrete lubricating polysaccharide reducing friction as roots passes through soil
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[9]Roots and Minerals Nutrition - ROOTS AND MINERAL...

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