Transcript CH32New2015
Plant Nutrition and transport Chapter 32 Example essay questions Describe how a plant undergoes alternation of generations. Include all the different phases that the plants go through and the processes that lead from one phase to another. Indicate which phases have the full chromosome number, and which have half the chromosome number. Compare and contrast Eukaryotic and Prokaryotic cells. More detail = more credit. Describe the reproductive and life cycle of a flowering plant. Include all phases discussed in class. More detail = more credit. Objectives • Identify the needs of plants and the entry points of materials Fig 32.1A Uptake and transport of plant nutrients • Co2 enters plants through the leaves • Water, minerals and some O2 enter through from the soil through the roots • All other materials are produced through mixtures of these • Energy is obtained from the respiration of sugars. Leaves produce O2 for this , roots absorb it from the soil • Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water Carbon dioxide • Water Glucose PHOTOSYNTHESIS Oxygen gas Respiration: glucose gives up energy as it is oxidized Loss of hydrogen atoms Energy Glucose Gain of hydrogen atoms Solute uptake in the roots Fig 32.2 Solute uptake in the roots • Roots have large surface area • Mycorrhizal fungal interactions supply nutrients and water to the plant • Substances enter roots both intracellularlly and extracellularly, control over substances occurs at the cell membrane • Intracellular (root hair membraneplasmodesmata-cortex cells, endodermal cells- xylem) • Extracellular (porous cell walls,around casparian strips, to xylem 32.11 Fungi help most plants absorb nutrients from the soil • Relationships with other organisms help plants obtain nutrients • Many plants form mycorrhizae – A network of fungal threads increases a plant's absorption of nutrients and water – The fungus receives some nutrients from the plant Figure 32.11 Transpiration Fig 32.3 Transpiration • Water – cohesion, diffusion, osmosis • How do plants lift water from the roots to the leaves • Root cell membranes pump solutes into the xylem, then water follows • Transpiration – adhesion-cohesion – Evaporation of water from leaves thru stomata – Cohesion of water molecules in the xylem – Adhesion of water to cellulose Properties of water Water is a polar molecule Water molecules stick to one Another (cohesion) and other stuff (adhesion) Fig 2.9 Fig 2.10 Transpiration is controlled by stomata Fig 32.4 Figure 32.UN05 Sugar transport Fig 32.5 Sugar transport • Phloem transports sugars • Sugars are made at “sugar sources” • Sugars travel to and are used at “sugar sinks” • Osmosis is responsible for generating pressure differences that move the sugar. • Proof ! –Aphids! Sugar sink Aphids Nutrients and plant health Fig 32.6B Macronutrients Carbon, Oxygen,Nitrogen, Hydrogen,Sulfur, Phosphorus, Calcium,Potassium, Magnesium Microinutrients Iron, zinc, etc Soil and plants Fig 32.8 32.12 Most plants depend on bacteria to supply nitrogen • The Earth’s atmosphere consists of about 80% nitrogen. – Plants cannot absorb nitrogen directly from the air. – Instead, to be used by plants, nitrogen must be converted to ammonium (NH4+) or nitrate (NO3–). Bacteria supply plants with nitrogen • Soil bacteria can convert N2 gas from into usable forms – Nitrogen-fixing bacteria nitrogen fixation: N2 to ammonia (NH3). Fig. 32.12 – Ammonifying produce ammonium. – Nitrifying bacteria convert ammonium to nitrates, the form most often taken up by plants. N2 ATMOSPHERE ATMOSPHERE Amino acids, etc. SOIL Nitrogen-fixing bacteria NH4+ H+ N2 NH3 SOIL Organic material Ammonifying bacteria NO3− NH4+ (ammonium) Nitrifying (nitrate) bacteria Root Plants have mutually beneficial symbiotic relationships • Some plants form symbioses with nitrogen-fixing bacteria. – Legumes (peas, beans, alfalfa, and others) form root nodules to house nitrogen-fixing symbionts in the genus Rhizobium.