Plant Physiology Lecture Notes PDF

Lecture 3 Faculty of Pharmacy Pharmacognosy Dept.  Outlines 1- Revision of the last lecture 2- An introduction to plant physiology 3- Main metabolic processes 4- Transport of water, minerals and sugars 2 ...

Lecture 3 Faculty of Pharmacy Pharmacognosy Dept.  Outlines 1- Revision of the last lecture 2- An introduction to plant physiology 3- Main metabolic processes 4- Transport of water, minerals and sugars 2  Plant cell Plasma Cell wall membrane Protoplasm Golgi bodies Chloroplasts Nucleus Endoplasmic reticulum Ergastic Mitochondria Cell organelles substances Vacuole  Plant Tissues Ground Tissue Epidermis  Plant tissues Dermal Meristematic Ground Vascular Epidermis Parenchyma Collenchyma Schelrenchyma Xylem Phloem  Hairs (Trichomes) Classification Non-glandular Glandular Head Stalk Each type to be classified according to : Number of cells Type of branching Number of rows Uniseriate Unicellular Branched Biseriate Multicellular Non-branched Multiseriare Name of plant Number of Glandular or Type of Number of rows hair cells non glandular Branching Warty hair of Uni-celluar non glandular Unbranched - senna Cystolith hair of Uni-celluar non glandular Unbranched cannabis Stramonium multicellular non glandular Unbranched Uniseriate Calendula multicellular non glandular Unbranched Biseriate Twin hair in multicellular non glandular Unbranched Biseriate Arnica Shaggy hair in multicellular non glandular Unbranched multiseriate Cumin 7 Name of plant Number of Glandular or Type of Notes hair cells non glandular Branching Peltate hair in multicellular non glandular branched - Olea Candelabra hair multicellular non glandular branched in Verbascum Stellate hair in multicellular non glandular branched Tilia. Digitate hair in multicellular non glandular branched Lavender. Capitate hair Unicellular stalk Glandular Unbranched In Mentha Unicellular head Digitalis hair Unicellular stalk Glandular Unbranched Bicellular head 8 Name of plant Number of Glandular or Type of Notes hair cells non glandular Branching Clavate hair of Unicellular stalk Glandular Unbranched - stramonium Multicellular head unicellular stalk Glandular Unbranched Labiaceous hair ® & multicellular in Mentha. head with 8 -16 radiating cells. in Belladonna Multicellular stalk Glandular unbranched Uniseriate Compositae Multicellular stalk Glandular unbranched hair® in and head Chamomile Shaggy glandular Unicellular stalk Glandular Unbranched Multiseriate hair ® in Unicellular head (pluriseriate) Cannabis. 9 Glandular Multicellular stalk Glandular branched Branched hair  2- An introduction to plant physiology ▪ Plant physiology is study of the function of cells, tissues, organs of plants. “Structure correlates to function” ▪ It is also the study of metabolic processes in plants. ▪ It deals specifically with photosynthesis and respiration. 10  3- Main metabolic processes a) Photosynthesis Most important life-sustaining process. Photosynthesis is a series of processes in which solar (light) energy is converted to chemical energy in the form of a simple sugar.  Photosynthesis Chloroplasts are small membrane bound bodies inside the cell that contain the green chlorophyll pigment. Chloroplasts are the actual site where solar (light) energy is converted into stored energy- simple sugars.  Photosynthesis occurs by the fixation of carbon dioxide into carbohydrate via the following net reaction: Carbon dioxide + Water → sugars + oxygen This net reaction actually occurs via two series of interdependent reactions: light reactions and dark reactions. 13  Factors Affecting Photosynthesis Light intensity Temperature Concentration of CO2 in the atmosphere Is the limiting factor of photosynthesis process  B- Respiration The process of respiration in plants involves using the sugars produced during photosynthesis plus oxygen to produce energy for plant growth. In many ways, respiration is the opposite of photosynthesis. Plant respiration is the controlled oxidation of energy-rich photosynthetic end-products producing CO2 and adenosine triphosphate (ATP). 16  C) Nitrogen fixation cycle Nitrogen, the most abundant element in our atmosphere, is important to life because it is a key building block of DNA, which determines our genetics, is essential to plant growth, and therefore necessary for the food production. The nitrogen fixation cycle is a repeating cycle of processes during which nitrogen moves through both living and non-living things: the atmosphere, soil, water and plants. It is a process by which inert molecular nitrogen in the air is converted into its usable form which is ammonia or related nitrogenous compounds in soil. Biological nitrogen fixation converts (N2) into ammonia, which is metabolized by most organisms. 17  Nitrogen fixation is essential to life because 1-Fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing organic compounds, such as amino acids and proteins and nucleic acids. 2- It is essential for agriculture and the manufacture of fertilizer. 3- It is also, indirectly, relevant to the manufacture of all nitrogen chemical compounds. 18  All the energy required for ‘life’ processes is obtained by oxidation of macromolecules that we call ‘food’. Only green plants and cyanobacteria can prepare their own food; by photosynthesis. In green plants too, not all cells, tissues and organs photosynthesize; only cells containing chloroplasts carry out photosynthesis. Hence, all other organs, tissues and cells that are non-green, need food for oxidation. So, food has to be translocated to all nongreen parts. 20  Transport of water and minerals Water and solute need to be transported between the root system and the shoot system. Water and minerals absorbed by the roots are pulled upward in the xylem to the shoots. Sugars produced by photosynthesis exported to leaves and organs by phloem upward and downward.  Means of transport in plants According to energy, mechanisms of transportation can be divided into: Passive Transport Active Transport Doesn’t require ATP Require ATP e.g. Diffusion e.g. Bulk Transport Facilitated Diffusion i.e. Adenosine triphosphate (ATP) is an organic compound that provides energy to drive many processes in living cells. Transport in plants at Cellular level  Diffusion ‫األنتشار‬ Net movement of substance from a region of high concentration to region of low concentration. A limiting process for gases movement in plants. Considered as passive process which needs no energy (Depends on gradient).  Diffusion Factors affecting diffusion: a) Concentration Gradient: Movement from higher to lower concentration. b) Membrane permeability c) Temperature d) Pressure e) Mobility  Facilitated diffusion Membrane proteins provide sites at which such molecules cross the membrane. A concentration gradient must already be present for molecules to diffuse even if facilitated by the proteins. This process is called facilitated diffusion. No ATP needed. Movement from region of high conc. to region of low conc. Facilitated diffusion  Facilitated diffusion Some transport proteins allow diffusion only if two types of molecules move together. In a symport, both molecules cross the membrane in the same direction; in an antiport, they move in opposite directions. When a molecule moves across a membrane independent of other molecules, the process is called uniport.  Active Transport Active transport uses energy to transport and pump molecules against a concentration gradient (From low to high = ‘uphill’ transport). Active transport is carried out by specific membrane-proteins. Pumps are proteins that use energy to carry substances across the cell membrane.  Osmosis A mode of diffusion that occur through semipermeable membrane. Depends on pressure gradient and concentration gradient. It takes place from the region of high concentration of water to the region of the low concentration of water. Process continue till equilibrium. Semipermeable membrane allows only solvent to pass and not solute. Osmosis  Behavior with different solutions 1. Hypertonic solution Water conc. in the solution is less than inside the cell. Water moves from region of high conc. of water to region of low conc. of water. Cell shrinkage (Plasmolysed).  Behavior with different solutions 2. Hypotonic solution Water conc. in the solution is more than inside the cell. Water moves from region of high conc. of water to region of low conc. of water. Cytoplasm is said to be turgid.  Behavior with different solutions 3. Isotonic solution Water conc. in the solution is same as inside the cell. Water movement occur in both sides. Both movement was balanced (flaccid). Long distance transport  The xylem transfers water and mineral ions. The xylem transports water and ions to the leaf. This occurs through the process of root pressure (Pushing force) and transpiration pull (Pulling force).  Long distance transport The phloem transfers organic food material. The phloem moves glucose and amino acids away from the leaf. This occurs through the process of translocation.  Long distance transport Translocation is the movement of glucose/ sucrose and amino acids from sources to sinks through the phloem.  Long distance transport Sugars are moved by active transport from photosynthetic cells (source cells) and loaded into sieve elements of phloem and move to the cell which needs food (sink cells).  Active Transport Hypertonic soln. High Pressure Lower Pressure Hypotonic soln. Movements in plants  Movements in plants Plants show many types of movements. Movements in plants are of two main types. They are :- Tropic-Movement Nastic Movement Directional movements Non-directional reactions to towards or away from stimuli and are generally the stimulus and it connected with plants. depends on growth. Fast reaction Slower reaction Photo-tropism Geo-Tropism & Hydro-tropism Chemotropism Thigmotropism Back Phototropism It is movement of plants in response to light. If it is towards light, it is called positive phototropism. Ex:- Bending of shoot towards light. If it is away from light, it is called negative phototropism. Ex:- Bending of root away from light. Back Geotropism It is the movement of plants in response to gravity. If it is towards gravity it is called positive geotropism. Ex.:- Downward growth of roots If it is away from gravity it is called negative geotropism. Ex:- Upward growth of shoot.  Hydrotropism It is the movement of plants in response to water. Ex. :- Growth of roots towards water. Chemotropism It is movement of plant in response to chemical stimuli. Ex.:- Growth of pollen tube towards the ovule. Back Thigmotropism Directional movement ,shown by parts of plants in response to touch or physical contact with other object. It is shown by tendrils of plants. Back Thank you