Homeostasis its control mechanism
- 1. HOMEOSTASIS & ITS CONTROL MECHANISM. PRESENTED BY : R A SH MI JA LA N
- 2. Theterm wascoined in1930bythe physician WalterCannon. Homeostasis is thetendency toresist change inorder tomaintain astable, relatively constant internal environment. Homeo – ‘stable’ ; stasis – ‘standing’. The pathway of homeostasis is different for bothPlants and Animals.
- 3. o Plant health depends upon availability of water, air, light and nutrient. o Regulation and coordination systems in plants are much simpler than in animals andplants are highly phenotypically plastic. o As plant has no nervous system; Stomata , Transport system, various kind of Gradient, Hormones performs the all internal homeostaticmechanism.
- 4. 1. OSMOREGULATION IN PLANTS The regulatory mechanismwhich maintain the balance between water and solute context of a cell is called osmoregulation. The chief organ involved in osmoregulation is Stomata, whose opening and closing is regulated by guardcell.
- 5. Stomata – Stomata are generally abundant on the surfaces of leaves, more commonly on the underside. – Stomatal pores in the epidermis are bounded by two highly specialised guard cells. Guard Cells – Guard cells have three structural features which explain their function: They are joined at their ends in pairs Their cell walls are thicker on the side nearest to the stomatal pore Bands of inelastic cellulose fibres run around each cell
- 6. Regulating Stomata – Stomata movement is the result of changes in the turgor of the guard cells. – If water flows into the guard cells by osmosis, their turgor increases and they expand. The relatively inelastic inner wall makes them bend and draw away from each other. This opens the pore. Stomatal Opening 1.Potassium ions move into the vacuoles. 2.Water moves into the vacuoles, following potassium ions. 3.The guard cells expand. 4.The stoma opens. Stomatal Closing 1.Potassium ions move out of the vacuole and out of the cells. 2.Water moves out of the vacuoles, following potassium ions. 3.The guard cells shrink in size.
- 8. 2. THERMOREGULATION IN PLANTS• The maintained the temperature of the body within a range is called thermoregulation. The normal range of temperature in plant is 10˚C to 35˚C. The adaption of plant to low and high temperature are as follows. Low Temperature At low temperature the nature of plasma membrane is changed and produce crystalline structure called antifreeze protiens and dehyrins due to which transport of solute is slow. At low temperature plant cell produce unsaturated fatty acid in cell membrane and become gel like. At freezing point ice crystal are formed in the cell. But the plant of cold region change the composition of solute of cell so ice crystal are not formed in cytoplasm they form in cell wall. This condition is known as freezing tolerance.
- 9. High Temperature High temperature has more harmful than low temperature for plant. Due to high temperature all enzyme are denature and metabolic process stop. So plant increase rate of transpiration and cool the body. At above 40ºC plant produce heat shock protein. They protect the enzyme from destroying. In some plant shiny cuticle is present which protest them from high temperature. In some plant leaves are reduce in size. The cell produces saturated fatty acids in cell membrane and the cell become leaky.
- 10. 3. EXCREATION IN PLANTS The removal of harmful substance produce in the metabolic process fromthe body is called Excretion. Excretion in Plant In plant rate of catabolic process is very slow and waste product are produce in less amount. They are used again in their anabolic process. Waste Substance of Plant The substance which are produce in excess amount are 1. Water 2. CO2 3. O2 4. Ions
- 11. •Transpiration The extra amount of water removed in the form of vapor through stomata is called transpiration. 1. Removal of Water Extra water is removed from the body of plant by two methods. •Guttation When water is removed from plant in the form of drop this process is called Guttation. Guttation occur special opening called hydathods. Guttation take place in those plant which grow in tropical rain forest.
- 12. 3. Ions Excess amount of ion are deposit into dead cell of plant body such as bark. 2. Release of Oxygen and Carbon dioxide In day time plant used CO2 for photosynthesis process and released O2. In night time plant released CO2 and inhale O2 gas.
- 13. Some astonishing homeostasis phenomenon in plants Pyriscence, where maturation and release of seeds is triggered, in whole or in part, by fire or smoke; this behaviour is often erroneously called serotiny. Some species, such as Macroptilium purpureum, can move their leaves throughout the day so that they are always orientated to avoid the sun (paraheliotropism). Raoulia plants found in the uplands of New Zealand are said to resemble ‘vegetable sheep’ as they form tight cushion-like clumps to insulate the most vulnerable plant parts and shield them from cooling winds. Plants can sense the wind through the deformation of its tissues. This signal leads to inhibits the elongation and stimulates the radial expansion of their shoots, while increasing the development of their root system. This syndrome of responses known as thigmomorphogenesis results in shorter, stockier plants with strengthened stems, as well as to an improved ancorag
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