Response to change

• Give 5 importance of response to change

  detection of water potential

  detection of pressure

  Detection of pathogen

  IAA in plants (light levels)

  humidity, temperature, and wind in plants
• outline detection of water potential as an importance of response to change

  water enters osmoreceptors in hypothalamus causing them to swell. hypothalamus reduces ADH which reduces the amount of aquaporins embedded in collecting ducts (less permeable to water) so less water is reabsorbed into the blood and WPT returns to normal. without this body cells would be more succeptable to lysis and loose their function e.g. less oxygen transported by haemoglobin limiting respiration and ATP production.
• outline detection of pressure as an importance of response to change

  Pacinial corpusles detect stimuli which deforms the stretch mediated Na channels, opening them. This causes sodium ions to diffuse into the axon.if the threshold is reached an action potential will occur which stimulates adjacent sodium channel to be depolarised. if this didn’t occur the CNS wouldn’t receive the impulse and produce an effect e.g. muscle contraction away from the stimuli, decreasing survival chances.
• outline pathogens as an importance for response to change

  They release antigens which can be detected by a phagocyte resulting in phagocytosis which stimulates other immune responses. This is important as it destroys the bacteria which would otherwise release harmful chemicals in our bloodstream that contain enzymes which breakdown cells and tissues making us feel ill.
• outline light levels in plants as an importance of response to change

  Plants use growth factors e.g. IAA to respond to stimuli. Phototropism is when plants respond to light and during this response IAA diffuses to shaded side of shoot to stimulate cell elongation which causes the plant to bend more towards light. This is important because it maximises light exposure which increases LDR which produces ATP and reduced NADP that is needed for the Calvin cycle Where GP is reduced to TP. and producking heroes sugars which are needed for processes such as making the plant wall. 
• outline humidity temperature and wind as an importance to response to change

  They regulate transpiration by controlling how much CO2 enters the stomata. When the guard cells are filled with water (turgid), they close and when the guard cells have limited water (flaccid) they open the stomata to allow more water and CO2 in. This prevents excessive water loss as H2O is needed for photoylsis to make atp and CO2 in the Calvin cycle to produce hexose sugars.