lecture 16

• Plants are sessiles: they can’t move • they need to tolerate any bad condition whereas animals can move if there are bad conditions • plants are autotrophs: they make their own food by photosynthesis • All plants need the same things to grow

• Since there’s a lot of area in a big leaf and more stomata it can harvest more light and carbon dioxide

• High SA:V ratio is bad for plants because they overheat • To avoid overheating, its better to have low SA:V ratio • Big leaves are bad for hot environment since they lose water more because they have more stomata

• Rubisco accepts CO2 but at high temperature, it captures O2 instead of CO2 • this leads to photorespiration which produces CO2 (its meant to capture CO2 not produce), it does the opposite of what it needs to do • photorespiration is bad for the plant

• makes a 4 carbon molecule • instead of rubisco, its PEP carboxylase • this enzyme accepts CO2 and reduces photorespiration

• they save water by closing the stomata during the day so they don’t lose water • They open the stomata at night • They need to store the carbon dioxide they let in at night till the day time until they can do photosynthesis til the day time • they store the CO2 as malate

• Closing stomata • reduces waterloss • since the stomata is closed, photosynthesis cant happen and the plant stops growing • since stomata is closed, they cant do evaporative cooling and will overheat • there is a trade off between saving water and growing

• Air moves more smoothly and minimizes turbulence • Bad for plants because it prevents gas exchange

• Edges promote turbulent airflow • Good for leaf and promote gas exchange

roots move to where there’s more nutrients

• When the stomata is closed, it reduces water loss but they can’t let in co2 to do photosynthesis • Plants open and close their stomata to balance temperature and balance water

• Large leaf grow in shady places to prevent overheating • They cool by opening their stomata (evaporative cooling)