LIFESCI 1 Lecture Notes - Lecture 15: Plant Cell, Cuticle, Desiccation
Document Summary
First terrestrial colonizer: animals transitioned to land after plants. Able to grow with tissues exposed to air. Dominant primary producers in terrestrial food chains. Evolutionary trends across 3 major divisions of terrestrial plants. Vacuole: are water filled organelles that contribute to the structural rigidity of plants by maintaining turgor pressure against cell walls. Vacuoles exert hydrostatic pressure on the cell walls and provide rigidity to the plant cell. Dehydration collapses vacuoles, relieves the hydrostatic pressure, and results in wilting. Cuticle: a waxy layer that prevents water loss from stems and leaves. Stomata: have pores that allow gas exchange in photosynthetic tissues. Light stimulates stomata to open (except in cam) High levels of co2 inside the leaf cause stomata to close. Turgid when filled with water, shrink when losing water & close. Low water supply-> guard cells dehydrate & shrink -> stomata close. Open stomata at night & store co2.
