2Vascular tissue evolved as an adaptation to life on land Vascular tissue evolved as an adaptation to life on land. It consists of a series of elements that form tubes throughout the plant.
3Similarities Both are vascular tissue (tubes) Both are found in roots, leaves and stems.Both transport materials needed by plants
4Differences Xylem Phloem Composed of dead cells Cells are made of thickcell wallsFound in woodCarries water andnutrientsTransports materials upthe stem…capillary action(like a straw)Helps support thestemComposed of living cellsCells don’t havethick cell wallsFound in barkCarries food(sugar-sap)Transports materials upand down the stem(like an elevator)Does not support thestem
5Food Factories Leaves A leaf is an above-ground plant organ specialized for the process of photosynthesisand transpiration.A leaf is typically flat and thin.As an evolutionary trait, the flatness of leaves works toexpose the chloroplast to more light and to increasethe absorption of carbon dioxide at the expense ofwater loss.
6Parts of a LeafStomata – pores where gas exchange takes place. Guard cells – open and close the stomata to facilitate the exchange of gas and water vapor. Veins – are the xylem and phloem tubes. Cuticle – thin waxy covering of plants that prevents water loss.
7Transpiration is the evaporation of water in plants through the stomata.Transpiration takesplace mainly in theunderside of leavesbut also occursthrough roots andstems.Water travels upthrough xylemtubesWaterevaporatesthroughstomata inleavesWater entersthe roots
8Importance of Transpiration Water lost bytranspiration.Transpiration is necessary…for distributing water,nutrients, CO2 and O2throughout theplant.the ingredients are essentialfor photosynthesis andrespiration.to be able to take up carbondioxide from the atmosphereto maintain plant temperatureto maintain the water cycle(10 percent of the moisturefound in the atmosphere isreleased by plants throughtranspiration)CapillaryactionTurgor PressureWater absorbedby root hairs.
18divided into two parts”. DichotomousDichotomous means “divided into two parts”.Di = 2
19offered; one will direct you to the answer and In a dichotomous key two questions areoffered; one will direct you to the answer andthe other will direct you to a set of two morequestions. By following the key and making thecorrect choices, you should be able to identifythe name of an unknown organism.For example…we could construct a key using the followingstationary supplies taken from a student's pencil case.1. a. long, tubular objects go to #21. b. short, non-tubular objects-----go to #42. a. constructed from plastic go to #22. b. constructed from wood go to #4