Presentation on theme: "Xylem And Phloem. Vascular tissue evolved as an adaptation to life on land. It consists of a series of elements that form tubes throughout the plant."— Presentation transcript:
Xylem And Phloem
Vascular tissue evolved as an adaptation to life on land. It consists of a series of elements that form tubes throughout the plant.
Both are vascular tissue (tubes) Both are found in roots, leaves and stems. Both transport materials needed by plants
Composed of dead cells Cells are made of thick cell walls Found in wood Carries water and nutrients Transports materials up the stem…capillary action (like a straw) Helps support the stem Phloem Composed of living cells Cells dont have thick cell walls Found in bark Carries food (sugar-sap) Transports materials up and down the stem (like an elevator) Does not support the stem Xylem
Leaves A leaf is an above-ground plant organplant organ specialized for the process of photosynthesisphotosynthesis and transpiration. A leaf is typically flat and thin. As an evolutionary trait, the flatness of leaves works to expose the chloroplast to more light and to increase the absorption of carbon dioxide at the expense of water loss.
Stomata – 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.
is the evaporation of water in plants through the stomata. Transpiration takes place mainly in the underside of leaves but also occurs through roots and stems. Water travels up through xylem tubes Water enters the roots Water evaporates through stomata in leaves
Water lost by transpiration. Capillary action Water absorbed by root hairs. Turgor Pressure Transpiration is necessary… for distributing water, nutrients, CO 2 and O 2 throughout the plant. the ingredients are essential for photosynthesis and respiration. to be able to take up carbon dioxide from the atmosphere to maintain plant temperature to maintain the water cycle (10 percent of the moisture found in the atmosphere is released by plants through transpiration)
The following parts of a leaf will help in identifying plants.
saw-toothed smooth double saw- toothed lobed
parallel palmate pinnate
simple palmately compound pinnately compound
v-shaped rounded flatheart uneven
Dichotomous means divided into two parts. Di = 2
In a dichotomous key two questions are offered; one will direct you to the answer and the other will direct you to a set of two more questions. By following the key and making the correct choices, you should be able to identify the name of an unknown organism. For example…we could construct a key using the following stationary supplies taken from a student's pencil case. 1. a. long, tubular objects go to #2 1. b. short, non-tubular objects-----go to #4 2. a. constructed from plastic go to #2 2. b. constructed from wood go to #4