Vascular Tissue Xylem And Phloem

Vascular 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.

Similarities Both are vascular tissue (tubes) Both are found in roots, leaves and stems. Both transport materials needed by plants

Differences Xylem Phloem 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 Composed of living cells Cells don’t 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

Food Factories Leaves A leaf is an above-ground plant organ specialized for the process of photosynthesis 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.

Parts of a Leaf 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.

Transpiration 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 evaporates through stomata in leaves Water enters the roots

Importance of Transpiration Water lost by transpiration. Transpiration is necessary… for distributing water, nutrients, CO2 and O2 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) Capillary action Turgor Pressure Water absorbed by root hairs.

Leaflet Identifying Plants! The following parts of a leaf will help in identifying plants. Leaflet

petiole blade lobe

veins margin

Leaf Characteristics smooth lobed saw-toothed double saw-toothed

palmate pinnate parallel

opposite alternate

palmately compound simple pinnately compound

rounded uneven v-shaped flat heart

divided into two parts”. Dichotomous Dichotomous means “ divided into two parts”. Di = 2

offered; one will direct you to the answer and 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