Day 11 – Transport Systems of Plants Biology 11 - Plants Day 11 – Transport Systems of Plants
Outline Growth Development of vascular tissue Xylem structure and function; transpiration pull Phloem structure and function Annular rings Textbook pp. 505-508 Study Guide pp. 49-51
New vocabulary terms (relevant to your assignment) - Meristems and apical meristems Vascular cambium Xylem and phloem (not new) Tracheids Vessel elements Casparian strip Cohesive/ cohesion Adhesive/ adhesion Capillary Action Transpiration Transpiration Pull Sieve tubes Companion cells Bulk flow Active transport Annular rings Epidermis, cortex, and pith
Growth Clusters of cells at the tips of roots and stems undergo mitosis. These clusters are called meristems. The meristem at the top of the tallest stem are called apical meristems.
Where does vascular tissue come from? Produced in the vascular cambium: meristem tissue running the length of the plant body. Tissue specializes into different types of vascular tissue, depending where it is in the plant body. Cells on the inside form xylem, cells on the outside form phloem.
Xylem Xylem cells transport water and dissolved nutrients from the root tips up to the leaves. Composed of tracheids and vessel elements. Xylem cells are dead.
Water and Xylem Water is drawn into the roots by osmosis, created by the active transport of nutrients into root cells. Water is drawn further up along a concentration gradient until it enters the xylem. Once in the xylem, it is blocked from moving back out by the Casparian strip.
Water and Xylem Water molecules are cohesive (stick together), so when water molecules evaporate out through the leaves, they pull in more water molecules to replace them. Water molecules are also adhesive, meaning they stick to other things. Cohesion and adhesion explain the phenomenon called capillary action.
Which tube is narrowest? Which tube is able to pull water highest out of the dish?
Capillary Action is not enough to bring water all the way to the top of this tree.
Transpiration Pull Transpiration is the evaporation of water from plant leaves. Water moves by osmosis into dry space, pulling water from xylem into leaves. Adhesion and cohesion pull molecules up the tubes to replace these cells. This process is called transpiration pull.
Phloem Transports sugary products of photosynthesis away from leaves to growth centres and to roots for storage. Phloem consists of sieve tubes, sieve tube plates and companion cells. Sieve tubes are the actual vessels of phloem. Companion cells help keep sieve tubes alive. Sugars are moved by bulk flow, fueled by active transport. As leaf/flower/cone cells use up sugar, more sugar flows upward by diffusion. When leaf/flower/cone cells are no longer using sugar, it flows down to the roots for storage.
Annular rings Xylem cells produced during rapid growth periods are large, while xylem cells produced during slower growth periods are smaller. Cycling through slower and faster growth periods creates rings.
Your task: Create a mind-map of all the new vocabulary terms today. To be handed in individually, okay to collaborate while creating. Use textbook, study guide, your notes, the internet, etc. Make sure all vocab terms are included and explained. Good luck! Transport