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Transport in plants

Monocots and dicots are classified based on the number of seed leaves, with monocots having one and dicots having two. They differ in various structural aspects including leaf vein patterns, floral parts, and root systems. Additionally, the document discusses the vascular tissue organization in stems and roots, explaining how water and nutrients are transported within plants.

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Monocots and Dicots • Monocots and dicots are named for the number of seed leaves, or cotyledons, in the plant embryo. • Monocots have one seed leaf, and dicots have two seed leaves Monocotyledonous plants: grass,grass, lilies, orchids, and palm treeslilies, orchids, and palm trees Dicotyledonous plants: Roses,Roses, oaks, sunflowersoaks, sunflowers
http://www.youtube.com/watch? v=4uq5ybc4vts&feature=related Watch the video clip!
– single seed leaf (cotyledon) – flowers/petals grow in groups of three – leaves have parallel veins Monocots
• Flowers often small • Usually grow for only one year • Examples: corn, grasses, onions, lilies and many grains
Dicots –two seed leaves (cotyledons) –flowers/petals grow in groups of four or five –leaves have network veins that branch out
Examples: trees, sunflower,Examples: trees, sunflower, beans, pumpkins and cloverbeans, pumpkins and clover.. Greatest number of plants are dicots Tend to live a long time – one season or many Produce food, clothing, housing
Monocots vs. Dicots Parallel leaf veinsParallel leaf veins Net-like leaf veinsNet-like leaf veins
Monocots vs. Dicots Floral Parts in 3’sFloral Parts in 3’s Floral Parts in 4’s or 5’sFloral Parts in 4’s or 5’s
Monocots vs. Dicots Vascular TissueVascular Tissue ScatteredScattered Vascular tissue in ringsVascular tissue in rings
Monocots vs. Dicots Fibrous root systemFibrous root system Taproot SystemTaproot System
Monocots Verses Dicots Floral Parts in 3’sFloral Parts in 3’s Floral Parts in 4’s or 5’sFloral Parts in 4’s or 5’s Parallel leaf veinsParallel leaf veins Net-like leaf veinsNet-like leaf veins Fibrous root systemFibrous root system Taproot SystemTaproot System Vascular TissueVascular Tissue ScatteredScattered Vascular tissue in ringsVascular tissue in rings Includes: grass, lilies,Includes: grass, lilies, orchids, and palm trees.orchids, and palm trees. Includes: Roses, oaks,Includes: Roses, oaks, sunflowers and most non-sunflowers and most non- conifer trees.conifer trees.
Vascular bundles Leaf Stem Root Xylem Xylem Phloem Xylem Phloem Phloem
Vascular bundle • A strand of tissue that carry water and nutrients through the body of the plant Xylem Phloem
Xylem on the inside and phloem on the outside, separated by cambium
Xylem • Carry water and dissolved mineral salts upwards from the roots to every part of the plant • Provide mechanical support for the plant
Hollow vessels (cells without cross-walls) Walls are thickened and strengthened with lignin Water and mineral transport Mechanical support Xyle m Structures At maturity, dead tissue → wood
Different patterns of lignification
Adaptations •Having a continuous lumen without any protoplasm within to prevent the flow of water and mineral salts •Having lignified walls which prevent collapse of the vessels Xyle m
Phloem • Transports nutrients (sugars and amino acids) from the leaves to other parts of the plant
Phloem Structures • Consists of a column of sieve tubes (elongated, thin-walled living cells) and companion cells • Sieve tubes are separated by sieve plates (cross-walls separating the cells perforated by minute pores Phloem
• The sieve tube cells are perforated to enable food substances to pass through them to be transported to various parts of the plant • Companion cells have many mitochondria to load sugars from mesophyll cells into sieve tubes by active transport Phloem Adaptations
Xylem Phloem Consists of dead cells Consists of living cells -Transports water and mineral salts -Provide mechanical support to the plant Transports sugar and amino acids Transport is unidirectional Transport – directional, upwards and downwards Substances are transported by passive transport - osmosis, root pressure, capillary action, transpiration pull Substances are transported by active transport, diffusion
Organization of vascular tissue in Stem 1. Vascular Bundle The xylem and phloem are grouped together to form the vascular bundles
Organization of vascular tissue in Stem 1. Vascular Bundle 2. Cambium Cambium cells can divide to give rise to new xylem and phloem tissues, hence thickening of the stem Phloem Cambium Xylem
Organization of vascular tissue in Stem 1. Vascular Bundle 2. Cambium The vascular bundles are arranged in a ring surrounding a central region called pith which serves as a storage tissue for food substances 3. Pith
Organization of vascular tissue in Stem 1. Vascular Bundle 2. Cambium The region between the vascular bundles and epidermis is the cortex, which also serves as a storage tissue for food substances 3. Pith 3. Cortex
Organization of vascular tissue in Stem 1. Vascular Bundle 2. Cambium The epidermal cells are covered with a layer of wax called cuticle which prevents excessive loss of water from the stem 3. Pith 4. Cortex 5. Epidermis
Organization of vascular tissue in Stem 1. Vascular Bundle 2. Cambium 3. Pith 4. Cortex 5. Epidermis Phloem Cambium Xylem
Root Functions •Anchor the plant •Specialized in absorption of water & dissolved minerals
Vascular Bundles in Roots Cross-section of a dicotyledonous root
Organization of vascular tissue in Root 1.Vascular Tissue xylem phloem The xylem and phloem are NOT bundle together. They alternate with each other
1. Vascular Tissue The region between the epidermis and the endodermis lies the Cortex, which serves as storage tissue 2.Cortex Endodermis Organization of vascular tissue in Root
1. Vascular Tissue The epidermis of the root bearing the root hairs are called the piliferous layer. NO cuticle is present! 2. Cortex 3.Piliferous layer Organization of vascular tissue in Root
1. Vascular Tissue Each root hair is a tubular outgrowth of an epidermal cell. 2. Cortex 3. Piliferous layer 4.Root hair Organization of vascular tissue in Root
1. Vascular Tissue 2. Cortex 3. Piliferous layer 4. Root hair xylem phloem Organization of vascular tissue in Root
What are the adaptations of Root? * Long and narrow  Increase surface area to volume ratio * Cells are alive  Provide energy for active transport * Root hairs have cell sap of higher concentration than surrounding soil solution  Cell sap contains sugar, mineral salts which helps to prevent water leaking out of cell. Assist in osmosis
Root Stem Leaves Transpor t of water
How does water move through the transport system of a plant if it does not have a heart to act as a pump? Think Like a Scientist How is water lifted against gravity from the ground to the leaves through this transport system?
cytoplasm vacuole nucleus cell wall cell surface membrane of root hair cell film of liquid (dilute solution of mineral salts) soil particles Entry of Water through the roots
Entry of Water through the roots The sap in the root hair cell is a relatively concentrated solution of sugars and various salts. Thus, the sap has a lower water potential than the soil solution. These two solutions are separated by the partially permeable cell surface membrane of the root hair cell. Water enters the root hair by osmosis. AB C xylem phloem cortex root hair piliferous layer water entering the root hair
Entry of water through the roots • Water enters the roots through the root hairs. • Sap of root hair cells has a higher concentration of sugars and salts. Its is very concentrated. • Since the surrounding soil particles has a high water potential, water enters the root hair from the soil through osmosis.
Entry of mineral salts through the roots * Diffusion –when the concentration of minerals salts in the soil solution is higher than that in the root hair cell. * Active transport –when the concentration of ions in the soil solution is lower than that in the root hair cell sap. * The energy comes from cellular respiration in the root hair cells
Moving water up the stem • Root pressure • Capillary action • Transpiration pull
• By using active transport, ions in the living cells around the xylem vessels in the root are pumped into the vessels. • Water potential in the xylem vessels is lowered. • Water passes from the living cells into the xylem vessels by osmosis and flows upwards. Root pressure
Capillary action
• Water molecules attract other water molecules by the force of cohesion. • Water sticks to the inner surface of the xylem vessels by adhesion. • The water moves up the plant into the leaves. Capillary action
• Transpiration is the loss of water vapour from the leaves, especially through the stomata. • The suction force caused by transpiration is called transpiration pull. • The stream take the water moves up the plant is called transpiration stream. Transpiration pull
Question 1 The root of a flowering plant absorbs water and mineral ions mainly through … (d) the xylem (c) the phloem (b) the root hairs (a) the epidermis Question 2
The epidermis is largely impermeable except in the region where root hairs develop No
Transverse section through a root root hair epidermis phloem xylem 0.05 mm Root hair cell root hair Yes The root hairs are extensions from some of the epidermal cells. They have very thin cell walls and absorb water and mineral ions.
No The phloem conducts sugars and amino acids to the root but is not involved in the uptake of water
No The xylem carries water from the root to the rest of the plant but it is not the structure involved in the entry of water
Question 2 The force responsible for water travelling up a tree is generated mainly by … (d) osmosis (c) active transport (b) root pressure (a) evaporation from the leaves
Yes Evaporation of water from the leaves creates a tension which draws water up the trunk evaporation
No Root pressure can force water some distance up the trunk but is insufficient to take it all the way
No Active transport enables the roots to take up dissolved substances against a diffusion gradient. It is not responsible for the flow of water up the trunk
No Osmosis generates root pressure but this is insufficient to force water all the way up the trunk
Transpiration is the loss of water vapour from the leaves, especially through the stomata The suction force caused by transpiration is called transpiration pull The stream take the water moves up the plant is called transpiration stream
Stomata • When stomata are open, evaporation draws water out of the leaf. Gas exchange can also occur to keep photosynthesis and respiration running.
Transpiration pull draws water and mineral salts from the roots to the stems and leaves.  Evaporation of water from the cells in the leaves removes latent heat of vaporisation. This cools the plant, preventing it from being scorched by the hot sun.  Water transported to the leaves can be used in the photosynthesis; - to keep cells turgid - to replace water lost by the cell Turgid cells keep the leaves spread out widely to trap sunlight for photosynthesis. Importance of TRANSPIRATION
1.1. TemperatureTemperature Increases  Increases transpiration rate 1.1. Air humidityAir humidity Increases  Decreases transpiration rate 1.1. Light intensityLight intensity Increases  Increases transpiration rate 1.1. WindWind Increases  Increases transpiration rate 1.1. Water supplyWater supply Decreases  Decreases transpiration rate 5 Factors that affect Transpiration
Temperature The higher the temperature, the higher the air water capacity to hold moisture At 30ºC, a leaf may transpire 3 times as fast as it does at 20ºC
Light intensity During the day, stomata of the leaves open. Why? Photosynthesis!! Gases exchange (CO2 & O2) Water vapor also evaporates (Transpiration)