Introductory Biology III

Introductory Biology III
BIOL 100C: Introductory Biology III Soils & Minerals; Water Transport Dr. P. Narguizian Fall 2012 Principles of Biology

Planting Hope in the Wake of Katrina
Many plants can remove toxins such as heavy metals from soils by taking them up with their roots and storing them in their bodies The use of plants to clean up polluted soil and groundwater is called phytoremediation Copyright © 2009 Pearson Education, Inc.

Planting Hope in the Wake of Katrina
Concerns associated with phytoremediation include Release of toxins into the air via evaporation from plant leaves Disposal of plants with high concentrations of pollutants Possible toxicity to animals that eat plants with high concentrations of pollutants Copyright © 2009 Pearson Education, Inc.

Sunflowers after flooding.

THE UPTAKE AND TRANSPORT OF PLANT NUTRIENTS
THE UPTAKE AND TRANSPORT OF PLANT NUTRIENTS Copyright © 2009 Pearson Education, Inc.

Plants acquire their nutrients from soil and air
Plants take up carbon dioxide from the air to produce sugars via photosynthesis; oxygen is produced as a product of photosynthesis Plants obtain water, minerals, and some oxygen from the soil Using simple sugars as an energy source and as building blocks, plants convert the inorganic molecules they take up into the organic molecules of living plant tissue Teaching Tips 1. Module 32.1 references the discussion of photosynthesis in Chapter 7. If you have not already addressed the content of Chapter 7, consider discussing the sources of carbon, hydrogen, and oxygen that are used in the construction of carbohydrates resulting from photosynthesis. 2. With the exception of small amounts of glycogen obtained from meat and lactose obtained from dairy products, we humans get all of our dietary carbohydrates from plants. Copyright © 2009 Pearson Education, Inc.

32.1 Plants acquire their nutrients from soil and air
Inorganic molecules taken up by plants Carbon dioxide Nitrogen Magnesium Phosphorus Teaching Tips 1. Module 32.1 references the discussion of photosynthesis in Chapter 7. If you have not already addressed the content of Chapter 7, consider discussing the sources of carbon, hydrogen, and oxygen that are used in the construction of carbohydrates resulting from photosynthesis. 2. With the exception of small amounts of glycogen obtained from meat and lactose obtained from dairy products, we humans get all of our dietary carbohydrates from plants. Copyright © 2009 Pearson Education, Inc.

Plants acquire their nutrients from soil and air
Organic molecules produced by plants Carbohydrates Lipids Proteins Nucleic acids Teaching Tips 1. Module 32.1 references the discussion of photosynthesis in Chapter 7. If you have not already addressed the content of Chapter 7, consider discussing the sources of carbon, hydrogen, and oxygen that are used in the construction of carbohydrates resulting from photosynthesis. 2. With the exception of small amounts of glycogen obtained from meat and lactose obtained from dairy products, we humans get all of our dietary carbohydrates from plants. Copyright © 2009 Pearson Education, Inc.

CO2 Figure 32.1A The uptake of nutrients by a plant. Minerals O2 H2O

The plasma membranes of root cells control solute uptake
Minerals taken up by plant roots are in a watery solution Water and minerals are absorbed through the epidermis of the root and must be taken up by root cells before they enter the xylem Selective permeability of the plasma membrane of root cells controls what minerals enter the xylem Teaching Tips 1. Root hairs are yet another example of an adaptation to increase the surface area of an organism. The divisions within the human lung, as well as microvilli, and plant leaves, are other examples. Increased surface areas are typically found where something is exchanged: gases exchanged at respiratory surfaces, nutrients absorbed by microvilli, light absorbed by leaves, and water and minerals absorbed by root hairs. If this chapter is one of the final topics addressed in your course, illustrating these broad principles with examples from a variety of subjects can provide a unifying review. Copyright © 2009 Pearson Education, Inc.

There are two pathways by which water and minerals enter the xylem Intracellular route—water and solutes are selectively taken up by a root epidermal cell, usually a root hair, and transported from cell to cell through plasmodesmata Extracellular route—water and solutes pass into the root in the porous cell walls of root cells; they do not enter any cell plasma membrane until they reach the root endodermis Teaching Tips 1. Root hairs are yet another example of an adaptation to increase the surface area of an organism. The divisions within the human lung, as well as microvilli, and plant leaves, are other examples. Increased surface areas are typically found where something is exchanged: gases exchanged at respiratory surfaces, nutrients absorbed by microvilli, light absorbed by leaves, and water and minerals absorbed by root hairs. If this chapter is one of the final topics addressed in your course, illustrating these broad principles with examples from a variety of subjects can provide a unifying review. Copyright © 2009 Pearson Education, Inc.

The cells of the endodermis contain a waxy barrier called the Casparian strip Water and solutes that have entered the root without crossing a cell plasma membrane are blocked Specialized cells of the endodermis take up water and minerals selectively The Casparian strip regulates uptake of minerals that enter the root via the extracellular route Teaching Tips 1. Root hairs are yet another example of an adaptation to increase the surface area of an organism. The divisions within the human lung, as well as microvilli, and plant leaves, are other examples. Increased surface areas are typically found where something is exchanged: gases exchanged at respiratory surfaces, nutrients absorbed by microvilli, light absorbed by leaves, and water and minerals absorbed by root hairs. If this chapter is one of the final topics addressed in your course, illustrating these broad principles with examples from a variety of subjects can provide a unifying review. Copyright © 2009 Pearson Education, Inc.

Figure 32.2B Routes of water and solutes from soil to root xylem.
Root hair Epidermis Cortex Phloem Key Dermal tissue system Ground tissue system Vascular tissue system Casparian strip Xylem Endodermis Extracellular route, via cell walls; stopped by Casparian strip Casparian strip Xylem Root hair Figure 32.2B Routes of water and solutes from soil to root xylem. Plasmodesmata Intracellular route, via cell interiors, through plasmodesmata Epidermis Endodermis Cortex

Key Root hair Epidermis Cortex Phloem Casparian strip Xylem Endodermis
Dermal tissue system Ground tissue system Vascular tissue system Figure 32.2B Routes of water and solutes from soil to root xylem. Casparian strip Xylem Endodermis

Casparian strip Extracellular route, Xylem via cell walls; stopped by
Root hair Plasmodesmata Intracellular route, via cell interiors, through plasmodesmata Figure 32.2B Routes of water and solutes from soil to root xylem. Epidermis Endodermis Cortex

Transpiration pulls water up xylem vessels
Xylem sap is the solution carried up through a plant in tracheids and vessel elements Xylem sap is pulled up through roots and shoots to the leaves Evaporation of water from the surface of leaves, called transpiration, is the driving force for the movement of xylem sap Water’s cohesion and adhesion allow water to be pulled up to the top of the highest trees Teaching Tips 1. The cohesive property of water allows some insects to walk or stand on a liquid water surface. The cohesion and adhesion of water is also the reason why we need to dry ourselves off after taking a shower, since water still clings to our skin and hair. 2. Demonstrate or ask students to recall what happens when a soda straw is lifted out of a beverage: some of the beverage still sticks to the straw. This is an example of adhesion. Copyright © 2009 Pearson Education, Inc.

Transpiration pulls water up xylem vessels
Transpiration-cohesion-tension mechanism Water’s cohesion describes its ability to stick to itself Water’s adhesion describes its ability to stick to other surfaces; water adheres to the inner surface of xylem cells A steep diffusion gradient pulls water molecules from the surface of leaves into much drier air The air’s pull on water creates a tension that pulls on water in the xylem; since water is cohesive, it is pulled along, much as when a person sucks on a straw For the BioFlix Animation Transpiration, go to Animating and Video Files. Teaching Tips 1. The cohesive property of water allows some insects to walk or stand on a liquid water surface. The cohesion and adhesion of water is also the reason why we need to dry ourselves off after taking a shower, since water still clings to our skin and hair. 2. Demonstrate or ask students to recall what happens when a soda straw is lifted out of a beverage: some of the beverage still sticks to the straw. This is an example of adhesion. Copyright © 2009 Pearson Education, Inc.

Transpiration (regulated by guard cells surrounding stomata) H2O Cohesion and adhesion in xylem Flow of water (cohesion of H2O molecules to each other and adhesion of H2O molecules to cell walls) Water uptake (via root hairs) H2O

Xylem sap Mesophyll cells Air space within leaf Stoma Outside air
1 Outside air Transpiration Flow of water Figure 32.3 The flow of water up a tree.

1 Outside air Transpiration Water molecule Flow of water 2 Cohesion by hydrogen bonding Xylem cells Cohesion in the xylem Figure 32.3 The flow of water up a tree.

1 Outside air Transpiration Water molecule Flow of water 2 Cohesion by hydrogen bonding Xylem cells Cohesion in the xylem Figure 32.3 The flow of water up a tree. 3 Root hair Soil particle Water Water uptake from soil

Cohesion and adhesion in the xylem
Xylem sap Mesophyll cells Air space within leaf Stoma 1 Outside air Adhesion Transpiration 4 Cell wall Water molecule Flow of water 2 Cohesion by hydrogen bonding Xylem cells Cohesion and adhesion in the xylem Figure 32.3 The flow of water up a tree. 3 Root hair Soil particle Water Water uptake from soil

Guard cells control transpiration
Plants must open pores in leaves called stomata to allow CO2 to enter for photosynthesis Water evaporates from the surface of leaves through stomata Paired guard cells surround each stoma Guard cells can regulate the amount of water lost from leaves by changing shape and closing the stomatal pore Teaching Tips 1. The change in shape of guard cells is due to internal fluid pressure, or turgor—important in many other organisms. Turgor helps maintain the shape of plant cells, gives structure to the hydrostatic skeletons of sea anemones and earthworms, and causes a penis to become firm upon erection. Before addressing guard cells, you may challenge your class to explain what leaves, earthworms, and an erect penis have in common. The answer is turgor. Copyright © 2009 Pearson Education, Inc.

Stomata open when guard cells take up water Potassium is actively taken up by guard cells from nearby cells This creates an osmotic gradient and water follows Uneven cell walls of guard cells causes them to bow when water is taken up The bowing of the guard cells causes the pore of the stoma to open When guard cells lose K+ ions, the guard cells become flaccid and the stoma closes Teaching Tips 1. The change in shape of guard cells is due to internal fluid pressure, or turgor—important in many other organisms. Turgor helps maintain the shape of plant cells, gives structure to the hydrostatic skeletons of sea anemones and earthworms, and causes a penis to become firm upon erection. Before addressing guard cells, you may challenge your class to explain what leaves, earthworms, and an erect penis have in common. The answer is turgor. Copyright © 2009 Pearson Education, Inc.

H2O H2O H2O H2O H2O H2O K+ H2O H2O H2O H2O Stoma Guard cells Vacuole
Figure 32.4 How guard cells control stomata. Vacuole H2O H2O H2O H2O Stoma opening Stoma closing

Several factors help regulate guard cell activity In general, stomata are open during the day and closed at night Sunlight signals guard cells to accumulate K+ and open stomata Low CO2 concentration in leaves also signals guard cells to open stomata Plants have natural rhythms that help them close stomata at night to conserve water Plants may also close stomata during the day to conserve water when necessary Teaching Tips 1. The change in shape of guard cells is due to internal fluid pressure, or turgor—important in many other organisms. Turgor helps maintain the shape of plant cells, gives structure to the hydrostatic skeletons of sea anemones and earthworms, and causes a penis to become firm upon erection. Before addressing guard cells, you may challenge your class to explain what leaves, earthworms, and an erect penis have in common. The answer is turgor. Copyright © 2009 Pearson Education, Inc.

Phloem transports sugars
Phloem transports the products of photosynthesis throughout the plant Phloem is composed of long tubes of sieve tube members stacked end to end Phloem sap moves through sieve plates in sieve tube members Phloem sap is composed of sucrose and other solutes such as ions, amino acids, and hormones Sugars are carried through phloem from sources to sinks Student Misconceptions and Concerns 1. Although analogies are often useful, some of their particulars can be misleading. In many ways, the vascular tissues and movement of fluid through plants are unlike the circulatory system of vertebrates. Whereas vertebrates have a one-way flow of fluids propelled by a contracting heart through a contained tubular system, phloem sap, propelled instead by a pressure flow mechanism, can move in either direction. Teaching Tips 1. Many phloem saps other than maple syrup are used commercially. For example, phloem sap from rubber trees native to the Brazilian Amazon was once the major source of rubber. (Most rubber is now synthetically produced.) Pine oil, derived from pine tree resin, is the active ingredient in Pine-Sol cleaner. Copyright © 2009 Pearson Education, Inc.

Sieve- tube member Sieve plate
Figure 32.5A Food-conducting cells of phloem.

A sugar source is a plant organ that is a net producer of sugar via photosynthesis or breakdown of starch Leaves produce sugars via photosynthesis Roots and other storage organs produce sugar via breakdown of starch A sugar sink is a plant organ that is a net consumer of sugar or one that stores starch Growing organs use sugar in cellular respiration Roots and other organs store unused sugars as starch Student Misconceptions and Concerns 1. Although analogies are often useful, some of their particulars can be misleading. In many ways, the vascular tissues and movement of fluid through plants are unlike the circulatory system of vertebrates. Whereas vertebrates have a one-way flow of fluids propelled by a contracting heart through a contained tubular system, phloem sap, propelled instead by a pressure flow mechanism, can move in either direction. Teaching Tips 1. Many phloem saps other than maple syrup are used commercially. For example, phloem sap from rubber trees native to the Brazilian Amazon was once the major source of rubber. (Most rubber is now synthetically produced.) Pine oil, derived from pine tree resin, is the active ingredient in Pine-Sol cleaner. Copyright © 2009 Pearson Education, Inc.

The pressure flow mechanism At sources, sugars are actively loaded into sieve tube members High solute concentration caused by the sugar in sieve tubes causes water to rush in from nearby xylem cells Flow of water into sieve tubes increases pressure at sources At sinks, sugars are unloaded from sieve tubes and solute concentration decreases; water is lost and pressure is low The pressure gradient drives rapid movement of sugars from sources to sinks Student Misconceptions and Concerns 1. Although analogies are often useful, some of their particulars can be misleading. In many ways, the vascular tissues and movement of fluid through plants are unlike the circulatory system of vertebrates. Whereas vertebrates have a one-way flow of fluids propelled by a contracting heart through a contained tubular system, phloem sap, propelled instead by a pressure flow mechanism, can move in either direction. Teaching Tips 1. Many phloem saps other than maple syrup are used commercially. For example, phloem sap from rubber trees native to the Brazilian Amazon was once the major source of rubber. (Most rubber is now synthetically produced.) Pine oil, derived from pine tree resin, is the active ingredient in Pine-Sol cleaner. Copyright © 2009 Pearson Education, Inc.

High sugar concentration Phloem Xylem High water pressure Sugar Sugar
1 High water pressure Sugar Sugar source 2 Water Source cell Sieve plate Sugar sink Sink cell Figure 32.5B Pressure flow in plant phloem from a sugar source to a sugar sink (and the return of water to the source via xylem). 3 Sugar 4 Water Low sugar concentration Low water pressure

Aphid feeding on a small branch Aphid’s stylet inserted into
of aphid Honeydew droplet Figure 32.5C Tapping phloem sap with the help of an aphid. Aphid feeding on a small branch Aphid’s stylet inserted into a phloem cell Severed stylet dripping phloem sap

PLANT NUTRIENTS AND THE SOIL
PLANT NUTRIENTS AND THE SOIL Copyright © 2009 Pearson Education, Inc.

Plant health depends on a complete diet of essential inorganic nutrients
Essential elements are those that a plant must obtain to complete its life cycle of growth and reproductive success There are 17 elements essential to plant growth and reproduction Macronutrients—plants require relatively large amounts of these elements Micronutrients—plants require relatively small amounts of these elements Both types of nutrients have vital functions It is important to distinguish between the acquisition of nutrients and the acquisition of food. Plants do not obtain their food from the environment, like animals. Instead, plants are autotrophs that generate their own food. The essential elements required by plants are not sources of calories. Students might suspect that macronutrients are large and micronutrients are small. Instead, the word roots macro- and micro- refer to the quantities of nutrients required in each category. Student Misconceptions and Concerns 1. Students often confuse the terms symbiosis and mutualism, falsely thinking that they mean the same thing. You might wish to clarify these terms to emphasize the win/win nature of mutualism. Teaching Tips 1. With abundant antibacterial products now on the market, students may believe that all bacteria are harmful. Before addressing the mutualistic roles of soil bacteria and plants, challenge your students to explain why planting seeds in sterilized soil could be problematic. Copyright © 2009 Pearson Education, Inc.

Plant health depends on a complete diet of essential inorganic nutrients
Macronutrients—components of organic molecules Carbon Hydrogen Oxygen Nitrogen Sulfur Phosphorus Potassium Calcium Magnesium Micronutrients—often act as cofactors Chlorine Iron Manganese Boron Zinc Copper Nickel Molybdenum Make up 98% of plant dry weight Student Misconceptions and Concerns 1. Students often confuse the terms symbiosis and mutualism, falsely thinking that they mean the same thing. You might wish to clarify these terms to emphasize the win/win nature of mutualism. Teaching Tips 1. With abundant antibacterial products now on the market, students may believe that all bacteria are harmful. Before addressing the mutualistic roles of soil bacteria and plants, challenge your students to explain why planting seeds in sterilized soil could be problematic.

Complete solution containing all minerals (control) Solution lacking
Figure 32.6 A hydroponic culture experiment. Complete solution containing all minerals (control) Solution lacking potassium (experimental)

CONNECTION: Fertilizers can help prevent nutrient deficiencies
The availability of nutrients in soil affects plant growth and health Growers can often determine which nutrients are missing from soil by looking at plant symptoms Nutrient deficiencies can be alleviated by adding inorganic chemical fertilizers or compost to soil Nitrogen is the element that most commonly limits plant growth in nature Student Misconceptions and Concerns 1. Students often confuse the terms symbiosis and mutualism, falsely thinking that they mean the same thing. You might wish to clarify these terms to emphasize the win/win nature of mutualism. Teaching Tips 1. Students who know that most (78%) of Earth’s atmosphere consists of nitrogen may be confused to learn that nitrogen shortage is the most common nutritional problem for plants. As Modules 32.7 and indicate, plants cannot use nitrogen in its most common form, which is found in the atmosphere. However, they can use dissolved nitrate ions and ammonium ions. Copyright © 2009 Pearson Education, Inc.

Figure 32.7A The effect of nitrogen availability on corn growth: corn grown in nitrogen-rich soil (left) and nitrogen-poor soil (right).

Figure 32.7B Nitrogen deficiency in a tomato leaf.
Figure 32.7C Steam produced by the metabolic activity of organisms within a compost pile.

Fertile soil supports plant growth
Soils are affected by geography and climate Soil horizons are layers of soil with different characteristics A horizon—topsoil subject to weathering; layer contains humus (decayed organic matter) and many soil organisms B horizon—clay and dissolved elements C horizon—rocks of the “parent material” from which soil is formed Student Misconceptions and Concerns 1. Students often confuse the terms symbiosis and mutualism, falsely thinking that they mean the same thing. You might wish to clarify these terms to emphasize the win/win nature of mutualism. Teaching Tips 1. Students with limited backgrounds in botany might be surprised to learn that roots need oxygen. Aeration of the soil by burrowing worms and other animals helps create small spaces for air. Highly compacted soils limit the movement of air and can interfere with plant survival. Copyright © 2009 Pearson Education, Inc.

A B Figure 32.8A Three soil horizons visible beneath grass. C

Fertile soil supports plant growth
A soil’s physical and chemical characteristics affect plant growth Soil particle sizes influence the amount of water and air present in a soil Soil particles and plant roots participate in cation exchange—the transfer of positive ions such as calcium, magnesium, and potassium from soil to plant roots Soil particles tend to bond cations and can make uptake by plants difficult Anions are readily taken up by plants and not affected as much by soil Student Misconceptions and Concerns 1. Students often confuse the terms symbiosis and mutualism, falsely thinking that they mean the same thing. You might wish to clarify these terms to emphasize the win/win nature of mutualism. Teaching Tips 1. Students with limited backgrounds in botany might be surprised to learn that roots need oxygen. Aeration of the soil by burrowing worms and other animals helps create small spaces for air. Highly compacted soils limit the movement of air and can interfere with plant survival. Copyright © 2009 Pearson Education, Inc.

Soil particle surrounded by film of water
Root hair Water Figure 32.8B A close-up view of root hairs in soil. Air space

Clay particle Root hair K+ K+ K+ H+ K+ K+ K+ K+ K+
Figure 32.8C Cation exchange.

CONNECTION: Soil conservation is essential to human life
Human practices in agriculture have degraded soils Irrigation can cause build up of salts in soils Plowed lands are subject to erosion by wind and rain, which removes topsoil Chemical fertilizers are costly and may contaminate groundwater Student Misconceptions and Concerns 1. Students often confuse the terms symbiosis and mutualism, falsely thinking that they mean the same thing. You might wish to clarify these terms to emphasize the win/win nature of mutualism. Teaching Tips 1. The U.S. Department of Agriculture’s Natural Resources Conservation Service provides numerous links and information on soil conservation at Copyright © 2009 Pearson Education, Inc.

Most plants depend on bacteria to supply nitrogen
Most of the nitrogen in the biosphere is in the atmosphere as N2 gas Plants can only absorb nitrogen as ammonium or nitrates from the soil; they cannot absorb it from air Teaching Tips 1. With abundant antibacterial products now on the market, students may believe that all bacteria are harmful. Before addressing the mutualistic roles of soil bacteria and plants, challenge your students to explain why planting seeds in sterilized soil could be problematic. 2. Mycorrhizae provide an excellent example of a mutualistic relationship. Unless the various types of symbiotic relationships have already been discussed, consider illustrating mutualism and parasitism with the relationships in Modules 32.12–32.14. Copyright © 2009 Pearson Education, Inc.

Nitrogen fixation—N2 is converted to ammonia
Atmosphere Soil bacteria can convert N2 gas from the air into forms usable by plants via several processes Nitrogen fixation—N2 is converted to ammonia Amonification—conversion of organic matter into ammonium Nitrification—conversion of ammonium to nitrates, the form most often taken up by plants N2 Soil Amino acids, etc. N2 Nitrogen-fixing bacteria NH4+ Figure The roles of bacteria in supplying nitrogen to plants. H+ NH3 NH4+ (ammonium) NO3– (nitrate) Nitrifying bacteria Ammonifying bacteria Organic material Root

EVOLUTION CONNECTION: Mutually beneficial relationships have evolved between plants and their symbionts Most plants form symbioses with fungi called mycorrhizae Mycorrhizae act like extensions of plant roots, increasing the area for absorption of water and minerals from soil Mycorrhizae produce enzymes that release phosphorus from soil, making it available to plant hosts Mycorrhizae release growth factors and antibiotics into the soil Mycorrhizal symbioses have evolved with plants and were important to plants successfully invading land Student Misconceptions and Concerns 1. Students often confuse the terms symbiosis and mutualism, falsely thinking that they mean the same thing. You might wish to clarify these terms to emphasize the win/win nature of mutualism. Teaching Tips 1. Mycorrhizae provide an excellent example of a mutualistic relationship. Unless the various types of symbiotic relationships have already been discussed, consider illustrating mutualism and parasitism with the relationships in Modules 32.12–32.14. 2. For additional details on mycorrhizal relationships, see the literature exchange website for mycorrhiza at Copyright © 2009 Pearson Education, Inc.

Figure 32.13A A mycorrhiza on a eucalyptus root.

EVOLUTION CONNECTION: Mutually beneficial relationships have evolved between plants and their symbionts Some plants form symbioses with nitrogen-fixing bacteria Legumes (peas, beans, alfalfa, and others) form root nodules to house nitrogen-fixing symbionts in the genus Rhizobium Other plants, such as alders, form symbioses with other kinds of nitrogen-fixing bacteria Plants that form these associations are rich in nitrogen Both mycorrhizae and nitrogen-fixing bacteria benefit by receiving sugars from the plants they colonize Student Misconceptions and Concerns 1. Students often confuse the terms symbiosis and mutualism, falsely thinking that they mean the same thing. You might wish to clarify these terms to emphasize the win/win nature of mutualism. Teaching Tips 1. Mycorrhizae provide an excellent example of a mutualistic relationship. Unless the various types of symbiotic relationships have already been discussed, consider illustrating mutualism and parasitism with the relationships in Modules 32.12–32.14. 2. For additional details on mycorrhizal relationships, see the literature exchange website for mycorrhiza at Copyright © 2009 Pearson Education, Inc.

Shoot Nodules Figure 32.13B Root nodules on a pea plant. Roots

Bacteria within vesicle
Figure 32.13C Bacteria within a root nodule cell.

The plant kingdom includes epiphytes, parasites, and carnivores
Epiphytes Grow anchored on other plants Absorb water and minerals from rain Parasites Roots tap into the host plant’s vascular system Incapable of photosynthesis Absorb organic molecules from host plant Carnivores Trap and digest small animals such as insects Absorb inorganic elements from prey Found in nutrient poor environments Student Misconceptions and Concerns 1. Students often confuse the terms symbiosis and mutualism, falsely thinking that they mean the same thing. You might wish to clarify these terms to emphasize the win/win nature of mutualism. Teaching Tips 1. Mycorrhizae provide an excellent example of a mutualistic relationship. Unless the various types of symbiotic relationships have already been discussed, consider illustrating mutualism and parasitism with the relationships in Modules 32.12–32.14. 2. The International Carnivorous Plant Society maintains a website at The site contains many beautiful photographs of carnivorous plants, answers to FAQs, and numerous related resources. Copyright © 2009 Pearson Education, Inc.

Figure 32.14A Orchids, a type of epiphyte, growing on the trunk of a tree.

Figure 32.14C Mistletoe growing on an oak.
Figure 32.14B Dodder growing on a pickleweed.

Figure 32.14E A Venus’ flytrap digesting a fly.
Figure 32.14D A sundew plant trapping a damselfly.

Transport in plants water and minerals sugar (a) (b) (c) (d) pressure
involves movement of water and minerals sugar from through from through (a) (b) (c) (d) to driven by to driven by pressure flow leaves (e) (f)

You should now be able to
Describe phytoremediation and its uses Explain how water and minerals are taken up by plant roots Describe the transpiration-cohesion-tension mechanism for movement of water through plants Describe how guard cells regulate transpiration Explain how sugars are transported through plants from sources to sinks Copyright © 2009 Pearson Education, Inc.

Give examples of essential elements and tell why they are important Explain how soil characteristics and fertility influence plant growth Explain why soil bacteria are important to all plants and plant nutrition Copyright © 2009 Pearson Education, Inc.

Describe the symbiotic relationships that have evolved between plants and microorganisms and how those relationships improve plant nutrition Differentiate between epiphytes, parasites, and carnivorous plants; describe what each of these kinds of plants gets from its “host” or “prey” Copyright © 2009 Pearson Education, Inc.

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