Plants Our Most Important Resource The food that

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Plants – Our Most Important Resource

Plants – Our Most Important Resource

 • The food that you eat, oxygen that you breathe and fabric that

• The food that you eat, oxygen that you breathe and fabric that you wear all come from plants. • It is sometimes difficult to imagine all the materials that we rely on daily originate from plants. In fact, plants changed the way of life some 10, 000 years ago. • Civilization changed from a nomadic lifestyle to domestication when people began to grow plants and raise livestock. • Farming food staples like corn, wheat, rice and potatoes and rearing goats, chickens and cows allowed for the development of settlements and communities.

 • In this section, we will learn about many different uses of plants

• In this section, we will learn about many different uses of plants and the communities that depend on plants.

Medicine • Prior to local drugstores being opened on every other street corner, people

Medicine • Prior to local drugstores being opened on every other street corner, people relied on the healing powers of plants. • Plants produce over 10 000 different compounds to protect themselves against predators. • Chemists are able to extract and use these chemicals to cure and treat common illnesses and diseases. • The following table summarizes a few examples:

Plant Active Compound Uses in Medicine Ephedra Ephedrine Decongestant, treat low blood pressure and

Plant Active Compound Uses in Medicine Ephedra Ephedrine Decongestant, treat low blood pressure and asthma Cinchona Salix Quinine Salicin Treatment of malaria Anti-Inflammatory Digitalis purpurea Digitoxin, digoxin Cardiac stimulant, diuretic Papaver Morphine, codeine somniferum Rauwolfia Reserpine serpentina Nicotiana tabacum Nicotine Dioscorea Catharanthus roseus Cough suppressant High blood pressure and psychosis Stimulant Steroids Production of cortisone Vinblastine Leukemia, Hodgkin's disease and other cancers

 • Poppy seeds contain opium which has been used since 4 000 B.

• Poppy seeds contain opium which has been used since 4 000 B. C. • In the 1800 s, opium was a common ingredient in cough syrup. • Opium has a dark side as well. It contains morphine which can then be made into heroin. • • Heroin is an extremely additive illegal drug that once metabolized is converted back to morphine. Heroin affects multiple organ systems including respiratory, nervous and reproductive.

Lumber • In the story of the three little pigs, you may recall that

Lumber • In the story of the three little pigs, you may recall that the pig that built his house out of bricks was able to withstand the force of the hungry wolf's gusts of air. • However, you probably were not informed that in order to build a brick home, a frame made out of wood would be necessary. • Canada exports seven billion dollars worth of lumber to the United States each year and over 200 000 Canadians are employed within this industry.

 • The spin-off construction, transport, and manufacturing jobs that result from the lumber

• The spin-off construction, transport, and manufacturing jobs that result from the lumber industry are significant to the Canadian economy. • Softwood lumber includes wood that is easy to saw and comes from coniferous trees like pine, cedar and • These hardwoods can be used in construction, spruce. furniture, and flooring as • Hardwood lumber includes they are harder and denser beech, cherry and oak. than softwood.

Food • The most important use of plants is food. Up to 90% of

Food • The most important use of plants is food. Up to 90% of our caloric intake comes from wheat, corn, rice, and potatoes. • Grains provide an excellent source of complex carbohydrates. • Beans, lentils, and peanuts offer a good source of protein. • Leafy green vegetables, like cabbage and lettuce, provide fibre, minerals and vitamins. • Oils from avocadoes, sunflowers and olives nourish us with healthy unsaturated fats.

 • In addition to food, herbs and spices also originate from plants. •

• In addition to food, herbs and spices also originate from plants. • Oregano, cinnamon, chili peppers, and other spices help to flavour and preserve food. • The two most popular drinks in the world, coffee and tea, are made from plants.

 • Through the process of selective breeding, cloning, and genetic engineering, many new

• Through the process of selective breeding, cloning, and genetic engineering, many new plant species have been created. • The diversity of plants is increasing in the creation of hybrid plants that contain desirable qualities. • These newly formed plants may be able to sustain harsh environmental conditions such as droughts or floods and therefore provide a better yield.

Other Products • If you think about all the major holidays, some type of

Other Products • If you think about all the major holidays, some type of plant is involved. • From the Christmas tree to the Halloween pumpkin, plants have an impact on celebrations. • The colour and aroma of flowers fills a church during weddings and funerals. • The cornucopia's presence at Thanksgiving is a symbol of the importance of harvest time.

 • The use of plant crops as an alternative to gasoline is having

• The use of plant crops as an alternative to gasoline is having a global impact. • Ethanol is the fuel that is produced from the combination of gasoline and an organic compound like sugar cane or corn. • The use of a renewable resource as a fuel has many benefits. • The emissions from biofuels do not release as much carbon dioxide and therefore reduce the greenhouse effect.

 • However, biofuels are affecting more than oil companies, with corn and sugar

• However, biofuels are affecting more than oil companies, with corn and sugar being grown for fuels, the world's food prices increased by 75% in 2008 (World Bank, 2008).

 • Plants provide leisure activities to millions of people around the world who

• Plants provide leisure activities to millions of people around the world who enjoy planting, growing, and nurturing their gardens. • Growing seasons are celebrated all over the province of Ontario. • Annual festivals celebrating strawberries, corn, and tomatoes are a reminder of the importance of locally grown crops.

Required Reading • The Boreal Forest – A Global Legacy (on website) • Biofuels

Required Reading • The Boreal Forest – A Global Legacy (on website) • Biofuels – The Promise and the Risks (on website) • Our Life Medicine Path (on website) • Answer the questions (on website) on this article

Plant Structure

Plant Structure

 • One of the distinguishing characteristics that you may recall from the diversity

• One of the distinguishing characteristics that you may recall from the diversity unit is that all plants carry out the process of photosynthesis. • This process is essential not only for the survival of a plant, but for the survival of all living things. • The organelle whose duty it is to carry out this daunting task is the chloroplast. • The image on the next slide highlights all the components of a plant cell. • You should be able to describe the function of all the organelles shown below. If not, then please take the time to review.

Roots • There are many analogies equating roots with positive attributes like strength, stability,

Roots • There are many analogies equating roots with positive attributes like strength, stability, and support. • A person who has strong roots implies that he or she has a solid foundation that is built upon firm principles. • It is no surprise then to learn that those qualities that are assigned to people are the same qualities that roots provide to plants. • In addition to anchoring plants in soil, roots also absorb and transport water and minerals to the stems.

 • Not all roots are the same. • Tap roots grow deep into

• Not all roots are the same. • Tap roots grow deep into the ground in search of nutrients. They are generally large and fleshy and store food which is necessary for perennial plants (plants that last more than two growing seasons) which experience periods of dormancy. • Fibrous roots do not dig deep into the soil; rather they arrange themselves close to the soil surface and collect water and nutrients before they sink deep into the ground. • Adventitious roots are found in climbing plants like ivy. These roots develop from other plant tissue like stems and leaves. Adventitious roots can help support a plant.

 • Roots contain tiny little projections called root hairs. • The root hairs

• Roots contain tiny little projections called root hairs. • The root hairs absorb water and nutrients from the soil. • Much like alveoli that increase surface area for gas exchange, the root hairs amplify the surface area which increases the rate of absorption.

Stems • Stems provide the structural and physical support to leaves and flowers. •

Stems • Stems provide the structural and physical support to leaves and flowers. • The stems hold the leaves and flowers in a position that will allow for nutrient gathering and reproduction. • Xylem and phloem cells transport materials within the stem from areas of plenty to areas of need. • The xylem and phloem cells are arranged in vascular bundles. • Within these bundles, the phloem cells are always situated closer to the outside of the stem while the xylem cells are located closer to the centre of the stem.

 • There is a thin layer of tissue that separates the xylem from

• There is a thin layer of tissue that separates the xylem from the phloem in dicot plants. • Stems also store nutrients for future use. • Rhizomes, tubers, and bulbs are all types of stems that have been modified to suit the needs of a plant.

 • Tubers grow underground and develop buds called eyes. These buds grow into

• Tubers grow underground and develop buds called eyes. These buds grow into new shoots above the ground. • Bulbs are small stems that grow underground. They usually have short and thick leaves. • Rhizomes grow just below the surface of the ground are thick and fleshy. They can survive through the winter and develop buds in the spring.

 • There are two main types of stems. • Herbaceous stems are soft

• There are two main types of stems. • Herbaceous stems are soft and green and woody stems are more complex and are hard. • Most trees and plants that can survive through winter have woody stems. Woody stems grow thicker over time. • Each year a new layer forms and the stem of the tree widens. • This is the result of new xylem being formed each spring. The older xylem no longer transports fluids and fills with oils and other chemicals to become heartwood.

 • The vascular cambium appears as rings when looking at the cross section

• The vascular cambium appears as rings when looking at the cross section of a woody stem. • The rings can be counted to determine the age of the tree. The outer part of a woody stem is called the bark. The bark is composed of phloem cells and cork tissue. These cells and tissues protect the stem from water loss.

Leaves • The primary site of photosynthesis occurs at the leaves. • Leaves are

Leaves • The primary site of photosynthesis occurs at the leaves. • Leaves are positioned on trees to receive and absorb the sun's rays. • This is necessary to drive the process of photosynthesis. • Leaves have many variations in their shape, size and structure. • A compound leaf contains a leaf that is divided into many smaller leaflets. • A simple leaf has just one blade.

Compound Leaves Simple Leaves

Compound Leaves Simple Leaves

 • A leaf is made up of many specialized cells and tissues as

• A leaf is made up of many specialized cells and tissues as illustrated in the image below:

 • 1. Cuticle - The cuticle is a waxy, water resistant covering that

• 1. Cuticle - The cuticle is a waxy, water resistant covering that protects the leaf from excessive absorption of light and evaporation of water. • 2. Upper Epidermis - These cells appear on the top of the leaf and are transparent and colourless. They allow light to pass through to mesophyll cell where most of photosynthesis takes place. The epidermis lack chloroplasts therefore no photosynthesis takes place. • 3. Palisade Mesophyll - These cells are arranged close together and contain chloroplasts. These photosynthetic cells form the bulk of plant leaf. • 4. Spongy Mesophyll - These cells also contain chloroplast, but not as many as the palisade cells. The spongy mesophyll cells are not as densely packed together. This allows more surface area for gas exchange.

 • 5. Lower Epidermis - These cells appear on the bottom of the

• 5. Lower Epidermis - These cells appear on the bottom of the leaf and are transparent and colourless. They allow light to pass through to mesophyll cell where most of photosynthesis takes place. The epidermis lack chloroplasts therefore no photosynthesis takes place. • 6. Stoma - Stomata (pl. ) are small openings located on the underside of the leaf of most plants. These small openings allow for oxygen, carbon dioxide, and water vapour to move into and out of the leaf. • 7. Guard Cells - Guard cells are specialized epidermal cells that contain chloroplasts. Guard cells regulate the opening and closing of the stoma. When weather conditions are hot and dry, the guard cells collapse and the stoma closes.

 • The process that regulates the opening and closing of the stoma involves

• The process that regulates the opening and closing of the stoma involves the movement of ions and water. • This animation shows how the shape of the guard cells affects the condition of the stoma. • Well it would if it worked! Grrrrrr.

 • 8. Xylem - Xylem are specialized structures that transport water and minerals

• 8. Xylem - Xylem are specialized structures that transport water and minerals from the roots to the rest of the plant. • 9. Phloem - Phloem cells are specialized structures that • transport carbohydrates produced in the leaves to all parts of the plant. 10. Vascular Bundle - The veins of the leaf contain both xylem and phloem cells.

Homework • Roots contain specialized cells and tissues. • Determine the role of the:

Homework • Roots contain specialized cells and tissues. • Determine the role of the: Epidermis, Cortex, Endodermis and Vascular Cylinder. • If you use the Internet, be sure to use academic sites.

Classifying Plants • You briefly explored the different types of plants in the diversity

Classifying Plants • You briefly explored the different types of plants in the diversity unit. • In this unit, you will take a closer look at the differences that exist between the species of plants.

Vascular Tissue • The transportation of materials within multicellular organisms is vital for survival.

Vascular Tissue • The transportation of materials within multicellular organisms is vital for survival. • Plants require water, minerals, sugars, etc. , to circulate throughout its tissues and cells. • Some plants lack specialized structures to carry out this transportation and simply rely on the process of diffusion. • Other plants contain specialized structures that move materials throughout the plant.

 • Non vascular plants lack these specialized structures. • They have poorly developed

• Non vascular plants lack these specialized structures. • They have poorly developed roots, stems and leaves. • They must exist in moist environments for reproduction and transportation to occur. • These plants cannot grow very tall and do not provide much nourishment for humans. • Non vascular plants include mosses, liverworts and hornworts.

 • Vascular plants contain specialized structures called xylem and phloem. • These tissues

• Vascular plants contain specialized structures called xylem and phloem. • These tissues move materials throughout the plant. • The phloem is composed • The xylem is composed of living tissue and it of dead cells and it transports sugars from the transports water and leaves to the other areas mineral from the of the plant. ground upwards.

 • Vascular plants can be divided into two categories: • gymnosperms and angiosperms.

• Vascular plants can be divided into two categories: • gymnosperms and angiosperms.

 • Gymnosperms are plants that produce cones instead of flowers. • They include

• Gymnosperms are plants that produce cones instead of flowers. • They include pine, furs, spruce, ginkgoes and cycads. • These types of plants • thrive in environments that have long cold winters and low nutrients in the soil. Gymnosperms are important for the Canadian economy as the wood from these trees is used to for construction, fuel and pulp and paper.

 • Angiosperms are more diverse than gymnosperms and include flowering plants. • All

• Angiosperms are more diverse than gymnosperms and include flowering plants. • All angiosperms produce food, although not all the food is edible. • Included in this group are grasses, wheat, rice, • Angiosperms provide corn, fruits, vegetables nourishment, fibre for and wildflowers. clothing and medicinal ingredients. • In addition, the wood from these plants can also be used as building materials.

Angiosperms are divided into monocots and dicots.

Angiosperms are divided into monocots and dicots.

Monocots and Dicots • Angiosperms are divided into two subclasses monocotyledon (monocots) and dicotyledon

Monocots and Dicots • Angiosperms are divided into two subclasses monocotyledon (monocots) and dicotyledon (dicots). • Most angiosperms are monocots and include grasses, wheat, rice and bananas. • Dicots include the tomato plant, cacti, maple and oak trees. • The name of each subclass is determined by the structure of its seeds. • A seed is made up of three parts: seed coat, embryo and endosperm.

 • Monocots have only one seed leaf (cotyledon) whereas dicots have two seed

• Monocots have only one seed leaf (cotyledon) whereas dicots have two seed leaves. • Seed leaves provide nourishment. • Monocots get their nourishment from the endosperm. • It is believed that monocots came from an early dicot plant.

Homework • You have learned that angiosperms are divided into monocots and dicots. The

Homework • You have learned that angiosperms are divided into monocots and dicots. The division was made based upon the structure of their seeds. Monocots contain one cotyledon and dicots contain two cotyledons. • However, there are many more differences between monocots and dicots. • Using the following criteria listed below, compare monocot and dicot plants. Your comparison should be completed using an organized data table. Criteria: Vascular Bundles; Leaf Venation; Roots; Flowers; Pollen; Secondary Growth.

Plant Reproduction

Plant Reproduction

 • Like all other living things, plants also need to reproduce to produce

• Like all other living things, plants also need to reproduce to produce more plants. • Plants can reproduce asexually or sexually. • Botanists and farmers have been able to interfere in the reproductive process of plants to produce new plants with desirable characteristics. • This had an impact on diversity and quality plant food production.

Reproduction in Nonvascular Plants • Nonvascular plants can reproduce asexually through the process of

Reproduction in Nonvascular Plants • Nonvascular plants can reproduce asexually through the process of vegetative reproduction. This occurs when part of the plant breaks off and a new identical plant develops. • Most nonvascular plants reproduce sexually. The male gamete is called an antheridium and it produces a flagellated sperm. The female gamete is called an archegonium and it produces a single egg. • A moist area is needed for reproduction to occur. Water allows the male sperm cells to swim from the antheridium to the archegonium. • The fertilized egg cell divides by mitosis and develops into an embryonic sporophyte within the archegonium.

 • Most plants have a life cycle that includes a diploid generation, sporophyte,

• Most plants have a life cycle that includes a diploid generation, sporophyte, and a haploid generation, gametophyte. • The gametophyte generation is the dominant generation in nonvascular plants. • The sporophyte grows into a long stalk but remains attached to the archegonium. • A sporangium forms at the tip of the long stalk and haploid spores develop through meiosis. • The sporangium bursts and the spores scatter and they germinate by mitosis forming mature gametophytes.

Reproduction in Vascular plants • Gymnosperms produce cones that are either male cones or

Reproduction in Vascular plants • Gymnosperms produce cones that are either male cones or female cones. • Male cones are small and generally found in clusters. • The male cones produce and release haploid pollen cells that resemble yellow dust. • Female cones are also small but are very sticky. • This allows the pollen to adhere to the cone so that fertilization can occur.

 • When the pollen grain attaches to the female cone, it must travel

• When the pollen grain attaches to the female cone, it must travel to the female gametophyte where the archegonium houses the egg cell. • The pollen grain travels to the opening of the ovule called the micropyle and attaches itself to the nucellus. • Here it will grow and develop into a male gametophyte.

 • The male gametophyte releases haploid sperm cells that will eventually fertilize the

• The male gametophyte releases haploid sperm cells that will eventually fertilize the female egg cell to produce a diploid zygote. • The zygote grows and develops into a seed within the female gametophyte. • It is protected by a layer of tissue called the integument that will become the seed coat. • Soon enough the seeds will be released and germination will occur.

Reproduction in Angiosperms Flowering plants usually contain both the female and male parts. The

Reproduction in Angiosperms Flowering plants usually contain both the female and male parts. The female area of the plant is called the carpel and it includes the stigma, style, ovary, and ovules or eggs. The male part of the flower is called the stamen and it includes the filament, anther, and pollen or sporangium.

 • When a pollen grain reaches the stigma, it germinates into a pollen

• When a pollen grain reaches the stigma, it germinates into a pollen tube. • The germ cell divides by mitosis forming two sperm cells. • These sperm cells migrate down the pollen tube as it grows through the style, micropyle, and into the ovule chamber. • The pollen tube enters the ovule through the micropyle and it breaks open.

 • One sperm cell fertilizes an egg cell forming a diploid zygote. •

• One sperm cell fertilizes an egg cell forming a diploid zygote. • The other sperm cell fuses with a polar egg cell (non-functioning) to form the endosperm. • This is called double fertilization. • The endosperm will provide nourishment to the developing seed. • After fertilization, each ovule develops into a seed. • The ovule covers and protects each seed.

Germination • When a seed is released, it may not germinate immediately. Growth may

Germination • When a seed is released, it may not germinate immediately. Growth may be delayed until favourable conditions are present. Most seeds will experience a period of dormancy. This period may be a couple of days or even a couple of years before germination starts. • Germination begins when a hormone called gibberellin is released into the seed from the embryo. This hormone activates enzymes that break down starch into smaller molecules to be used as a source of energy for the embryo.

 • As this occurs, water moves into the seed through osmosis and the

• As this occurs, water moves into the seed through osmosis and the seed coat begins to swell. • Often small cracks will result from the swelling of the seed and this allows oxygen to enter the seed. • With oxygen present, the embryo can undergo aerobic cellular respiration and produce even more energy in the form of ATP.

 • The tip of the radicle emerges out of the seed first and

• The tip of the radicle emerges out of the seed first and elongates downwards forming the roots. • The hypocotyl emerges next and it forms a hook and elongates upwards and becomes the stem. • • The hypocotyl grabs the cotyledon as it moves upwards towards light. Initially the cotyledons act like leaves and carry out photosynthesis, but as the plant develops, true leaves form and the cotyledon fall off.

Artificial Reproduction • The need to produce more food and commercially viable plant products

Artificial Reproduction • The need to produce more food and commercially viable plant products has caused horticulturists and farmers to influence the natural fertilization process of plants. • Here a few modified processes of plant reproduction.

 • Selective breeding has been used by farmers for many years. • In

• Selective breeding has been used by farmers for many years. • In this process of sexual reproduction, farmers choose plants that have desirable qualities and only allow them to fertilize each other. • Over time, the desirable qualities will be present in all the seeds and the unfavourable characteristics will be eliminated. • This procedure is similar to what Gregor Mendel did in order to get his pure bred plants. • Wheat, corn, and bananas are a few examples of plants that have been selectively bred.

 • Cutting is a form of asexual reproduction that is very easy to

• Cutting is a form of asexual reproduction that is very easy to perform. • If there is plant that has desirable traits you can simply cut a piece of the plant that includes the stem and place it in water or soil. • Tissue will start to develop from the cut end of the stem. • This tissue is called a callus and will eventually develop into roots. • This new plant is genetically identical to the parent plant it came from.

 • Grafting is a form of asexual reproduction that can only be done

• Grafting is a form of asexual reproduction that can only be done with plants that have vascular cambium, the tissue between xylem and phloem cells in dicot plants. • A bud (scion) from a plant that has desirable characteristics is grafted or attached to the root or stem (stock) of another plant. • At the site of attachment, the cambium of the scion fuses with the cambium of the stock. • This process allows farmers to grow genetically identical trees. • Apples, grapes, plums, and peaches are all produced by grafting.

 • The Macintosh apple was discovered in Ontario in 1811 by John Macintosh.

• The Macintosh apple was discovered in Ontario in 1811 by John Macintosh. Learn about the history of the Macintosh apple.

Homework • There are many good sites that animate the process of fertilization in

Homework • There are many good sites that animate the process of fertilization in gymnosperms. Life cycle of a Conifer is one that you can try. • There are many good animations that show fertilization occurs in angiosperms. You should view this Double Fertilization Video.

Informal Quiz Time – Is it True or Is It False? 1. Nonvascular plants

Informal Quiz Time – Is it True or Is It False? 1. Nonvascular plants require a moist environment for asexual reproduction. 2. The sporophyte is the dominant generation in the life cycle of nonvascular plants. 3. Male cones are smaller than female cones and are arranged in clusters. 4. In gymnosperms, pollen attaches to the egg cell and fertilization occurs. 5. The female part of an angiosperm includes the stigma, style, and ovary.

Answers 1. False. A moist environment is needed for sexual reproduction. 2. False. The

Answers 1. False. A moist environment is needed for sexual reproduction. 2. False. The gametophyte generation is the dominant generation in the life cycle. 3. True. 4. False. Pollen attaches to the nucellus and grows and develops into a gametophyte. The gametophyte releases sperm cells that fertilize the egg cell. 5. True.

6. Double fertilization occurs in angiosperms. 7. The endosperm provides nourishment to the developing

6. Double fertilization occurs in angiosperms. 7. The endosperm provides nourishment to the developing embryo. 8. A growth hormone called radicle starts the germination process. 9. The radicle eventually develops into the root and the hypocotyl develops into the stem. 10. Grafting is a form of asexual reproduction that combines the buds of one plant with the stem of another.

Answers 6. True. 7. True. 8. False. The hormone that starts the germination process

Answers 6. True. 7. True. 8. False. The hormone that starts the germination process is called gibberellin. 9. True. 10. True.

Plant Growth

Plant Growth

 • Plants require basic nutrients to sustain themselves. • Since plants are autotrophic,

• Plants require basic nutrients to sustain themselves. • Since plants are autotrophic, they need water, carbon dioxide, and sunlight to produce the organic compounds needed for cellular processes like growth and energy. • In addition to manufacturing organic compounds, plants acquire water and minerals from the soil through their roots. • The ability of plants to attain water, nutrients, and sunlight can greatly affect their growth and ultimately their survival.

 • Recall from the last activity that plant growth begins when a seed

• Recall from the last activity that plant growth begins when a seed begins to germinate. • From the tiny seed, a main root and stem start to appear and soon enough an entire plant exists. • Just like multicellular organisms, plants contain specialized structures, tissues and cells that perform specific tasks. • Growth in plants occurs at the meristematic tissue where rapid mitosis produces new cells. This is called primary growth. • Plants can only grow in areas where meristematic tissue occurs and these areas are called meristems.

 • Apical meristems are located at the root tip and at the ends

• Apical meristems are located at the root tip and at the ends of shoots. • Apical meristems located in the root tip produce cells that enable the stem to grow in length. • The apical meristems that are located at the end of shoots give rise to buds and leaves.

 • The vascular cambium which you looked at earlier in this unit causes

• The vascular cambium which you looked at earlier in this unit causes a plant to grow wider. This is called secondary growth. • The vascular cambium is a ring of meristematic tissue that separates the xylem from the phloem in dicots. • Recall that the xylem cells are located in towards the centre and the phloem cells are located near the exterior.

 • There are three requirements for plant growth: 1. Soil Nutrients 2. Sunlight

• There are three requirements for plant growth: 1. Soil Nutrients 2. Sunlight 3. Water

Soil Nutrients • Soil consists of many different components that are required by plants

Soil Nutrients • Soil consists of many different components that are required by plants and it is arranged in several layers. • Using the diagram on the right as a guide, the top layer of soil (O) is called humus and it is composed of dead and decaying plant and animal remains. • The presence of high concentration of humus in the soil will support plant growth.

 • The next layer (A) is topsoil and this is the layer that

• The next layer (A) is topsoil and this is the layer that will support plant growth. • It is made up of humus, clay, minerals and sand. • The next layer (B) is called subsoil. Many worms, insects and microorganisms live in the first three layers. • In addition, the roots absorb water and dissolved minerals • As shown in these layers. The last layer illustration, the growth of (C) is bedrock and it does not the roots stops at the end support plant growth. of the subsoil level.

 • The minerals that are needed by plants in small amounts include iron,

• The minerals that are needed by plants in small amounts include iron, zinc and copper and are referred to as micronutrients. • Macronutrients like nitrogen, phosphorus, potassium, calcium and magnesium are required in larger amounts. • The absence of any of these nutrients may cause a plant to die. • Each nutrient is required by plants to carry out cell functions like cellular respiration or photosynthesis.

 • Sometimes people will help replenish the soil by adding fertilizers that contain

• Sometimes people will help replenish the soil by adding fertilizers that contain specific nutrients. • Commercially produced fertilizers usually contain nitrogen, phosphorus and potassium as percentages. • The percent composition of each nutrient allows people to choose the appropriate fertilizer for the type of plant or the type of growth they want to achieve. • Some people may choose to apply organic fertilizers like manure on their crops or in their gardens. • One of the benefits of organic fertilizers is that they release the nutrients slowly into the soil. • This prevents accidental chemical burns that may occur when too much commercial fertilizer is applied.

Sunlight • Plants use the energy of the sun to drive the process of

Sunlight • Plants use the energy of the sun to drive the process of photosynthesis. • The light from the sun's rays is needed to activate special enzymes within the chlorophyll of the chloroplasts. • There are many factors associated with light and its effect on plant growth and photosynthesis.

 • Light Intensity: The growth of a plant affected by its location. A

• Light Intensity: The growth of a plant affected by its location. A plant may be placed in direct sunlight, partial sunlight or in the shade. Plants that are in the shade grow the least. • Light Quality: Chlorophyll, the green pigment common to all photosynthetic cells, absorbs all wavelengths of visible light except green, which it reflects to be detected by our eyes. • Duration: Plants that are exposed to longer periods of light will grow faster. Shorter periods of light provide less energy to drive the process of photosynthesis. Excessive amounts of light may cause a plant to lose excessive amounts of water through transpiration

Water • Plants require water for growth, temperature regulation, and for support. • Remember

Water • Plants require water for growth, temperature regulation, and for support. • Remember that water is one of the reactants needed for photosynthesis. A plant that does not have sufficient amounts of water will wilt. • Plants that receive too much water actually prevent the roots from taking in oxygen. The root cells require oxygen for cellular respiration and they get the oxygen from tiny pores in the soil. • If the soil is drenched with water, the root hairs are not able to take in oxygen.

Activity • Why Are my Plants turning Yellow?

Activity • Why Are my Plants turning Yellow?

Plant Hormones • You have already learned the effect that the plant hormone gibberellin

Plant Hormones • You have already learned the effect that the plant hormone gibberellin has on germination. • There are two other groups of plant hormones that control the cell division and growth in plants: auxins and cytokinins. • Two additional hormones called abscisic acid and ethylene also alter rate of cell division and growth.

Auxins • You probably have noticed that plants grow and gravitate towards light. •

Auxins • You probably have noticed that plants grow and gravitate towards light. • You can see that effect if you have ever placed a plant near a window or walked through a forest and noticed the shapes of stems and branches of trees. • Auxin is a plant hormone that is released from a plant tip when the cells are exposed to light. • Auxin is released and it travels to the cells of the stem that are not exposed to light.

 • This causes the cells on the dark side to elongate and as

• This causes the cells on the dark side to elongate and as a result, the stem bends towards the light. • In the root, auxin is released from the apical meristems and it causes the roots to grow downwards away from the light. • The cells that are not • If a root cell is exposed to sunlight do not light, auxin will cause elongate. these cells to elongate downward away from the cell.

 • The height of trees is also affected by the presence of auxins.

• The height of trees is also affected by the presence of auxins. • Some trees release auxin from the highest bud which inhibits the growth of buds that appear below. • Plants that have this • Some trees show apical feature usually grow tall dominance through the early and straight. development and then lose • Plants that do not release the feature as they mature. auxin from their terminal • The result is a beautiful shade bud are usually shorter tree that is tall and provides a and bushier. nice reprieve from the sun.

 • In the spring, auxins are present in the leaves of deciduous trees,

• In the spring, auxins are present in the leaves of deciduous trees, but the tree stops producing auxin once the growing season has ended. • Without the presence of • auxin, the leaves can no longer stay attached to the tree and fall off. Auxin is also commercially available and can be applied to promote root growth in cutting, prevent fruits from falling off of trees, inhibit stored potatoes from sprouting, and to produce seedless tomatoes and watermelons.

 • Gibberellins are produced in the apical meristems and work with auxins to

• Gibberellins are produced in the apical meristems and work with auxins to encourage the growth of roots and stems. • By itself, gibberellin stimulates the growth • Commercial gibberellin of leaves, flowering, and promotes the growth of the development of fruits and vegetables, it vascular tissue. delays the ripening of citrus fruits, and it can speed up the flowering of strawberries.

Cytokinins • This hormone is important in the development of specialized plant cells and

Cytokinins • This hormone is important in the development of specialized plant cells and tissue. • As well, it also promotes rapid cell division. • This hormone is produced in the roots of plants and is transported throughout the plant. • Commercially cytokinins are used by florists to keep cut flowers looking fresh. • Cytokinins prevent plant cells from aging.

Other Hormones • Abscisic acid is a hormone that is produced in green leaves,

Other Hormones • Abscisic acid is a hormone that is produced in green leaves, fruits, and root caps. It prevents the germination of seeds, inhibits the growth of buds, and prevents the stomata from taking in carbon dioxide. • Ethylene is gas that is naturally produced by fruits. It stimulates the aging of plant tissue and increases the ripening of fruit. This gas is a problem when fruits are picked and are shipped to other areas. The ethylene gas causes the fruit to ripen quickly.

Homework • http: //home. howstuffworks. com/how-toplant-an-annuals-garden 4. htm • Look through each of the

Homework • http: //home. howstuffworks. com/how-toplant-an-annuals-garden 4. htm • Look through each of the series of animations and complete the exercises: • http: //www. sumanasinc. com/webcontent/ani mations/content/plantgrowth. html • http: //www. kscience. co. uk/animations/auxin. htm

Movement in Plants

Movement in Plants

 • Just like the circulatory system moves materials throughout your body, plants also

• Just like the circulatory system moves materials throughout your body, plants also rely on a system to transport materials. • Remember that xylem and phloem are responsible for moving material within a plant, but without a main pump, how is it that plants can move materials against gravity to heights that surpass the tallest human?

 • Some of the tallest trees in the world are located in south

• Some of the tallest trees in the world are located in south western British Columbia. • The giant Sequoia can grow between 50 - 85 metres high. • That is the about the length of a football field. • Nevertheless, water molecules travel from the roots to the tip of the tree every moment.

Xylem • Xylem vessels are very long, narrow, and hollow tubes that do not

Xylem • Xylem vessels are very long, narrow, and hollow tubes that do not contain any living material. They are connected end to end and stretch all the way from the roots to the leaves. Xylem cells only transport water and minerals that have been absorbed by the root hairs. • Water and dissolved minerals enter the root hairs by osmosis. Recall that osmosis is the movement of water from an area of high concentration to an area of low concentration. The illustration shows the process of osmosis across a cell membrane.

 • For water to enter the root hairs by osmosis there must always

• For water to enter the root hairs by osmosis there must always be a lower concentration of water within the root of the plant. • The only way that this can happen is if the • water is continuously being pulled out of the root or if there is a higher concentration of ions with the root. Each scenario mentioned lowers the concentration of water within the root. The water enters the xylem through pits in the vessels called tracheids.

Root Pressure • Plant roots can build up pressure and the pressure forces the

Root Pressure • Plant roots can build up pressure and the pressure forces the water to move upwards. • The increase in pressure can be caused by active transport of water into the xylem or active transport of ions to create a concentration gradient.

Capillary Action • Capillary action is based on a specific property of water called

Capillary Action • Capillary action is based on a specific property of water called adhesion. • Water has the ability to cling to water molecules (cohesion) or to cling to other molecules (adhesion). • Imagine you have straw and you place it in a glass of water. • The water molecules move up the straw because of the attraction between the water and the straw.

 • However, water molecules are also attracted to each other, so as one

• However, water molecules are also attracted to each other, so as one water molecule moves closer to the straw molecule (adhesion), a second water molecule moves closer to the original • The xylem cells are made up water molecule of tiny thin tubes. (cohesion). • The smaller the diameter of the xylem cells, the higher the water will climb.

Cohesion Tension • As was mentioned with capillary action, water molecules have an affinity

Cohesion Tension • As was mentioned with capillary action, water molecules have an affinity to each other and that is what helps them move up through the xylem. • Remember the specialized structure in the leaf that allows carbon dioxide gas to enter the plant? • The stoma is also the spot where water molecules can escape. • Therefore, as the stoma opens to allow carbon dioxide gas in, water molecules move out. As one molecule leaves, it pulls other water molecules up.

 • Water leaves a plant in a process called transpiration. • Transpiration allows

• Water leaves a plant in a process called transpiration. • Transpiration allows a plant to control its temperature through evaporative cooling. • Excessive water loss through transpiration causes plants to wilt and may also lead to plants dying. • An increase in transpiration increases the movement of water through the xylem.

Transpiration Animation • http: //passel. unl. edu/pages/informationmodu le. php? idinformationmodule=1092853841

Transpiration Animation • http: //passel. unl. edu/pages/informationmodu le. php? idinformationmodule=1092853841

Practice Questions • How do the following weather conditions affect the rate of transpiration?

Practice Questions • How do the following weather conditions affect the rate of transpiration? a) Wind b) Light c) Temperature d) Humidity

Answers a. Wind: Windy conditions increase the rate of transpiration because the wind reduces

Answers a. Wind: Windy conditions increase the rate of transpiration because the wind reduces the effects of a special layer on the leaf that slows the rate of transpiration. b. Light: The stoma open during the day when sunlight is available to drive the process of photosynthesis. Carbon dioxide enters through the stoma for photosynthesis; however, water can also leave through this opening if the temperature is hot. c. Temperature: Warmer air will increase transpiration and cooler air slows down the process of transpiration. d. Humidity: High humidity decreases the amount of water loss through transpiration. Dry air increases the rate of transpiration.

Practice Questions • Explain what is happening in the diagram below.

Practice Questions • Explain what is happening in the diagram below.

Answers • Water has two important properties: cohesion and adhesion. • Cohesion is the

Answers • Water has two important properties: cohesion and adhesion. • Cohesion is the attraction of water molecules to each other and adhesion is the attraction of water molecules to other molecules. This image shows the cohesive property of water. The water droplets stick together and form a droplet on the leaf because of its higher affinity to water droplets than to the surface of the leaf.

Homework • Take another look at the animation on transpiration: • http: //passel. unl.

Homework • Take another look at the animation on transpiration: • http: //passel. unl. edu/pages/informationmodu le. php? idinformationmodule=1092853841 • Click on “transpiration” under where it says lesson media objects. • You could also take a look at the associated readings in the lesson outline on the left!

Phloem • Phloem transport sugars, hormones and other organic molecules throughout the plant. This

Phloem • Phloem transport sugars, hormones and other organic molecules throughout the plant. This process is called translocation. • While xylem transport is generally one direction, the transport of materials within the phloem can go in any direction. • In addition, phloem is composed of living cells. • How materials move within the phloem is yet to be determined. • One of the most supported theories is the Pressure Flow Hypothesis, also called the Mass Flow Hypothesis.

 • In the leaf, glucose is produced by photosynthesis and is converted into

• In the leaf, glucose is produced by photosynthesis and is converted into sucrose for transportation. • The sucrose is actively transported into the cells of the phloem. • This lowers the concentration of water in the phloem. • Water from the xylem moves into the phloem by osmosis and increases the pressure in the phloem area. • As the pressure increases, the sucrose will move to areas of lower pressure.

 • Once the sucrose arrives at the lower pressure areas it is actively

• Once the sucrose arrives at the lower pressure areas it is actively removed from the phloem and into the surrounding cells. • The cells will convert the sucrose back to glucose or another organic compound. • When the sucrose is removed, the pressure drops as water also moves out of the phloem by osmosis.

Tropisms • A Venus fly trap plant is one of the few carnivorous plants

Tropisms • A Venus fly trap plant is one of the few carnivorous plants that exist. • Through highly sensitive hairs, the lobes of the Venus fly trap can rapidly close upon stimulation trapping the unsuspecting insect or spider. • Once trapped inside, any movement by the insect • This type of rapid triggers the lobes to close movement is seen tighter and digestive enzymes in very few plants. are secreted by glands inside the lobes.

 • http: //www. arkive. org/venus-flytrap/dionaeamuscipula/video-00. html • However, all plants show movement in

• http: //www. arkive. org/venus-flytrap/dionaeamuscipula/video-00. html • However, all plants show movement in response to an external stimulus like the sun, gravity or touch. • This type of motion is called tropism. • If a plant moves towards the stimulus, then it is a positive tropism. If the plant moves away from the stimulus, then it is negative tropism. • Some parts of a plant may show positive tropism and other parts of the same plant may show negative tropism.

Phototropism • This tropism is a response to light. • The tips and stems

Phototropism • This tropism is a response to light. • The tips and stems of plants demonstrate positive tropism as they grow towards the light. • The roots of plants grow away from the light and are negatively phototropic. • You will recall that the hormone auxin is released to stimulate growth in stem cells that are not exposed to sunlight.

Geotropism or Gravitropism • This type of tropism is affected by gravity. • Roots

Geotropism or Gravitropism • This type of tropism is affected by gravity. • Roots will display positive tropism and stems and shoots will demonstrate negative tropism. • Charles Darwin was one of the first scientists to identify the growth responses in both roots and stems in relation to gravity.

Thigmotropism • This growth movement is in response to physical contact with another object.

Thigmotropism • This growth movement is in response to physical contact with another object. • Ivy clinging to the surface of walls is an example of positive tropism. • An example of negative tropism includes roots growing away from objects in the soil.

Hydrotropism • Growth of roots towards water is an example of a positive hydrotropism.

Hydrotropism • Growth of roots towards water is an example of a positive hydrotropism. • Roots will gravitate towards a supply of water.

Nastic Response • The movement shown by the Venus fly trap is an excellent

Nastic Response • The movement shown by the Venus fly trap is an excellent example of nastic movement. • The nastic movement of plants is not dependent on the direction of the stimulus. • Rather the movements are random and are not permanent.

Homework • Various tropism videos: • http: //plantsinmotion. bio. indiana. edu/plantm otion/movements/tropisms. html •

Homework • Various tropism videos: • http: //plantsinmotion. bio. indiana. edu/plantm otion/movements/tropisms. html • http: //www. nasa. gov/audience/foreducators/ topnav/materials/listbytype/Tropisms_of_Pla nts. html#. VWt 2 rt. LBxj. M

Succession

Succession

 • How many times have you heard about forest fires destroying acres upon

• How many times have you heard about forest fires destroying acres upon acres of forests in British Columbia or Southern California? • Earthquakes that shake the foundation of landscapes occur randomly throughout the Earth. • It seems that these natural disasters occur more frequently and each one leaves a lasting imprint on the landscape and habitants of the area. • Perhaps there is an acceptable explanation for these natural disasters in preserving the diversity of native plants and organisms?

Review! • Before you proceed through this activity, you will need to familiarize yourself

Review! • Before you proceed through this activity, you will need to familiarize yourself with some terminology. • Define and explain the following terms in your notebook: • ecology, biomes, ecosystem, population, community, habitat, niche, competition, biotic, abiotic.

Definitions • Ecology is the scientific analysis and study of interactions among organisms and

Definitions • Ecology is the scientific analysis and study of interactions among organisms and their environment. • Biomes are large communities of plants and animals that occupy a distinct region. Terrestrial biomes, typically defined by their climate and dominant vegetation, include grassland, tundra, desert, tropical rainforest, and deciduous and coniferous forests.

 • An ecosystem is a community of living organisms in conjunction with the

• An ecosystem is a community of living organisms in conjunction with the non-living components of their environment (things like air, water and mineral soil), interacting as a system. • A population is a summation of all the organisms of the same group or species, which live in a particular geographical area, and have the capability of interbreeding. • A community is a group of a species living in the same place.

 • A habitat is an ecological or environmental area that is inhabited by

• A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant, or other type of organism. • A niche is a position or role within a community. • Competition in biology and sociology, is a contest between organisms, animals, individuals, groups, etc. , for territory, a niche, or a location of resources, for resources and goods, mates, for prestige, recognition, awards, or group or social status, for leadership.

 • Biotic components are the living things that shape an ecosystem. A biotic

• Biotic components are the living things that shape an ecosystem. A biotic factor is any living component that affects another organism, including animals that consume the organism in question, and the living food that the organism consumes. • In biology and ecology, abiotic components or abiotic factors, are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and phenomena associated with them underpin all biology.

 • The landscape of Ontario did not always appear as it does today.

• The landscape of Ontario did not always appear as it does today. • Thousands of years ago, Ontario was covered in ice and not much vegetation was • But as the glaciers retreated new able to exist. rock was exposed and the process of primary succession began.

Primary Succession • Primary succession begins the process of establishing a new ecosystem upon

Primary Succession • Primary succession begins the process of establishing a new ecosystem upon newly formed rocks. • It may begin on lava rock emitted from a volcano or on ground that has been turned upside down by an earthquake or landslide. • Pioneer plants are the first plants to begin growing in the new environment.

 • Lichens represent the first plant-like material to start growing. • Lichens are

• Lichens represent the first plant-like material to start growing. • Lichens are a type of fungus that closely associate with green algae and can grow on rocks, tree bark, and other places with minimal soil. • • The lichens produce acids that slowly corrode the rocks. The rocky materials along with the dead and decaying lichens start to accumulate and soil formation begins.

 • The formation of soil can now support more plant life. • Mosses,

• The formation of soil can now support more plant life. • Mosses, ferns and even seed plants begin to establish themselves in the new area. • Wind carries seeds from • The formation of roots other areas and also helps to break up the germination of the new rocky material. plants can begin.

 • Soil accumulation is the key factor to supporting the growth and development

• Soil accumulation is the key factor to supporting the growth and development of larger native plants. • When larger plants take over the area and vegetation reaches equilibrium, a climax community forms. • Climax communities consist of large trees that take longer to grow and are more shade-tolerant. • Climax communities represent the final stage in primary succession. • Canada has several different climax communities as the environmental conditions will ultimately determine the type of vegetation that will be supported.

 • Virtual Tour of Canadian climax communities:

• Virtual Tour of Canadian climax communities:

Secondary Succession • Secondary succession follows the disturbance of a natural ecosystem either by

Secondary Succession • Secondary succession follows the disturbance of a natural ecosystem either by fire, flood or human activities where the soil remains intact. • That is the difference between primary and secondary succession. • The rate of secondary succession occurs faster due to the presence of soil. • Pioneer organism may also be present in the soil immediately following the disturbance.

 • It is important for you to recognize that secondary succession begins in

• It is important for you to recognize that secondary succession begins in areas that are not completely void of living matter as is the case with primary succession.

 • Ecological succession is best described as a process of change in the

• Ecological succession is best described as a process of change in the species and structure of a community over a period of time. • The population of one species of plant may dwindle over time due to the presence of a natural predator so that eventually the species no longer exists within that community. • Unfortunately, the damage caused by forest fires affects more than one species of plant. • Forest fires erase decades of growth and development, but also bring the promise of new growth.

 • In fact, forest fires are a natural way to maintain the structure

• In fact, forest fires are a natural way to maintain the structure of ecosystems. • A prescribed forest fire is a management tool that is used to maintain and restore the natural ecosystem by eliminating invasive plant and animal species and allowing the native species of plants and animals to return.

Homework • Secondary succession animation: • http: //www. wiley. com/college/strahler/0471 480533/animations/ch 23_animations/animati on 1.

Homework • Secondary succession animation: • http: //www. wiley. com/college/strahler/0471 480533/animations/ch 23_animations/animati on 1. html • Fire management: • http: //www. pc. gc. ca/eng/progs/nppn/eco 5. aspx