Objective 2 and 3 • TEK 4 The student knows that cells are the basic structures of living things and have specialized parts that perform specific functions. (B) Investigate and identify cellular processes including energy production, function of cellular parts, and synthesis of new molecules. • TEK 8 The student knows applications of taxonomy and can identify its limitations. (C ) Identify characteristics of kingdoms. • TEK 13 The student knows the significance of plants in the environment. (A) Evaluate the significance of structural and physiological adaptations of plants to their environments.
Characteristics • Autotrophs • Photosynthesis • Eukaryotic • Multicellular • Requirements: -sun -water -carbon dioxide (CO2)
For 3 billion years life was confined to the sea. • With the development of photosynthesis, oxygen gas began to accumulate. • Some oxygen gas, O2, was converted to ozone, O3, creating a layer of atmosphere. Thus, moving life onto the land. Plant History
Absorbing Minerals • The first plants had no roots and it is thought that they survived by using a symbiotic relationship with fungus to live. • Due to the initial lack of roots, they survived by allowing the fungus to pick up minerals in exchange for some of the plants carbohydrates. • They had to live with large amounts of water to reproduce.
Conserving Water • The first plants had to live near the water to prevent drying out. • In order to occupy drier spaces plants developed a watertight outer covering called a cuticle. Passages called stomata had to be formed to allow for the exchange of gas.
Reproducing on Land • To reproduce sexually plants have always needed water, but for the first time this was not necessary. • Mosses and Ferns had primative eggs surrounded by a jacket of cells and required water for transport. • Formation of seeds, gymnosperms, allowed for freedom on land. The seeds however, never fell far from the tree. • More advanced plants were able to create sperm in the form of pollen grains, angiosperms, and are moved to the female plants by bees and other animals.
Vascular vs. Nonvascular • Vascular plants have tissue to support the transport of water. Ex. Ferns, flowering plants, conifers • Nonvascular plants lack roots, stems, and leaves. Ex. Mosses (bryophyta)
Moss-Bryophyta Flowering Plant-Angiosperm Conifers Gymnosperm Fern
Secondary Stem Growth NOTE: Xylem brings water and minerals up from the roots, while phloem tends to take water to the roots.
Transpiration is the release of water vapor from the leaves of a plant. The water loss generally occurs through the stomata on the leaf surface. 90% of the water entering the leaf is lost by transpiration through the stomata. Only 2% actually is used for photosynthesis and maintaining the cells.
Leaf Functions 1. Leaves are the primary site of photosynthesis in most plants. 2. Mesophyll Cells in Leaves use Light Energy, Carbon dioxide, and Water to make Carbohydrates. 3. Light Energy is also used by Mesophyll Cells to synthesize amino acids, fats, and a variety of other organic molecules. 4. Carbohydrates made in a leaf can be used by the leaf as an Energy source or as building blocks. They also may be transported to other parts of the plant, where they are either used or stored. 5. A major limitation to plant photosynthesis is insufficient Water due to transpiration. About 98 percent of the water that is absorbed by the roots is lost through transpiration. Transpiration may benefit the plant by cooling it and speeding the transport of mineral nutrients through the Xylem.
1. Leaves absorb light, which provides the energy for photosynthesis. 2. Leaves often adapt to their environment to maximize light interception. 3. On the same tree, leaves that develop in full sun are thicker, have a smaller area per leaf, and have more chloroplast per unit area. 4. In dry environments, plants often receive more light than they need. These plants often have structures that reduce the amount of light absorbed. Modifications for Capturing Light 5. Many desert plants have evolved dense coatings of hairs that reduce light absorption. 6. The window plant protects itself from its dry environment by growing underground. Only its transparent leaf tips protrude above the soil to gather light for photosynthesis.
PHOTOSYNTHESIS 6H2O + 6CO2 ----------> C6H12O6+ 6O2
Structures Photosynthesis occurs in leaves. Cells in leaves have chloroplasts. Chloroplasts contain grana, which are filled with thylakoid stacks. Grana are surrounded by a fluid called stroma. The thylakoids contain the pigments, chlorophyll a and b and cartotenoids.
Pigments Chlorophyll is a green pigment common to most photosynthetic cells. In the winter, other pigments are more predominant, giving a variety of colors. In the winter, plants still have chlorophyll, but in lesser amounts. Without chlorophyll, photosynthesis cannot take place. Chlorophyll absorbs all wavelengths of visible light except green, which it reflects to be detected by our eyes.
PHOTOSYSTEMS Pigments actually make up two photosystems, Photosystem I and Photosystem II. Photosystem II comes before Photosystem I because Photosystem I was discovered first. Scientists realized that they were missing part of the process and later found another Photosystem. Photosystem I absorbs light with a wavelength of 700nm. Photosystem II absorbs light with a shorter wavelength of 680nm.
The Process • Water is split, the oxygen goes to us, the hydrogen sticks around to be used later, and the electron is then elevated by the sun. • ADP is converted to ATP by a protein on the electron transport chain. (The electron transport chain are a series of proteins and pigments embedded in the membrane of the thylakoid.) • ATP is then used to split the CO2. The oxygen goes to us and the carbon is used to make sugars. • The excess electrons from Photosystem II are passed on to Photosystem I for use. • The sun then elevates the electrons at Photosystem I. • NADP+ accepts hydrogen, which came from the water being split earlier, to form NADPH. • The hydrogen is used with the earlier carbons to make sugars.
Test Your Knowledge • What three things does a plant need to survive? Gives oxygen to us and hydrogen for sugars Water Sun CO2 Boosts electrons Gives oxygen to us and carbon for sugars. What role do each of these serve?
What are the products of photosynthesis? Sugar and oxygen • What two molecules give us oxygen in the process of photosynthesis? H2O and CO2 • Where does the carbon and hydrogen atoms come from in photosynthesis? Hydrogen atoms from NADPH, which got the hydrogen from the water. Carbon atoms from the CO2, which was broken by ATP.
Bibliography http://www.sirinet.net/~jgjohnso/plants.html http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPLANTANATII.html http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPLANTANAT.html http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html http://ghs.gresham.k12.or.us/science/ps/sci/ibbio/plants/notes/transpir.htm http://homepage.smc.edu/hodson_kent/Cells/Energetics/chloroplastB3.htm http://genbiol.cbs.umn.edu/Multimedia/samples/Photo.gif