Unit 2: Plants: Anatomy, Growth and Function

1. Unit 2: Plants: Anatomy, Growth and Function 12.1 The Characteristics of Plants SBI 3U

2. Introduction: Discussion Questions • In what ways do you think leaves are important to plant, humans and ecosystems? • Explain how plants roots are important to the plant and our economy. • Other than for wood, how do humans use stems?

3. Basic needs of plants • Energy, nutrients, water, gas exchange, protection from herbivore and disease and reproduce http://www.iknow2.net/what-do-plants-need-to-survive/

4. Energy • Plants use photosynthesis to produce glucose, energy source for plant • Plants have adaptations to ensure light meets are met • Plants have adaptations for protection from predators http://www.celsias.com/article/carbon-friendly-agriculture/

5. Nutrients and Water • Plants need nitrogen, phosphorous, potassium to make compounds for their cells • Obtain them as dissolved in water or by mycorrhizal fungi in their roots http://www.chrismaser.com/truffle.htm

6. Gas exchange • Plants need to exchange gases for photosynthesis and respiration • In vascular plants, gas exchange takes place in leaves http://howplantswork.wordpress.com/page/5/

7. Reproduction • Plants use both sexual and asexual reproduction http://howplantswork.wordpress.com/page/5/

8. Vascular Plant Body: Roots and Shoots • Two main systems: root and shoot • All cell walls contain cellulose • 3 main organs: leaf, stem and root • Also have meristematic tissue from which all other tissues arise http://www.uic.edu/classes/bios/bios100/labs/plantanatomy.htm

9. Plant Tissues • the cells of complex plants are organized into tissues and tissue systems (and organs and organ systems) • plant tissues are specialized to perform functions such as absorption, transport, storage and photosynthesis • See Table 1 on p. 543

10. Plant Tissues • There are 3 major types of specialized plant tissue systems: • dermal tissue system • ground tissue system • vascular tissue system

11. Dermal Tissue System • outermost layer of cells, epidermis and periderm, sometimes protected by waxy cuticle • often have thicker cell walls • protect against injury, herbivores, disease and water loss http://www.agen.ufl.edu/~chyn/age2062/lect/lect_15/22_2BT.GIF

12. Ground Tissue System • storage of carbohydrates (parenchyma) • supports growth and development(parenchyma and collenchyma) • support and protect plant body(collenchyma and sclerenchyma)

13. Vascular Tissue System • xylem tissue transports water and dissolved substances • phloem tissue transports sugars and other solutes

14. Updating Vascular Plant Phylogeny • 3 major groups of vascular plants: lycophytes and pteridophytes, gymnosperms and angiosperms • Scientists have further classified dicots into 4 groups

15. Unit 2: Plants: Anatomy, Growth and Function 13.5 Plant Growth and Development SBI 3U

16. Types of growth • Primarygrowth includes: • growth in length of roots and stems throughout a plant’s life • growth in diameter of roots and stems during the first year of a plant’s life • Secondarygrowth includes: • growth in diameter of roots and stems during the rest of a plant’s life

17. Primary growth • Shoot apical meristem will form stems, leaves and organs for sexual reproduction • Root apical meristem will form cells of root cap and all root cells • Zone of maturation is where cells finish differentiating, zone of elongation is where cells lengthen and zone of cell division is where cells divide http://www.uic.edu/classes/bios/bios100/labs/plantanatomy.htm

18. Secondary growth • Only in woody species after first year • Happens via two lateral meristems: cork cambium and vascular cambium • Cork cambium produces cells that form a bark • Vascular cambium produces new secondary xylem and phloem each year. • Growth rings are larger in wetter seasons http://jewelrytbfy.com/q/annual+rings/

19. Environmental factors • Light • Water • Temperature • Nutrient

20. Light • certain wavelengths of visible light are more desirable for plant growth • plants detect changes in light conditions through molecules called photoreceptors • photoperiodism is a plant’s reponse to changes in day length. http://www.botanik.uni-koeln.de/hoecker_research.html

21. Nutrients • two categories of plant nutrients: macronutrients and micronutrients • Macronutrients are needed in large quantities • Micronutrients are only needed in small amounts. The 8 micronutrients are boron, chlorine, copper, iron, manganese, molybdenum, nickel and zinc http://www.bionaturefertilizer.com/BIO%20NATURE%20explanation.htm

22. Temperature • there is specific temperature range at which plants work best. Ex. The opening and closing of stomata is affected by temperature • temperature also acts as signal for plants to begin a developmental stage such as flowering or seed germination http://tomclothier.hort.net/page11.html

23. Soil • soil provides medium in which roots anchor themselves • soil needs to have sufficient humus • pH of soil is also important to ensure appropriate growth and development (most plants prefer mildly acidic soil) http://www.omafra.gov.on.ca/english/environment/soil/chemical.htm