DAY 5 OF CHAPTER 25 NOTES http://www.toto.com/misha/mavica/folliage2.jpg Asexual reproduction in plants is also known as vegetative reproduction. Methods of vegetative reproduction include plant structures such as: 1)Runners: Horizontal above ground stem (airplane plant). 2)Bulbs: (monocots) Short stem with fleshy leaves (tulip). Corms: Short, thickened underground stem with scaley leaves (crocus) Rhizomes: Horizontal underground stem (fern). Tubers: Large, fleshy underground stem (potato). Big Advantage!:Vegetative reproduction is a faster way to reproduce compared to sexual reproduction if the environment is favorable. 1
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Plant Propagation: growing new plants from seed or from vegetative parts. Types of Vegetative Reproduction Budding and Grafting: attach small stems from one plant attached to larger stems or roots from another plant. Taking Cuttings: Leaves or pieces of stems are taken from one plant to grow new individuals. Tissue Culture: Tissue from a plant is placed on medium and used to grow a new individual. Objective: Draw the cross-section of a woody and non-woody stem and locate various plant tissues. http://www.flickr.com/photos/roddh/377834258/ 3
Cortex: the ground tissue outside the vascular bundles. Pith: the ground tissue inside the ring of vascular bundles. Woody Plants = plants that have stiff nongreen woody stems. Young Woody Stem Cork: outer covering of a woody plant Pith: central core of the stem Ring of Xylem: surrounds the pith Ring of Phloem: Surrounds the ring of xylem Ring of Cork: Surrounds the ring of xylem Bark = Cork + Phloem 4
Mature Woody Stem Heartwood: wood in the center of a mature tree. Xylem in the heartwood can not transport water. They just add support. Sapwood: located outside the heartwood. Xylem here can transport water. http://www.infovisual.info/01/img_en/007%20cross%20section%20of%20a%20tree%20trunk%20and%20stump.jpg Objective: Map out the method by which seeds germinate,. List what nutrients are necessary for plant growth. Describe the affect of hormones on plant phototropism. 5
Germination: plant embryo growth DICOT MONOCOT #4 Sheath #3 Young Shoot #1 Hook #2 Young Shoot Plant are often identified by their life spans. #1 Perennials: lives several years Examples: Trees, lilies, many vines #2 Annuals: Completes its lifecycle in one season and then dies. Example: Beans, corn, and many weeds #3 Biennials: Two growing seasons are needed to complete its life cycle. First growing season nutrients go to roots and stems. Second growing season stored nutrients used to make a flower. Examples: Carrots and Parsley REMEMBER: IT TAKES A LOT OF ENERGY TO MAKE A FLOWER! Plant Growth Continued Primary Growth: growth that increases the height or length of a plant. Apical meristem: tips of stems and roots that undergo mitosis (cell division) = growth Secondary Growth: growth that increases the width of the stems and roots. 6
http://www.steve.gb.com/images/science/apical_meristem.png http://virtual.yosemite.cc.ca.us/randerson/lynn's%20bioslides/43.jpg Nutrients for Plant Growth The Big 3 Nitrogen: part of proteins promotes growth of green parts Phosphorus: part of energy molecules and DNA promotes general growth Potassium: Needed for cells (especially cell membranes) to function properly. Other important nutrients include: Calcium: for cell walls Magnesium: part of chlorophyll needed for photosynthesis. Sulfur 7
Plant Growth Hormones What is a hormone? Answer: chemical produced in one part of an organism where it is transported elsewhere to cause a response. Example: Auxin (pretty cool): #1 Accumulates on the dark side of the plant. #2 Causes cell walls on the dark side to become more flexible and elongate. #3 This causes the plant to bend and grow towards a light source. This bending towards a light source is called phototropism. http://www.chadevans.co.uk/gcsebiology/biologylesson/gb3/gb3l12notes_files/image001.png http://cccmkc.edu.hk/~sbj-biology/al%20bio/continuity%20of%20life%20growth%20and%20develo pment/growth%20and%20development_image/tropism_image/phototropism%20in%20mung%20be 8