Biology II Exam 2 Set Two
Biology II Exam 2 Set Two Bio 1144
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This 4 page Class Notes was uploaded by Murry on Thursday February 4, 2016. The Class Notes belongs to Bio 1144 at Mississippi State University taught by Thomas Holder in Spring 2015. Since its upload, it has received 56 views. For similar materials see Biology II in Biology at Mississippi State University.
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Date Created: 02/04/16
Exam 2 Notes: Set Two • Shoots: leaves and stem o Leaves function through process of photosynthesis o Stems support leaves and transport material from root to leaves o Primary Growth: Elongation o At the shoot tip § Bud- a new shoot; inside is the SAM (Shoot Apical Meristem) • Figure 35.8 in textbook • Inside the bud is a new shoot o Development of shoot different from development of shoot; based on structure of stem o Node – any point along the stem where a leaf, bud, or branch arises o Internode – the region between two nodes; all elongation occurs here o Anatomy of the Leaf § Figure 35.8 in textbook § Upper and Lower Epidermis § Mosophyll – photosynthetic tissue where chloroplasts are located (green tissue) § Vein – a vascular bundle § Stomata - provides gas exchange; oxygen and water vapor leave, carbon dioxide enters § Primary tissue only § Dicot Leaf • Net venation – a network of veins throughout the leaf § Monocot Leaf • Parallel venation – veins run parallel without touching • Leaves always long and slender o Anatomy of the Stem § Mainly above ground structures, but some can be underground § Primary Growth: Elongation § Monocot Stem • Primary growth (elongation) • Scattered vascular bundles; no pattern § Dicot Stem • Primary growth (elongation) • Most have secondary growth (expansion) • Xylem always towards the inside while phloem always towards the outside • Ringed vascular bundles (pith and cortex) • Vascular Cambium – lateral meristem o On the inside, produces secondary xylem (aka: wood) o On the outside, produces secondary phloem (aka: inner bark) • Cork Cambium – lateral meristem; develops late in 1 yearst o On both the inside and outside, produces Periderm – "outer bark” that replaces epidermis and cortex; provides protection • Both Vascular Cambium and Cork Cambium retain cell division properties to produce rings of 20 tissues inside and outside of the cambium ring. This leads to growth in diameter (expansion). • VC happens immediately. • CC happens later in the year. § Secondary Growth of a Dicot Stem after 3 years of Secondary Growth • Growth begins late in the first year • Pith is in the center • Produces cells in rings, although not year round – spring is optimum growing time; stops in the winter à each ring means 1 year of growth • Wood = supportive • Bark = protective and supportive • Figure 35.22 in textbook • Comparison Between Plant Organs (A Summary of Previous Information) o Leaves § primary growth only § Monocot: parallel venation § Dicot: net venation o Roots § Have endodermis and pericyle § Monocot: primary growth only • Has a pith and a cortex § Dicot: primary and secondary growth • Has only cortex (xylem at core) o Stem § Monocot: primary growth only • Scattered vascular bundles • No pith, no cortex § Dicot: primary and secondary growth • Vascular bundles in ring formation • Has both pith and cortex • Growth Review o Primary Growth is Elongation. Roots, stems, and leaves all exhibit primary growth. o Secondary Growth is Expansion. It occurs in stems and roots only. Secondary xylem and phloem are produces due to VC and CC. o Summed up on pg. 735 table 35.2 • Regulation of Plant Growth o Hormones – chemical messengers produces by the plant; mostly internal; transported in phloem tissue o Hormones are produced internally but interact with external environmental factors like temperature, moisture, pH, etc. o Hormones control growth, seed germination, flowering, fruiting, shedding leaves, and color loss. o Growth Inhibiting Hormones – mostly in fall/winter o Growth Promoting Hormones– mostly in spring/summer o Hormones are antagonistic of each other; while one works to promote something, there is always another trying to inhibit the same thing. o All hormones require ATP energy for them to be transported through the plant. o 5 Hormone Types: 1. Auxins • 1 group of hormones that scientists isolated • Produced in shoot tips, leaves, fruits, and seeds (never isolated in roots) • Growth promoting hormones • Requires ATP to move through phloem • Effects: o Promotes cell elongation o Promotes stem elongation o Promotes stem expansion o Promotes development of fruit o Inhibits bud development (auxins promote growth for only 1 season) o Inhibits the abscission (falling off) of leaves, flowers, and fruits 2. Cytokininst • 1 isolated in coconut milk • Growth promoters • Produced in seeds, fruits, and roots • Effects: o Promotes mitosis and cytokinesis o Promotes development of buds o Inhibits leave senescence (loss & break down of chlorophyll) 3. Will be continued in next week’s notes!
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