Bio II Notes 2/16
Bio II Notes 2/16 BIO 1144
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This 4 page Study Guide was uploaded by Rocket on Friday February 19, 2016. The Study Guide belongs to BIO 1144 at Mississippi State University taught by Thomas Holder in Spring 2016. Since its upload, it has received 28 views.
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Date Created: 02/19/16
“Ideal Flower” 4 sets of highly modified leaves in whorls at tip of modified stem Highly modified, Shortterm, Shoot system Diagram +Calyx and Corolla re “sterile” modified leaves, not directly involved in sexual reproduction Calyx: Protection of unopened bud Corolla: attract pollinators, contain aroma +Androecium + Gynoecium are “fertile” modified leaves, directly involved in sexual reproduction Androecium (all stamens): “male household” male portion of flower, production of pollen (sperm) Gynoecium (all pistils): “female household” eggs are produced, female gametes +Sporophyte Generation (2N) Pedicel, Receptacle, 4 sets of modified leaves are 2n 4 sets of modified leaves arise from the receptacle +Gametophyte Generation (1N) Pollen (sperm) Egg Sexual Cycle ➔ Male side: Pollen formation within formation of stamen Anther: bilobed structure with 2 pollen chambers per lobe +Pollen diagram +Each 2N microscopic mother cell produces four 2celled pollen grain Pollination Pollen produced within Anther of Stamen(s) Transfer of pollen from an Anther to a Stigma +Self Pollination: Transfer within same flower/same plant Low genetic Diversity +Cross Pollination Transfer of pollen between plants +Pollinating Agents Wind: tiny lightweight pollen, requires zero energy from plant, not very accurate Water: only truly aquatic plants use this, pollen can float, very inaccurate Animals: majority of plants use animals, plants are tricking animals with reward, nectar found in base of flower attracts animals who consumes it and at the same time pollen gets all over animal, animal moves around and spreads pollen, petals and aroma attract pollinators Sexual Cycle ❖ Female Side +Ovule = future seed Enclosed within ovary of pistil (carpel) 1 to many per ovary +Ovule attached to central axis of hollow ovary or to the ovary wall Ovules are always “enclosed” +Within ovule there is a single large 2N cell Called Megaspore Mother Cell (diploid structure ) *Embryo Sac is within Nucleus and Integuments inside ovary of pistil Syngamy: 1n egg + 1n sperm = 2n Zygote(single cell)(fertilized egg) +Pollen “germinates” Tube cell produces pollen tube Generative cell (1n) divides by mitosis/cytokinesis to produce two 1N sperm Pollen tube enters micropyle, digests nucellus *Tip of pollen tube diagram Pollen tube enters one synergid , releases its contents, synergid ruptures, tube nucleus degrades, 2 sperm released into the large central cell Micropyle closes (seals up) pollen is trapped Double Fertilization 1n egg + 1n sperm = 2n Zygote(single cell)(fertilized egg) 1n sperm + 2 (2N) central nuclei (polars)+ 3N (1 degree) Primary endosperm cell Post Fertilization: (within ovule) 2n zygote → mitosis +cyto = Multicellular 2n embryo 3n primary → mitosis + cell = multicellular 3n endosperm (nutritive tissue for embryo) endosperm cell Ovule with 2n zygote matures into seeds within 2n embryo Ovary of pistil matures, enlarges with sugar and water into a fruit with enclosed seeds (= ovules) (fruit defined with nature ovary with ovules) Seed Dispersal (enclosed in fruit) Mechanism + Wind: windblown fruits, goes a distance but not that far, has to be lightweight + Water: seeds able to float, minimum effective + Animals: Majority! trick/reward respond, animal consumes fruit, passes through animals, seeds disperse with feces Seed Germination Seed with 2n embryo → period of Dormancy → Broken by combo of environmental and internal factors *temp, soil moisture, hormones Radicle 1st root emerges goes downwards, shoot emerges after going upward *END OF MATERIAL FOR EXAM NUMBER 2
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