chapter 24 outline
chapter 24 outline BIOL 1110
Popular in Introduction to Botany
Popular in Biology
This 4 page Class Notes was uploaded by Caitrín Hall on Tuesday January 26, 2016. The Class Notes belongs to BIOL 1110 at University of Connecticut taught by Bernard Goffinet in Summer 2015. Since its upload, it has received 12 views. For similar materials see Introduction to Botany in Biology at University of Connecticut.
Reviews for chapter 24 outline
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 01/26/16
Angiosperm Diversity and Reproduction 24.1 Flowering plants are enormously diverse, but share a suite of defining features Defining characteristics Flowering plants – vascular seed plants that reproduce by forming flowers (reproductive shoots bearing one or more leaflike organs Double fertilization – one sperm is delivered to egg through pollen tube to fertilize egg and produce zygote; second sperm combines with different female gametophyte cells to produce a nutritive tissue (endosperm) **only a trait of angiosperms** Ovules – produced within carpels, which ripens into a fruit containing seeds; contained in “enclosing vessels” Contain vessels in xylem Gymnosperms and angiosperms Arose from common ancestor that underwent wholegenome duplication – allows greater gene diversification Presence of ovules and seeds Angiosperms Monocots o One cotyledon o More endosperm in mature seeds o Long, narrow leaves with parallel venation o Stem vascular bundles scattered o Flower parts in multiples of 3 o Pollen grains have one pore Eudicots o Two cotyledons o Embryos use more of endosperm as they mature o Broad leaves with netted venation o Stem vascular bundles arranged in ring o Flower parts in multiples of 4 or 5 o Pollen grains have 3 surface pores Cotyledons – embryonic leaves that store organic food 24.2 The structure and diversity of flowers Pistil – coherent group of ovulebearing carpels; surrounded by microsporangiabearing stamens surrounded by petals sounded by sepals Sepals protect the flower bud Evolution of sepals and petals from sporophylls o Vegetative shoot meristem floral meristem o Brought about by environmental cues—day length, internal chemical signals o A, B, C, D, E gene classes encode transcription factors that alter gene expression Sepals: A, E Petals: A, B, C, D, E Stamens: B, C, E Carpels: C, E D determines development of ovules o Mutating one gene changes organ’s identity in different whorl changes Peduncle – stalk that bears single flower or an inflorescence – cluster of flowers o Variation in inflorescences reflects adaptation to different means of pollination Receptacle – enlarged area where flower parts are attached Perianth = sepals + petals Tepals – flowers whose petals and sepals are similar in shape and color Early stamen are shaped like leaves (sporophylls characteristic) Modern stamen – long, thin filament terminated by an anther, which contains pollen sacs with sporopollenin to protect male gametophytes Modern carpel – round lower ovary that protects ovules, style through which pollen tubes grow, terminal stigma where pollen grains adhere Complete flowers posses all types of floral whorls; incomplete lack one or more parts Perfect flowers have stamens and carpels; bisexual Imperfect flowers lack either stamens or carpels; unisexual Monoecious plants have staminate and carpellate flowers; crosspollination Dioecious plants have male and female parts on separate plants; selfpollination Superior – sepals, petals, and stamens are attached to receptacle below ovary Inferior – sepals, petals, and stamens are attached above ovary; more ovule protection Regular = radial symmetry Irregular = bilateral symmetry; more likely to attract biotic pollinators 24.3 The angiosperm sexual life cycle involves an alternation of generations Flowering plant = diploid sporophyte stage; produces spores by meiosis Spores haploid gametophytes haploid gametes by mitosis Heterosporous – 2 types of spores (megaspores and microspores) o Gametophytes are Endosporic—develop within mega/microspore wall Sexual life cycle begins when seed germinates o Embryonic sporophyte grows into adult by mitotic division o Mature sporophytes produce flowers under right conditions o Pollen sacs produce microsporocytes that undergo meiosis to produce 4 haploid microspores divide by mitosis to form 2 cells within each microspore wall—large tube cell and small generative cell = microgametophyte stage = pollen grain = immature male gametophyte o Single diploid megasporocyte arises in each ovule divides by meiosis to form 4 haploid megaspores (1 survives) develops by mitosis into megagametophyte o Double fertilization produces a zygote and an endosperm Pollen tube enters ovule through micropyle One sperm fuses with egg cell—produces diploid zygote— while other enters central cell and fuses with its two nuclei —produces triploid (3N) endosperm nucleus Angiosperms store food only when chances of embryo development are high Apomixis – asexual reproduction; embryo is genetically identical to parent 24.4 Angiosperm embryos and seeds pass through stages of development Mature seed – nutritionally independent of parent Embryo ceases to grow Integuments of ovule form hardened seed coat Monocot – endosperm stores food and supplies energy for germination/establishment of seedling; cotyledon digests, absorbs, transfers food reserves in endosperm to embryo during germination Eudicot – endosperm food reserves are transferred into cotyledons and later used to aid seedling development 24.5 A fruit is a mature ovary containing seeds Derived from walls of ovary Fruit evolved as a mechanism for seed dispersal Fleshy or dry, single or in aggregates Chapter Wrap-up Examine and Discuss Self Test 1. What does the word “angiosperm” mean? How do angiosperms differ from gymnosperms, pteridophytes (ferns), and bryophytes (liverworts, mosses, hornworts)? 2. Distinguish monocots from dicots by describing leaf, stem, root, flower, pollen, and seed embryo features typical of each. 3. Distinguish the following pairs or trios of terms, all of which are concerned with flower structure: a. peduncles and pedicels b. petals, sepals, and tepals c. calyx and corollad. stamens and carpels e. filaments and anthers f. ovary, style, and stigma 4. Distinguish between the following contrasting terms used to describe flowers or flowering plants, based on features of the floral parts: a. complete versus incompleteb. perfect versus imperfectc. staminate versus carpellate (or pistillate) d. monoecious versus dioecious e. superior versus inferior ovary f. regular (radially symmetrical) versus irregular (bilaterally symmetrical) flowers. 5. Define the terms “simple fruit,” “accessory fruit,” “aggregate fruit,” and “multiple fruit.” Give an example of each. 6. Describe some of the environmental conditions that influence seed germination. Applying Concepts 1. Imagine that you are in the produce section of your local grocery or health food store. What botanical categories of fruits are you most likely to find there? 2. In many flowers, pollen is produced either well before or considerably after carpels produce female gametophytes. What is the advantage to the plant of this timing difference? 3. Are all imperfect flowers also incomplete? Are all incomplete flowers also imperfect? Explain your reasoning. 4. Tomatoes are commonly referred to as vegetables. Does this make sense botanically? 5. Construct a simple dichotomous key to the following fruit types: berries, drupes, pomes, follicles, legumes, capsules, achenes, samaras, grains, and true nuts.
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'