* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download NOTES: Plant Reproduction and Development
Survey
Document related concepts
History of botany wikipedia , lookup
Plant breeding wikipedia , lookup
Plant physiology wikipedia , lookup
Plant ecology wikipedia , lookup
Evolutionary history of plants wikipedia , lookup
Ornamental bulbous plant wikipedia , lookup
Gartons Agricultural Plant Breeders wikipedia , lookup
Ecology of Banksia wikipedia , lookup
Plant morphology wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
Pollination wikipedia , lookup
Fertilisation wikipedia , lookup
Plant reproduction wikipedia , lookup
Transcript
NOTES: CH 38 - Plant Reproduction *Modifications in reproduction were key adaptations enabling plants to spread into a variety of . * Water has been replaced by and as a means for spreading gametes. * Embryos are protected in SEEDS. * Vegetative (asexual) reproduction for propagation of some plants in a variety of environments. Our focus in this chapter will be…SEXUAL REPRODUCTION GAMETOPHPYTES: reproductive structure of plants -. (sperm and egg cells) -gametes fuse to form a (2n) that develops into a multicellular plant …ALTERNATION OF GENERATIONS! FLOWERS: -the reproductive structure of angiosperm sporophytes -four sets of modified leaves: 1) 2) 3) : -anther, filament 4) : stigma, style, ovary STAMENS and CARPELS (PISTILS) are the reproductive parts of the flower. Female gametes develop in , which contain the this occurs at the base of the carpel /pistil, inside the Male gametes develop in the stamen inside this occurs at the stamen tips within chambers of the FLOWER VARIATIONS: Complete flower = flower with Incomplete flower = flower missing one or more of these parts (e.g. most grasses do not have petals on their flowers) Perfect flower = flower having both (a.k.a. bisexual) Imperfect flower = flower that is either (a.k.a. unisexual) Monoecious = “one house”; plants with both staminate and carpellate flowers on the same plant (ex: ) Dioecious = “two houses”; plants having staminate and carpellate flowers on separate plants (ex: ) Development of the Male Gametophyte (POLLEN): POLLEN GRAIN = the immature male gametophyte; develops within the anthers of stamens in an angiosperm extremely durable; tough coat to prevent biodegradation at the time of pollination: A pollen gain consists of 2 cells (both haploid): -GENERATIVE CELL: -TUBE CELL: ; contains the generative cell Development of the Female Gametophyte (EMBRYO SAC) ● Female gametes are contained in the EMBRYO SAC (diagram of embryo sac below): Embryo Sac: egg cell (OVUM) at one end ovum flanked by 2 syngerids (help to attract sperm cells) two nuclei in center (“polar nuclei”) POLLINATION: -occurs when wind- or animal-born pollen released from the anthers lands on the STIGMA at the tip of the carpel POLLINATION = Methods of Pollination / spread of pollen: • • • (most plants cross-pollinate) To prevent self-pollination (and thus ensuring sperm and egg from different plants meet), some plants: -have stamens and carpels that ; -have structural arrangement of flower parts that reduces the chance of pollen getting transferred from stamen to carpel; -are SELF-INCOMPATIBLE (a biochemical block that prevents the pollen grain from developing and fertilizing the egg) SELF-INCOMPATIBILITY: from the same, or closely related, plant by the stigma after POLLINATION… -pollination is followed by this sequence: 1) a pollen tube grows from the pollen grain, down the carpel, into the embryo sac; 2) sperm are discharged resulting in fertilization of the eggs; 3) the zygote develops into an embryo; 4) as the embryo grows, the ovule surrounding it develops into a 5) while seed formation is taking place, the entire ovary is developing into a more seeds. ; , which will contain one or DOUBLE FERTILIZATION: When a compatible pollen grain lands on a stigma of an angiosperm, double fertilization occurs. DOUBLE FERTILIZATION = with two cells of the embryo sac Steps: 1) pollen grain adheres to stigma, germinates, and extends a pollen tube toward the ovary; 2) generative cell divides (mitosis) to form 2 sperm; 3) directed by a chemical attractant, pollen tube enters and discharges its 2 sperm nuclei into the embryo sac; 4) 1 sperm unites with the egg ; 5) other sperm combines with the 2 polar nuclei to form a 3n (triploid) nucleus in the large central cell of the embryo sac. this central cell will give rise to the (a food storing tissue for the seed/embryo) **after double fertilization, each ovule develops into a seed and the ovary into a fruit surrounding the seed(s). ENDOSPERM: • (which it provides to the developing embryo) Structure of the mature seed: in mature seeds, the embryo is quiescent (dormant) until germination • the seed dehydrates until its water content is only 5-15% by weight. • the embryo is surrounded by endosperm, enlarged cotyledons, or both. • the seed coat is formed from the outer layers / integuments of the ovule. Dicot seed structures: (diagram of mature dicot seed): -cotyledons = -hypocotyl = embryonic axis -radicle = -epicotyl = embryonic axis *Seeds are dispersed from the source plant when fruits are moved about by the wind or animals. *Seeds deposited in soil of the proper conditions (moisture, nutrients), will GERMINATE. FRUITS: -ovary develops into fruit (adapted for ) *Fruits ripen about the time seeds are becoming fully developed Ripening fruits are characterized by: 1) fruit becomes softer as a result of enzymes digesting the cell wall components; 2) colors usually change and as organic acids or starch are converted to sugar; 3) these changes produce an edible fruit which entices animals to feed, thus !