CSU - BC 103 - Life 103 Week 7 - Class Notes

Created by: Caroline Hurlbut Elite Notetaker

Schools > Colorado State University > Biology > BC 103 > CSU - BC 103 - Life 103 Week 7 - Class Notes

This preview shows pages 1 - 2 of a 4 page document. to view the rest of the content

Angiosperm Reproduction & Biotechnology • key features of angiosperm life cycle —flowers
—fruits
—double fertilization • flowers have 4 floral organs that are modified leaves —carpels
—stamens
—petals
—sepals • stamen - male reproductive structure that consists of a filament stalk with a sac
called an anther where pollen is produced • carpel - female reproductive structure that consists of an ovary at the base and a
style leading up to a stigma where pollen is received • transfer of pollen can be done by water, wind, or animals (most commonly animals) • bees are the most important insect pollinators • double fertilization - 2 sperm deposited into embryo sac —one sperm fertilizes egg—>zygote
—other sperm combines with central cell (has 2 polar nuclei)—>triploid food- storing endosperm (3n) • endosperm is thin in monocots and thick in eudicots • a seed has 3 ploidys —integument (seed coat)=2n
—endosperm=3n
—embryo=2n • structure of mature seed —embryo, food supply, seed coat
—seed dehydrates as it matures and enters state of dormancy—>increases chance seed germinates at advantageous time/place —breaking of dormancy often requires specific environmental cues A. animal digestion
B. temp or light changes
C. fire
D. water —embryo consists of embryonic axis below cotyledons (hypocotyl, terminates in the radicle) attached to 2 fleshy cotyledons (seed leaves) • seed germination and development —germination depends on imbibition, the uptake of water by dry seeds
—radicle emerges first to anchor plant • sexual reproduction - increases genetic variation, evolutionarily advantageous but
only a fraction of seedlings survive • asexual reproduction - genetically identical organisms, no need for pollinator and can
be beneficial to successful plant in stable environment —fragmentation is common form of asexual reproduction

—in some species a parent plant’s root system gives rise to adventitious shoots that become separate shoot systems • some flowers self-fertilize to ensure every ovule will develop into a seed • dioecious species have staminate and carpellate flowers on separate plants • people modify crops by breeding and genetic engineering (artificial selection) —hybridization common in nature used by breeders to introduce new genes
—genetically modified plants may increase quality and quantity of food worldwide
—some plants have been modified to be resistant to insects and certain diseases
—golden rice is transgenic modified crop that puts vitamin A in rice
—most serious concern is introduced genes escaping into related weeds through hybridization—>superweeds

This is the end of the preview. Please to view the rest of the content