bio 1050 flashcards - plants

nomenclature of hybrids

new genus is a combined name of two genera, X is used to indicate the cross

three domains of life

eukarya, bacteria, archaea

endosymbiont theory

theory that proposes that mitochondria and chloroplasts were once individual prokaryotic organisms that eventually integrated to become one eukaryotic cell

evidence of endosymbiont theory

inner membranes similar to plasma membranes of prokaryotes, organelles create their own DNA, division and DNA structure are similar in organelles and prokaryotes, their ribosomes are more similar to prokaryotic

angiosperms appeared about..

360 million years ago

origin of plants

470 mya

chlorophytes

division of green algae
contain chloroplasts, cell walls, and use starch as storage for photosynthates

ancestor of land plants

green algae

first plants to grow on land

non-vascular plants (ex. moss, liverworts) around 475 mya

move to land involved

creation of soils, development of a cuticle

bryophytes

reproduce by spores, requiring water
have rudimentary leaves, roots, or stems
grow in moist, shady areas

sporophyte generation (diploid 2n)

produce haploid spores via meiosis
spores grow into gametophytes

gametophyte generation (haploid n)

produce haploid gametes by mitosis
fusion of gametes (fertilization) produces diploid sporophyte

mitosis

begins with one haploid or diploid cell, produces two identical daughter cells (two haploid or diploid)

meiosis

first meiotic division produces two haploid, second produces four haploid

seedless vascular plants

first vascular plants, appeared around 425 mya

vascular system

xylem and phloem carry nutrients around plant
allowed plants to grow tall

xylem

carries water up from roots and transports

phloem

carries sugars made via photosynthesis in leaves and transports

angiosperms

flowering plants producing seeds within protective fruit/ovary

monocots

single cotyledon, parallel veined leaves

eudicots

4 or 5 merous flowers, branching-veined

“lower plants”

mosses, ferns

“higher plants”

angiosperms, gymnosperms

reproductive shoot of angiosperms

flower

carpel

consists of ovary at the base and style leading up to a stigma where pollen is recieved

flower consists of…

speals, petals, stamens, carpels

stamen

consists of stalk, with anther where pollen is produced

methods of pollen attraction in flowers

colour, nectar, odor, mimicry/deception

pollinator reward

pollen and nectar

pollen

produced by male parts of seed plants for reproduction, eaten by animals (contains nutrients)

nectar

sugar-rich liquid produced by plants, is relied on by pollinators (ex. butterflies) for all their nutrition for several months

plant trickery - mimicry

flowers can mimic insect shapes, inducing a response from insects (ex. reproduction, fight), and results in the uptake of pollen and transferration

examples of pollinators

bees, butterflies, bats, birds

characteristics of plants pollinated by bats

open at night, dull colours, positioned below foliage, exude musty odor, large and tough with lots of pollen/nectar

characteristics of plants pollinated by birds

red/orange in colour, deep tubes without landing platform, often horizontal, have lots of nectar but emit no odor

co-evolution

plants and the animals that pollinate them evolved at the same time and in ways that benefit the other

wind-pollinated flowers

small, colourless, odorless, no nectar, no petals (or very small petals), dangle and wave in the open, produce more pollen grains per ovule compared to animal-pollinated

wind-carried pollen grains

small, smooth, and dry, 20-60 micrometers in diameter, shape is frisbee-like

angiosperm life cycle

sporophyte-dominant, heterosporous - producing microspores and megaspores

microspores

generate pollen grains as the male gametophytes

megaspores

form an ovule that contains female gametophytes

anthers

pollen-producing part at top of a flower’s stamen (male component)
made up of four lobes called pollen sacs

pollen sacs

found within anthers, containing a mass of dividing cells called microsporocytes

microsporocytes

within pollen sacs in anthers
cells that divide via meiosis forming four haploid microspores

microspores

generated by microsporocytes in pollen sacs
each microspore divides via mitosis forming two-celled pollen grain. role is to produce sperm cells for ferilization

pollen tube

produced when germination of a pollen grain occurs, grows through stigma and style and enters ovary

double fertilization

two sperm cells created by the generative cell pass through a synergid cell - one fuses with egg the the other with central cell. fusion of sperm and egg cell forms a diploid zygote which grows into an embryo, while fusion of sperm nucleus with polar nuclei forms triploid nucleus, which divides to become a reserve tissue called the endosperm

types of angiosperms

complete/perfect, incomplete/imperfect, inflorscence

complete/perfect angiosperms

contain all 4 floral organs/whorls (ex. apple)

incomplete/imperfect angiosperms

lack one or more floral organs/whorls such as stamens or carpels

inflorescence angiosperms

clusters of flowers (ex. wild carrot)

monoecious plants

male and female flowers are separate, but carried on the same plant. developmental timings are asynchronous

self-pollination or selfing

transfer of pollen from anther to stigma in the same flower, and transfer of pollen from one flower to another on the same plant

cross-pollination or outcrossing

involves transfer of pollen from one genetically distinct plant to the stigma of another (increases genetic diversity)

dioecious plants

plants have either male or female flowers

s-genes

recognition of self is based on this - genes for self-incompatibility
there can be many alleles of this

gemtophytic incompatibility

if a pollen grain has an allele that matches an allele of the stigma it lands on, the pollen tube fails to germinate or fails to grow through the style to the ovary

sporophytic incompatibility

the pollen phenotype is determined by the diploid genotype of the plant on which it was produced because proteins corresponding to both alleles of the pollen parent are deposited into the pollen coat

self-fertilization advantages

widespread propagation of the same adapted genotype
no need for wind or pollinators
little metabolic cost (little wasted pollen, no cost to produce nectar)

self-fertilization disadvantages

restricted opportunity to create new genetic combinations
inbreeding depression
loss of vigour

fruit

enlarged ovary that contains seeds

seed

embryo and nutrient source surrounded by a protective coat

flower

reproductive structure that produced gametes, protects and nourishes megaspore gamete, captures male gametes, nourishes embryos, develops seeds/fruits

simple fruit

fleshy or dry, dry can either be dehiscent or indehiscent
develops from a single carpel or several fused carpels of one flower

aggregate fruit

develops from many separate carpels of one flower

accessory fruit

develops from tissues other than ovary (ex. strawberry)

pathenocarpic

fruits that develop without fertilization, seedless (ex. grapes, banana, pineapple)

stimulative parthenocarpy

pollination or other stimulation is required for parthenocarpy

vegetative parthenocarpy

exhibited by plants that dont require pollination or other stimulation to produce parthenocarpic fruit

fruit and seed dispersal

plants life depends on finding fertile ground
to prosper seeds must be widely dispersed
use of biotic or abiotic dispersal agents

evolution modifications for wind dispersal

winged/plumed fruits
ballistic dispersal by violent dehiscence of pericarp

evolution modifications for water dispersal

buoyancy in seeds, surviving for months/years at sea
water pushes seeds against rocks, scraping the coat to remove dormancy

mechanical dormancy

scarification allows seeds to become active (stopping dormancy)

fruit as dispersal aids

stored food in fruit is not utilized by dormant seeds
animal vectors are used - many seeds in fruits can survive passage through animal digestive tracts

dispersal by animals

seeds get caught in fur, passed through digestive tracts, hoarding animals move seeds/fruits underground

seed dormancy

increases chances that germination will occur at a time and place most advantageous to the seedling
environmental cues are often required to break dormancy

physical dormancy

impermeable seed coat, mechanical dormancy
broken by passage through digestive tracts, mechanical nicking, stratification

components of dicot

radicle in centre, surrounded by two cotyledons
radicle has an epicotyl on the top and hypocotyl below
seed coat surrounding seed

components of monocot

one cotyledon (called scutellum)
rudimentary shoot is sheathed in coleoptile, coleorhiza covers young root
pericarp is fused with the seed coat - inside is the endosperm, radicle with epicotyl and hypocotyl, scutellum, coleoptile, and coleorhiza

seed germination

first step of growth of the embryo
after imbibition, enzymes activated and rapidly released to digest stored food into smaller molecules - which are transported and converted into energy needed for growth

germination - what it looks like

appearence of a radicle and shoot from the seed

emergence - what it looks like

appearance of a seedling shoot above the soil surface

epigeal

cotyledons emerge above the ground

hypogeal

cotyledons remain in the soil