Plants

the lives of plants depend on … to carry out photosynthesis

sunlight, gas exchange, water, and minerals

photosynthetic prokaryotes effect on the evolution of plants

added oxygen to the atmosphere and provided food for consumers

demands of life on land favoured the evolution of plants that were able to

draw water from soil, resist drying out, reproduce without water

land plants effect on other life on earth

new ecosystems emerged and organic matter began to form from soil

all plants

1. are eukaryotic

2. have cell walls containing cellulose

3. carry out photosynthesis using chlorophyl a and b

4 features that divide plants into 5 major groups

1. embryo formation

2. specialised water-conduction tissues

3. seeds

4. flowers

scientists classify plants into finer groups within the major branches by

comparing DNA sequences of various species

life cycle of plants’ 2 alternating phases

diploid (2N) and haploid (N) phases

alternation of generations

shift between haploid and diploid phases

sporophyte

multicellular diploid (2N) phase (AKA spore-producing plant)

gametophyte

multicellular halpoid (N) phase (AKA gamete-producing plant)

sporophyte produces haploid spores through

meiosis

spores grow into multicellular structures called

gametophytes

gametophytes produce

reproductive cells called gametes (sperm/egg)

during fertilisation, sperm and egg fuse producing

diploid zygote

diploid zygote develops into

a sporophyte

evolution caused a reduction in size of _______ and increasing size of _____

gametophyte; sporophyte

green algae can absorb moisture and nutrients directly from their surrounding because

they are single cells/branching filaments (so no specialised tissues)

how do chlamydomonas reproduce

asexually by mitosis but if environmental conditions become unfavorable they switch to sexual reproduction by meiosis

rhizoids

thin filaments on moss

how does moss resist drying

it has a waxy coating

bryophytes

have specialised reproductive organs and grow from embryos, generally small and found only in damp soil since they lack vascular tissue

vascular tissue

water conducting tissue, makes it possible for plants to draw water up against the pull of gravity

plants without vascular tissue

have a height limited to a few centimeters

archegonia

egg-producing reproductive organ in bryophytes

dominant stage in bryophyte life cycle

gametophyte

antheridia

sperm producing reproductive organ in bryophytes, need standing water to swim to egg cells

sporangium

spore capsule that caps growth of zygote into a sporophyte

tracheophytes

vascular plants

tracheid

specialised type of water conducting hollow tube like cell with cell walls thickened by lignin

xylem

tissue that carries water upward from roots to every part of plant (tracheids found here)

phloem

second transport tissue that transports nutrients and carbohydrates produced by photosynthesis, long cells specialised to move fluids throughout the plant body

__________ make it possible for vascular plants to move fluids through the bodies against the force of gravity

xylem and phloem

fern sporophytes produce spores that grow into

thin heart-shaped haploid gametes that live independently of the sporophyte

seed

plant embryo, food supply encased in protective covering

living plant within seed

is diploid and represents an early stage of sporophyte phase of the plant life cylce

gametes of seed plants ____ need standing water for fertilisation

don’t

adaptions that allow seed plants to reproduce without standing water

reproductive processes that take place in cones or flowers, transfer of sperm by pollination, protection of embryos in seeds

in seed plants, where do the gametophytes grow and mature ?

within the sporophyte

gymnosperms

bear their seeds directly on the scales of cones

angiosperms

flowering plants, bear the seeds in flowers inside a special layer of tissue that surrounds and protects the seed, include nearly all crops grown for food

entire male gametophyte of seed plant is contained in

pollen grain

pollination

transfer of pollen from male reproductive structure to female reproductive structure by wind or insects

_____ surrounds and protects the embryo, preventing it from drying out

the tough seed coating

two types of cones that conifers produce

pollen cones and seed cones

in pollen cones, ______ contains the entire male gametophyte stage

pollen grain

near the base of each scale of seed cones are

two ovules

pollen tube

grown when grain splits open if pollen lands near ovule

ovaries

surround and protect the seeds

fruit

structure containing one or more matured ovaries

cotyledon

seed leaves

flowering plants with one seed leaf

monocot

flowering plants with two seed leaves

dicots

scientists categorise angiosperms by what characteristics

1. number of leaves

2. strength/composition of stems

3. number of growing seasons they live

monocots vs dicots

monocots

-single cotyledon

-parallel veins

-petals in multiples of 3

-vascular bundles scattered

-fibrous roots

dicots

-two cotyledon

-branched veins

-petals in multiples of 4 or 5

-vascular in ring arrangement

-taproot

woody plants

made primarily of cells with thick cell walls that support the plant body

herbaceous plants

do not produce true wood and have unwoody stems

annual

pass through entire life cycle in one growing season

biennials

live for two growing seasons; seeds and flowers form in the second season

perennials

regrow year after year

why are flowers an evolutionary advantage?

attract animals that can pollinate which is more efficient than wind pollination (in gymnosperms)

flower specialized leaves

sepals, stamens, petals, and carpels

sepal

modified leaves in outermost part of flower, encloses bud before it opens, protects the flower as it develops

stamens

male reproductive part of flower, consists of filaments and anthers

anthers

structures that produce pollen grains

carpels

female reproductive part that forms seeds in the innermost floral part, forms ovaries

embryo sac

female gametophyte from seven cells formed in mitosis

double fertilization

when 2 distinct fertilizations take place: zygote production and endosperm production within seed

benefits of double fertilization

spends very little energy so plant can spend saved energy on making more seeds

vegetative reproduction

asexual reproduction in many flowering plants, produces many identical copies quickly by mitosis

benefits of vegetative reproduction

quick, identical offspring which enables well-adapted individuals to rapidly fill favorable environment, does not require gametes, flowers, or fertilizatio

purpose of endosperm

nourish seedling

seed dispersal

1. animal- through droppings, fruit meant to attract animals so they eat fruit but seed doesn’t get digested so it is dispersed (ie birds)

2. wind- wind carries seeds (ie. dandelion)

3. water-floating fruit is transported to new places (ie. coconuts)

dormancy

state in which embryo is alive but not growing

germination

when growth of embryo resumes and seed sprouts into plant