Download Plant Reproduction

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Flowers
Seeds
Pollination
Germination
*In order for plants to be
successful in many different
environments they must be able
to reproduce themselves.
*The reproductive patterns of
plants reflect the reproductive
patterns of any other organism.
*
*Male must meet female in
some way.
*Male reproductive cells are
smaller, numerous and
motile (able to move).
*Female reproductive cells
are large, single and sessile
(not able to move)
*A plant will spend most of it’s time
and energy on making sure that the
ovuole is taken care of as there is
only one per flower.
*Some flowers are only female, some
flowers are only male and some
flowers have both male and female
gametes (pollen and ovuole).
*These flowers are considered
hermaphroditic (can fertilize
themselves).
*A flower is a specialized shoot with four circles
of modified leaves: sepals, petals, stamens, and
carpals.
Fig. 30.13a
*The sepals at the base of the flower are
modified leaves that enclose the flower
before it opens.
*The petals lie inside the ring of sepals.
*These are often brightly colored in plant
species that are pollinated by animals.
*They typically lack bright coloration in
wind-pollinated plant species.
*Neither the sepals nor petals are directly
involved in reproduction.
* Stamens, the male reproductive organs, produce
microspores (pollen) that will give rise to gametophytes
(new plants).
*A stamen consists of a stalk (the filament) and a
terminal sac (the anther) where pollen is produced.
*Carpals are female reproductive organs that produce
megaspores (ovuole) and their products, female
gametophytes.
*At the tip of the carpal is a sticky stigma that receives
pollen.
*A style leads to the ovary at the base of the carpal.
*Ovules and, later, seeds are protected within the
ovary.
* Fruits are produced by the ovary developing.
The fruit will protect the seeds and aid in
dispersal. Fruits in angiosperms include
vegetables and fruits.
* Plants use pollination as a way to reproduce.
* As the pollen matures, the anther bursts open
releasing all the pollen.
* This is carried to the stigma of the same or
other flowers.
* Process is called pollination
* Definition: transfer of pollen from anther to
stigma
*
*There are 2 types of pollination:
*1) Self Pollination – is when the pollen of
one flower falls on the stigma of the
same flower or another flower of the
same plant.
*2) Cross Pollination – is the transfer of
pollen from the stigma or one flower to
the anther of a flower of another plant
of the same species.
*Cross Pollination can be by wind or
animals but mostly insects.
*
*During fertilization, the pollen
nucleus fuses with the female
nucleus to produce the zygote.
*The zygote grows into the seed.
*The ovary grows into the fruit –
different adaptations for seed
dispersal.
*Fruit forms from concentration of
nutrients
*
*Fruits can be dry – roses,
dandelions or peas.
*Fruits can be juicy – apples,
cherries or plums.
*
*
*Seed and Fruit Dispersal results in the
spreading of fruits and seeds to other
environments and ecosystems.
*Important because:
*1) The seeds will not overcrowd in an
area and this minimizes competition for
resources.
*2) It spreads the seeds to other
environments which might offer better
chances of survival for these plants.
*
Fruits – Seed dispersal - Wind
Fruits – Seed dispersal - Water
Fruits – Seed dispersal - Animals
*
Internal/External Structure, Metabolic events
and Needs for Germination – Why do we have
seeds?
*Plumule: develops into the stem.
*Cotelydon: stores or absorbs food for the
developing embryo.
*Radicle: first part of a seedling (a growing
plant embryo) to emerge from the seed
during the process of germination – primitive
root
*Micropyle: small pore on the seed coat for
absorption of water.
*Testa: outer seed coat, protective layer
*
*
*1) Water is needed to:
*Activate hormones and enzymes
*Swelling of the seeds = bursting of seed
coat.
*Transport of simple materials to the
embryo – to be used for respiration and
growth.
*Metabolic and enzyme actions – occur in
solution, therefore need water.
*Conversion of storage compounds into
simple components (i.e. starch to
glucose)
*
*2) Oxygen is needed for
aerobic respiration.
*Without a supply of oxygen,
seeds fail to germinate
because of the lack of
energy – in the form of ATP.
*
*3) Suitable temperature
*All reactions (in germination) are
controlled by enzymes.
*Optimal temperature for enzyme
activity leads to faster rate of
germination.
*Freezing = inactivates enzymes
*Very high temperatures = denatures
enzymes
*
*1) Water enters the seed through a
hole in the seed coat – microplye.
*2) Water moves into the tissues and
cells by osmosis.
*3) The seed swells and the seed coat
bursts.
*4) Water activates gibberelline, the
hormone needed for breaking the
dormancy of the seed.
*
*5) Gibberelline activates amylase which
catalyzes the break down of starch to
maltose to glucose.
*6) Glucose is mobilized (transported) to
the embryo.
*7) Embryo absorbs glucose and uses it
for respiration (oxygen needed).
*8) Cell division, growth and elongation
occurs in the embryo = radicle to root,
plumule to stem.
*
*9) Nutrients needed for growth all
supplied by food stored in cotelydons.
*10) As nutrients are consumed, first
leaves start to appear = photosynthesis.
*11) When photosynthesis starts,
seedling absorbs water and minerals
from the soil, Co2 from the atmosphere
and sunlight.
*
*
Starch, Proteins and Lipids
* Plants make glucose in the process of photosynthesis.
* Glucose is used for respiration to produce energy which
powers different processes in the plant such as active
transport.
* Excess glucose can be converted to storage materials.
*
*There are 3 main types of storage
materials:
*1) Starch
*2) Proteins
*3) Lipids *
*Examples include:
* Corn seeds
* Potato tubers
* Rice and wheat grains
*
*Examples include:
* Seeds of leguminous
plants:
* Peas
* Beans
* Lentils
*
*Examples include:
* Olive fruits and seeds
* Sunflower seeds
*