Transcript Plant Reproduction PPT

PLANT SEXUAL REPRODUCTION
WITH MEIOSIS
SEXUAL REPRODUCTION IN
SEED PRODUCING PLANTS
 Some plants sexually
reproduce through their
seeds.
 Before a seed can grow
into a new plant an egg
with ½ the amount of
chromosomes (female
gamete) must join with
pollen (male gamete) with
the other ½ of the
chromosomes to be
fertilized. (from meiosis)
2 TYPES OF PLANTS: GYMNOSPERMS
AND ANGIOSPERMS
 Gymnosperms
 Naked
seeds in cones
 No flowers
 Male cones = pollen (sperm
or male gamete)
 Female cones = egg inside ovule (female gamete)
 ½ of unpaired chromosomes from pollen join ½ of
unpaired chromosomes from egg to “fertilize” the
egg which now has all of its chromosomes paired.
 The transfer of pollen from a male reproductive
cone to a female reproductive cone is called
pollination.
ANGIOSPERMS
Pollination and fertilization take place in the
flower of the plant.
 The seeds are in a closed ovary unlike in
gymnosperms.

PARTS OF A FLOWER
Petals: attract insects
by their bright color
and scent.
 Sepals: Green leaves
around the outside of
the flower. Sepals are
usually smaller than
the petals. Used to
protect the flower
while it is still in bud.

FEMALE REPRODUCTIVE PARTS (PISTIL)
Stigma - sticky top part
at the top where pollen
lands
 Style - stalk that is in
between the stigma and
ovary
 Ovary - where the eggs
(female sex cell) are
formed
 Ovule – inside the ovary,
The egg will turn into
each one with its own
a fruit once fertilized.
seed

MALES REPRODUCTIVE PARTS (STAMEN)

Stamens: This is where pollen is made. It is the
male part of the flower.
 The
stamen has two parts:
 the
filament (a thin stalk)
 the anther which is where pollen (male sex cell) is made.
STRUCTURE OF THE FLOWERS (PG 277)
ANGIOSPERM REPRODUCTION

Sexual reproduction in a flowering plant has
FOUR main stages:
 Pollination
 Fertilization
 Seed
dispersal
 Germination
POLLINATION
A plant is pollinated when
the male gamete (pollen)
comes in contact with the
female gamete (egg).
 The pollen has to be carried from the stamen (male
reproductive organ) of one flower to the stigma (female
reproductive organ) of another.
 It is usually carried by bees, birds, or other small animals
but it can be carried by the wind.
 Flowers have nectar, scent, petals and other ways to
attract these organisms to move the pollen and help in
reproduction.

FERTILIZATION
When the pollen and the
egg join together to make
a seed.
 The part of the flower
surrounding the seed is
known as the fruit.
 The ovary (which forms the
fruit) swells up, sometimes
considerably. (Ex: an
apple)

SEED DISPERSAL – MOVING THE SEEDS AWAY
FROM THE PARENT PLANT SO THEY CAN GROW
A plant will disperse their seeds in many ways:
 1. Animals: by eating the seeds and excreting them (pooping)

2. Explosion: The fruit splits
open. Sometimes this happens
with a lot of force and the seeds
are shot out.

3. Animals Again: The fruits have
little hooks that stick to the fur of
animals.

4. Wind: The fruits have wings or hairs and this lets them get carried by
the wind. Ex: sycamore trees have winged fruits.

5. Water: The seeds are fall into moving water and are carried away.
GERMINATION

Germination is the process by which the seed
actually starts to grow.

Conditions needed for germination:
 warmth
 oxygen
 water

Without all three (water, oxygen and warmth)
the seed will not grow.