Transcript 2-3 Sexual Rep`n in Plants

2.3 SEXUAL
REPRODUCTION IN PLANTS
Recall: Many plants can reproduce
asexually.
 Plants also reproduce sexually.
 The products of sexual reproduction in
plants are seeds
 A seed contains:



an embryo,
a food supply
and a seed coat to keep the embryo moist.
Plant Types
 Robert
Brown classified seed bearing
plants into two types based on the seeds:

Angiosperms: flowering plants
• Over ½ of all known plant species

Gymnosperms: non-flowering plants
• Most produce seeds inside cones
Angiosperms
 These
plants have large
(chrysanthemums) or tiny (grass) flowers.
 Seeds form inside flowers.
 A pod or shell forms around the seeds.
 Flowers contain the plant’s reproductive
organs.
Angiosperms
 There
are males, females and
hermaphrodites.
 Females have pistils, males have
stamens.
 Gametes are produced and must join to
form a zygote.
 Zygotes grow into embryos.
The Stamen (Male)
Grains – the male gametes in a
hard shell.
 Anther – where pollen is made and
stored.
 Filament – the stalk supports the anther.
 Pollen
The Pistil (Female)
ovules – sacs containing the female gametes.
 ovary – swollen base of the pistil containing
ovules.
 Stigma – sticky “lip” of the top of the pistil
which catches pollen grains.
 Style – the stalk that holds up the stigma.

Flower Parts
Animation
-scroll down for two animations
Flower Dissection
Ovary Cross Section
Pollination in Angiosperms
 Wind
and insects carry pollen to the
stigma. Angiosperms often have
bright colors, and strong odours to
help insects find it.
http://www.britannica.com/eb/article-9110808/pollination
Pollen: Shape, Color & Size
pollen Tube
 Click

on pollen and Life Cycles
Watch second half of video
Pollination – Move
-clip on pollen tube growth
Angiosperms
Self Pollination – pollen from the same
plant lands on the stigma.
Cross Pollination – pollen from different
plants of the same species land on the
stigma.
Fertilization in Angiosperms
When a pollen grain lands on the stigma:
- a pollen tube begins to grow through the style
down to the ovary and into one ovule.
- a sperm is released from the pollen grain
which swims down the pollen tube.
- the sperm and egg unite forming a zygote.
Seed Development in
Angiosperms
- As soon as the pollen lands on the stigma the
female’s ovule begins to form into a seed.
- The food for the growing embryo is called the
cotyledon. The sac around the ovule forms the
seed coat.
- the embryo forms a leaf, a stem, and a root.
- the ovary begins to mature turning into a fruit.
Lily Meiosis





HowStuffWorks Videos "Plant Biology: Making Pollen“
HowStuffWorks Videos "Plant Biology: Making Eggs"
HowStuffWorks Videos "Plant Biology: Pollination and
Fertilization“
HowStuffWorks Videos "Plant Biology: Germination
and Growth"
http://samson.kean.edu/~breid/flower_lab/angi_lab.ht
ml#LILY
• Excellent pictures
Gymnosperms
- seeds form inside cones.
- Cones open to let out the tiny seeds
- The seed coat protects the seed from
drying out.
- Some plants reproduce sexually without
bearing seeds. Examples include ferns
and mosses.
Seed Dispersal in Angiosperms
 Fruit
aids in dispersal of seeds.
 All About Seeds
 Name and briefly describe 4 methods of
seed dispersal from page 67.
 Why
is seed dispersal important?
Flower Dissection
Objectives
 To identify the major parts of a plant and
flower and describe the function of each
part.
 To thoughtfully, safely and respectfully
complete an anatomical dissection.
Materials
 Lily
bloom
 Paper plates/plastic tray
 Scissors or razor blade (to open the ovary)
 Hand lens
 Tweezers
 Dissecting scope (One for the class)
Procedure

Tomato Plant
Investigation
Tomato Seedling
Growth Chart
Graphing Procedure
1.
Title – put a descriptive title at the top of the
page

2.
Variables


3.
Tomato Plant Growth
Independent variable on x-axis – Time (days)
Dependent variable on y-axis – Plant Height (cm)
Range (subtract smallest # from largest #)


X-axis – 35 days
Y-axix – 15 cm or 30 cm
Graphing Procedure
4.
Labelling


5.
Label the independent variable on the X-axis
Label the dependent variable on the Y-axis
Increments

Mark the increments
•
•
6.
Each line is one day, mark every fifth day
Every second line is one cm
Plotting Data


Represent each entry with a dot
Join the dots with a line